Quectel Wireless Solutions 201604M26 GSM/GPRS module User Manual

Quectel Wireless Solutions Company Limited GSM/GPRS module Users Manual

Users Manual

M26 Hardware Design GSM/GPRS Module Series Rev. M26_Hardware_Design_V1.1 Date: 2014-11-24 www.quectel.com
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 1 / 80 Our aim is to provide customers with timely and comprehensive service. For any assistance, please contact our company headquarters: Quectel Wireless Solutions Co., Ltd. Office 501, Building 13, No.99, Tianzhou Road, Shanghai, China, 200233 Tel: +86 21 5108 6236 Mail: info@quectel.com Or our local office, for more information, please visit: http://www.quectel.com/support/salesupport.aspx For technical support, to report documentation errors, please visit: http://www.quectel.com/support/techsupport.aspx GENERAL NOTES QUECTEL OFFERS THIS INFORMATION AS A SERVICE TO ITS CUSTOMERS. THE INFORMATION PROVIDED IS BASED UPON CUSTOMERS’ REQUIREMENTS. QUECTEL MAKES EVERY EFFORT TO ENSURE THE QUALITY OF THE INFORMATION IT MAKES AVAILABLE. QUECTEL DOES NOT MAKE ANY WARRANTY AS TO THE INFORMATION CONTAINED HEREIN, AND DOES NOT ACCEPT ANY LIABILITY FOR ANY INJURY, LOSS OR DAMAGE OF ANY KIND INCURRED BY USE OF OR RELIANCE UPON THE INFORMATION. ALL INFORMATION SUPPLIED HEREIN IS SUBJECT TO CHANGE WITHOUT PRIOR NOTICE. COPYRIGHT THIS INFORMATION CONTAINED HERE IS PROPRIETARY TECHNICAL INFORMATION OF QUECTEL CO., LTD. TRANSMITTABLE, REPRODUCTION, DISSEMINATION AND EDITING OF THIS DOCUMENT AS WELL AS UTILIZATION OF THIS CONTENTS ARE FORBIDDEN WITHOUT PERMISSION. OFFENDERS WILL BE HELD LIABLE FOR PAYMENT OF DAMAGES. ALL RIGHTS ARE RESERVED IN THE EVENT OF A PATENT GRANT OR REGISTRATION OF A UTILITY MODEL OR DESIGN. Copyright © Quectel Wireless Solutions Co., Ltd. 2014. All rights reserved.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 2 / 80 About the Document History Revision Date Author Description 1.0 2014-08-07 Felix YIN Initial 1.1 2014-11-24 Felix YIN 1. Modified output power of Bluetooth2. Modified the timing of the RFTXMON signal3. Updated Figure 5: Reference circuit for powersupply4. Modified description of RTC and SIM cardinterface5. Modified description of UART Application6. Deleted the over-voltage automatic shutdownfunction7. Modified the antenna gain in the Table 248. Modified the current consumption information inSection 5.3 & 5.4
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 3 / 80 ContentsAbout the Document ................................................................................................................................... 2 Contents ....................................................................................................................................................... 3 Table Index ................................................................................................................................................... 6 Figure Index ................................................................................................................................................. 7 1 Introduction .......................................................................................................................................... 9 1.1. Safety Information.................................................................................................................... 10 2 Product Concept ................................................................................................................................ 11 2.1. General Description ................................................................................................................. 11 2.2. Key Features ........................................................................................................................... 12 2.3. Functional Diagram ................................................................................................................. 14 2.4. Evaluation Board ..................................................................................................................... 14 3 Application Interface ......................................................................................................................... 15 3.1. Pin of Module ........................................................................................................................... 16 3.1.1. Pin Assignment .............................................................................................................. 16 3.1.2. Pin Description ............................................................................................................... 17 3.2. Operating Modes ..................................................................................................................... 21 3.3. Power Supply ........................................................................................................................... 22 3.3.1. Power Features of Module ............................................................................................. 22 3.3.2. Decrease Supply Voltage Drop ...................................................................................... 23 3.3.3. Reference Design For Power Supply ............................................................................ 23 3.3.4. Monitor Power Supply .................................................................................................... 24 3.4. Power On and Down Scenarios .............................................................................................. 24 3.4.1. Power On ....................................................................................................................... 24 3.4.2. Power Down ................................................................................................................... 26 3.4.2.1. Power Down Module Using the PWRKEY Pin .................................................. 26 3.4.2.2. Power Down Module Using AT Command ........................................................ 27 3.4.2.3. Under-voltage Automatic Shutdown .................................................................. 28 3.4.3. Restart ............................................................................................................................ 28 3.5. Power Saving ........................................................................................................................... 29 3.5.1. Minimum Functionality Mode ......................................................................................... 29 3.5.2. SLEEP Mode .................................................................................................................. 29 3.5.3. Wake Up Module From SLEEP Mode ........................................................................... 30 3.5.4. Summary of State Transition .......................................................................................... 30 3.6. RTC Backup............................................................................................................................. 30 3.7. Serial Interfaces ....................................................................................................................... 32 3.7.1. UART Port ...................................................................................................................... 34 3.7.1.1. The Feature of UART Port................................................................................. 34 3.7.1.2. The Connection of UART .................................................................................. 35
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 4 / 80 3.7.1.3. Firmware Upgrade ............................................................................................. 36 3.7.2. Debug Port ..................................................................................................................... 37 3.7.3. Auxiliary UART Port ....................................................................................................... 38 3.7.4. UART Application ........................................................................................................... 38 3.8. Audio Interfaces ....................................................................................................................... 40 3.8.1. Decrease TDD Noise and other Noise .......................................................................... 41 3.8.2. Microphone Interfaces Design ....................................................................................... 41 3.8.3. Receiver and Speaker Interface Design ........................................................................ 42 3.8.4. Earphone Interface Design ............................................................................................ 44 3.8.5. Audio Characteristics ..................................................................................................... 44 3.9. PCM Interface .......................................................................................................................... 45 3.9.1. Configuration .................................................................................................................. 45 3.9.2. Timing ............................................................................................................................. 46 3.9.3. Reference Design .......................................................................................................... 48 3.9.4. AT Command ................................................................................................................. 48 3.10. SIM Card Interface................................................................................................................... 49 3.11. ADC ......................................................................................................................................... 51 3.12. Behaviors of The RI ................................................................................................................. 51 3.13. Network Status Indication ........................................................................................................ 53 3.14. RF Transmitting Signal Indication ............................................................................................ 54 4 Antenna Interface ............................................................................................................................... 56 4.1. GSM Antenna Interface ........................................................................................................... 56 4.1.1. Reference Design .......................................................................................................... 56 4.1.2. RF Output Power ........................................................................................................... 57 4.1.3. RF Receiving Sensitivity ................................................................................................ 58 4.1.4. Operating Frequencies................................................................................................... 58 4.1.5. RF Cable Soldering ........................................................................................................ 59 4.2. Bluetooth Antenna Interface .................................................................................................... 59 5 Electrical, Reliability and Radio Characteristics ............................................................................ 61 5.1. Absolute Maximum Ratings ..................................................................................................... 61 5.2. Operating Temperature ............................................................................................................ 61 5.3. Power Supply Ratings ............................................................................................................. 62 5.4. Current Consumption .............................................................................................................. 63 5.5. Electro-static Discharge ........................................................................................................... 65 6 Mechanical Dimensions .................................................................................................................... 66 6.1. Mechanical Dimensions of Module .......................................................................................... 66 6.2. Recommended Footprint ......................................................................................................... 68 6.3. Top View of the Module ........................................................................................................... 69 6.4. Bottom View of the Module ...................................................................................................... 69 7 Storage and Manufacturing .............................................................................................................. 70 7.1. Storage..................................................................................................................................... 70 7.2. Soldering .................................................................................................................................. 71
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 5 / 80 7.3. Packaging ................................................................................................................................ 71 7.3.1. Tape and Reel Packaging .............................................................................................. 72 8 Appendix A Reference ....................................................................................................................... 73 9 Appendix B GPRS Coding Scheme ................................................................................................. 78 10 Appendix C GPRS Multi-slot Class .................................................................................................. 80 11 FCC Warning ...................................................................................................................................... 81
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 6 / 80 Table Index TABLE 1: MODULE KEY FEATURES ............................................................................................................... 12 TABLE 2: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ........................ 13 TABLE 3: IO PARAMETERS DEFINITION ........................................................................................................ 17 TABLE 4: PIN DESCRIPTION ........................................................................................................................... 17 TABLE 5: OVERVIEW OF OPERATING MODES ............................................................................................. 21 TABLE 6: SUMMARY OF STATE TRANSITION ............................................................................................... 30 TABLE 7: LOGIC LEVELS OF THE UART INTERFACE .................................................................................. 33 TABLE 8: PIN DEFINITION OF THE UART INTERFACES .............................................................................. 33 TABLE 9: PIN DEFINITION OF AUDIO INTERFACE ....................................................................................... 40 TABLE 10: TYPICAL ELECTRET MICROPHONE CHARACTERISTICS ......................................................... 44 TABLE 11: TYPICAL SPEAKER CHARACTERISTICS ..................................................................................... 44 TABLE 12: PIN DEFINITION OF PCM INTERFACE ......................................................................................... 45 TABLE 13: CONFIGURATION ........................................................................................................................... 45 TABLE 14: QPCMON COMMAND DESCRIPTION .......................................................................................... 48 TABLE 15: QPCMVOL COMMAND DESCRIPTION ......................................................................................... 49 TABLE 16: PIN DEFINITION OF THE SIM INTERFACE .................................................................................. 49 TABLE 17: PIN DEFINITION OF THE ADC ...................................................................................................... 51 TABLE 18: CHARACTERISTICS OF THE ADC ................................................................................................ 51 TABLE 19: BEHAVIORS OF THE RI ................................................................................................................. 51 TABLE 20: WORKING STATE OF THE NETLIGHT .......................................................................................... 53 TABLE 21: PIN DEFINITION OF THE RFTXMON ............................................................................................ 54 TABLE 22: PIN DEFINITION OF THE RF_ANT ................................................................................................ 56 TABLE 23: ANTENNA CABLE REQUIREMENTS ............................................................................................. 57 TABLE 24: ANTENNA REQUIREMENTS .......................................................................................................... 57 TABLE 25: THE MODULE CONDUCTED RF OUTPUT POWER .................................................................... 57 TABLE 26: THE MODULE CONDUCTED RF RECEIVING SENSITIVITY ....................................................... 58 TABLE 27: THE MODULE OPERATING FREQUENCIES ................................................................................ 58 TABLE 28: PIN DEFINITION OF THE BT_ANT ................................................................................................ 59 TABLE 29: ABSOLUTE MAXIMUM RATINGS .................................................................................................. 61 TABLE 30: OPERATING TEMPERATURE ........................................................................................................ 61 TABLE 31: THE MODULE POWER SUPPLY RATINGS .................................................................................. 62 TABLE 32: THE MODULE CURRENT CONSUMPTION .................................................................................. 63 TABLE 33: THE ESD ENDURANCE (TEMPERATURE: 25ºC, HUMIDITY: 45%) ............................................ 65 TABLE 34: RELATED DOCUMENTS ................................................................................................................ 73 TABLE 35: TERMS AND ABBREVIATIONS ...................................................................................................... 74 TABLE 36: DESCRIPTION OF DIFFERENT CODING SCHEMES .................................................................. 78 TABLE 37: GPRS MULTI-SLOT CLASSES ...................................................................................................... 80
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 7 / 80 Figure Index FIGURE 1: MODULE FUNCTIONAL DIAGRAM ............................................................................................... 14 FIGURE 2: PIN ASSIGNMENT ......................................................................................................................... 16 FIGURE 3: VOLTAGE RIPPLE DURING TRANSMITTING .............................................................................. 22 FIGURE 4: REFERENCE CIRCUIT FOR THE VBAT INPUT ........................................................................... 23 FIGURE 5: REFERENCE CIRCUIT FOR POWER SUPPLY ............................................................................ 24 FIGURE 6: TURN ON THE MODULE WITH AN OPEN-COLLECTOR DRIVER .............................................. 25 FIGURE 7: TURN ON THE MODULE WITH A BUTTON .................................................................................. 25 FIGURE 8: TURN-ON TIMING .......................................................................................................................... 26 FIGURE 9: TURN-OFF TIMING ........................................................................................................................ 27 FIGURE 10: TIMING OF RESTARTING SYSTEM ............................................................................................ 28 FIGURE 11: VRTC IS SUPPLIED BY A NON-CHARGEABLE BATTERY ........................................................ 31 FIGURE 12: VRTC IS SUPPLIED BY A RECHARGEABLE BATTERY ............................................................ 31 FIGURE 13: VRTC IS SUPPLIED BY A CAPACITOR ...................................................................................... 32 FIGURE 14: REFERENCE DESIGN FOR FULL-FUNCTION UART ................................................................ 35 FIGURE 15: REFERENCE DESIGN FOR UART PORT ................................................................................... 36 FIGURE 16: REFERENCE DESIGN FOR UART PORT WITH HARDWARE FLOW CONTROL .................... 36 FIGURE 17: REFERENCE DESIGN FOR FIRMWARE UPGRADE ................................................................. 37 FIGURE 18: REFERENCE DESIGN FOR DEBUG PORT ............................................................................... 37 FIGURE 19: REFERENCE DESIGN FOR AUXILIARY UART PORT ............................................................... 38 FIGURE 20: LEVEL MATCH DESIGN FOR 3.3V SYSTEM .............................................................................. 38 FIGURE 21: SKETCH MAP FOR RS-232 INTERFACE MATCH ...................................................................... 39 FIGURE 22: REFERENCE DESIGN FOR AIN ................................................................................................. 41 FIGURE 23: HANDSET INTERFACE DESIGN FOR AOUT1 ........................................................................... 42 FIGURE 24: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT1 ....................................... 42 FIGURE 25: HANDSET INTERFACE DESIGN FOR AOUT2 ........................................................................... 43 FIGURE 26: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT2 ....................................... 43 FIGURE 27: EARPHONE INTERFACE DESIGN .............................................................................................. 44 FIGURE 28: LONG SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ................................................... 46 FIGURE 29: LONG SYNCHRONIZATION & ZERO PADDING DIAGRAM....................................................... 47 FIGURE 30: SHORT SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ................................................. 47 FIGURE 31: SHORT SYNCHRONIZATION & ZERO PADDING DIAGRAM .................................................... 47 FIGURE 32: REFERENCE DESIGN FOR PCM ............................................................................................... 48 FIGURE 33: REFERENCE CIRCUIT FOR SIM INTERFACE WITH THE 6-PIN SIM CARD HOLDER ........... 50 FIGURE 34: RI BEHAVIOR OF VOICE CALLING AS A RECEIVER ................................................................ 52 FIGURE 35: RI BEHAVIOR AS A CALLER ....................................................................................................... 52 FIGURE 36: RI BEHAVIOR OF URC OR SMS RECEIVED ............................................................................. 52 FIGURE 37: REFERENCE DESIGN FOR NETLIGHT ..................................................................................... 53 FIGURE 38: RFTXMON SIGNAL DURING BURST TRANSMISSION ............................................................. 54 FIGURE 39: RFTXMON SIGNAL DURING CALL ............................................................................................. 55 FIGURE 40: REFERENCE DESIGN FOR GSM ANTENNA ............................................................................. 56 FIGURE 41: RF SOLDERING SAMPLE ........................................................................................................... 59
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 8 / 80 FIGURE 42: REFERENCE DESIGN FOR BLUETOOTH ANTENNA ............................................................... 60 FIGURE 43: M26 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM) ......................................................... 66 FIGURE 44: M26 MODULE BOTTOM DIMENSIONS (UNIT: MM) ................................................................... 67 FIGURE 45: RECOMMENDED FOOTPRINT (UNIT: MM) ................................................................................ 68 FIGURE 46: TOP VIEW OF THE MODULE ...................................................................................................... 69 FIGURE 47: BOTTOM VIEW OF THE MODULE .............................................................................................. 69 FIGURE 48: RAMP-SOAK-SPIKE REFLOW PROFILE .................................................................................... 71 FIGURE 49: TAPE AND REEL SPECIFICATION .............................................................................................. 72 FIGURE 50: DIMENSIONS OF REEL ............................................................................................................... 72 FIGURE 51: RADIO BLOCK STRUCTURE OF CS-1, CS-2 AND CS-3 ........................................................... 78 FIGURE 52: RADIO BLOCK STRUCTURE OF CS-4 ....................................................................................... 79
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 9 / 80 1 Introduction This document defines the M26 module and describes its hardware interface which are connected with the customer application and the air interface. This document can help you quickly understand module interface specifications, electrical and mechanical details. Associated with application note and user guide, you can use M26 module to design and set up mobile applications easily.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 10 / 80 1.1. Safety Information The following safety precautions must be observed during all phases of the operation, such as usage, service or repair of any cellular terminal or mobile incorporating M26 module. Manufacturers of the cellular terminal should send the following safety information to users and operating personnel and to incorporate these guidelines into all manuals supplied with the product. If not so, Quectel does not take on any liability for customer failure to comply with these precautions. Full attention must be given to driving at all times in order to reduce the risk of an accident. Using a mobile while driving (even with a handsfree kit) cause distraction and can lead to an accident. You must comply with laws and regulations restricting the use of wireless devices while driving. Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it switched off. The operation of wireless appliances in an aircraft is forbidden to prevent interference with communication systems. Consult the airline staff about the use of wireless devices on boarding the aircraft, if your device offers a Airplane Mode which must be enabled prior to boarding an aircraft. Switch off your wireless device when in hospitals or clinics or other health care facilities. These requests are desinged to prevent possible interference with sentitive medical equipment. Cellular terminals or mobiles operate over radio frequency signal and cellular network and cannot be guaranteed to connect in all conditions, for example no mobile fee or an invalid SIM card. While you are in this condition and need emergent help, please remember using emergency call. In order to make or receive call, the cellular terminal or mobile must be switched on and in a service area with adequate cellular signal strength. Your cellular terminal or mobile contains a transmitter and receiver. When it is ON , it receives and transmits radio frequency energy. RF interference can occur if it is used close to TV set, radio, computer or other electric equipment. In locations with potencially explosive atmospheres, obey all posted signs to turn off wireless devices such as your phone or other cellular terminals. Areas with potencially exposive atmospheres including fuelling areas, below decks on boats, fuel or chemical transfer or storage facilities, areas where the air contains chemicals or particles such as grain, dust or metal powders.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 11 / 80 2 Product Concept 2.1. General Description M26 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz, DCS1800MHz and PCS1900MHz. The M26 features GPRS multi-slot class 12 and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. For more details about GPRS multi-slot classes and coding schemes, please refer to the Appendix B & C. With a tiny profile of 15.8mm × 17.7mm × 2.3mm, the module can meet almost all the requirements for M2M applications, including Vehicles and Personal Tracking, Security System, Wireless POS, Industrial PDA, Smart Metering, and Remote Maintenance& Control, etc. M26 is an SMD type module with LCC package, which can be easily embedded into applications. It provides abundant hardware interfaces like PCM Interface. Designed with power saving technique, the current consumption of M26 is as low as 1.3 mA in SLEEP mode when DRX is 5. M26 is integrated with Internet service protocols, such as TCP/UDP, FTP and PPP. Extended AT commands have been developed for you to use these Internet service protocols easily. M26 supports Bluetooth interface, it is fully compliant with Bluetooth specification 3.0. The module fully complies with the RoHS directive of the European Union.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 12 / 80 2.2. Key Features The following table describes the detailed features of M26 module. Table 1: Module Key Features Feature Implementation Power Supply Single supply voltage: 3.3V ~ 4.6V Typical supply voltage: 4V Power Saving Typical power consumption in SLEEP mode: 1.3 mA @DRX=5 1.2 mA @DRX=9 Frequency Bands  Quad-band: GSM850, EGSM900, DCS1800, PCS1900.  The module can search these frequency bands automatically  The frequency bands can be set by AT command  Compliant to GSM Phase 2/2+ GSM Class Small MS Transmitting Power  Class 4 (2W) at GSM850 and EGSM900  Class 1 (1W) at DCS1800 and PCS1900 GPRS Connectivity  GPRS multi-slot class 12 (default)  GPRS multi-slot class 1~12 (configurable)  GPRS mobile station class B DATA GPRS  GPRS data downlink transfer: max. 85.6kbps  GPRS data uplink transfer: max. 85.6kbps  Coding scheme: CS-1, CS-2, CS-3 and CS-4  Support the protocols PAP (Password Authentication Protocol) usually used for PPP connections  Internet service protocols TCP/UDP, FTP, PPP, HTTP, NTP, PING  Support Packet Broadcast Control Channel (PBCCH)  Support Unstructured Supplementary Service Data (USSD) Temperature Range  Normal operation: -35°C ~ +80°C  Restricted operation: -40°C ~ -35°C and +80°C ~ +85°C 1)  Storage temperature: -45°C ~ +90°C Bluetooth  Support Bluetooth specification 3.0  Output Power: Class 1 (Typical 7.5dBm) SMS  Text and PDU mode  SMS storage: SIM card SIM Interface Support SIM card: 1.8V, 3.0V Audio Features Speech codec modes:  Half Rate (ETS 06.20)  Full Rate (ETS 06.10)
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 13 / 80 1) When the module works within this temperature range, the deviations from the GSM specification may occur. For example, the frequency error or the phase error will be increased. Table 2: Coding Schemes and Maximum Net Data Rates over Air Interface  Enhanced Full Rate (ETS 06.50/06.60/06.80)  Adaptive Multi-Rate (AMR)  Echo Suppression  Noise Reduction UART Interfaces UART Port:  Seven lines on UART port interface  Used for AT command, GPRS data  Multiplexing function  Support autobauding from 4800bps to 115200bps Debug Port:  Two lines on debug port interface DBG_TXD and DBG_RXD  Debug Port only used for firmware debugging Auxiliary Port:  Used for AT command Phonebook Management Support phonebook types: SM, ME, ON, MC, RC, DC, LD, LA SIM Application Toolkit Support SAT class 3, GSM 11.14 Release 99 Real Time Clock Supported Physical Characteristics Size: 15.8±0.15 × 17.7±0.15 × 2.3±0.2mm Weight: Approx. 1.3g Firmware Upgrade Firmware upgrade via UART Port Antenna Interface Connected to antenna pad with 50 Ohm impedance control Coding Scheme 1 Timeslot 2 Timeslot 4 Timeslot CS-1 9.05kbps 18.1kbps 36.2kbps CS-2 13.4kbps 26.8kbps 53.6kbps CS-3 15.6kbps 31.2kbps 62.4kbps CS-4 21.4kbps 42.8kbps 85.6kbps NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 14 / 80 2.3. Functional Diagram The following figure shows a block diagram of M26 and illustrates the major functional parts.  Radio frequency part  Power management  The peripheral interface —Power supply —Turn-on/off interface —UART interface —Audio interface —PCM interface —SIM interface —ADC interface —RF interface —BT interface BB&RFRF PAM26MHzRF TransceiverRTCAUDIOSerial InterfaceSIM InterfaceRF_ANTVBATPWRKEYVRTCNETLIGHTUARTSIM Interface ESDPMUMEMORYBT_ANTPWMAUDIOPCM PCMADC ADCBTVDD_EXTVDD_EXT Figure 1: Module Functional Diagram 2.4. Evaluation Board In order to help you to develop applications with M26, Quectel supplies an evaluation board (EVB), RS-232 to USB cable, power adapter, earphone, antenna and other peripherals to control or test the module. For details, please refer to the document [11].
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 15 / 80 3 Application Interface The module adopts LCC package and has 44 pins. The following chapters provide detailed descriptions about these pins.  Pin of module  Operating modes  Power supply  Power on/down  Power saving  RTC  Serial interfaces  Audio interfaces  PCM interface  SIM card interface  ADC  Behaviors of the RI  Network status indication  RF transmitting signal indication
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 16 / 80 3.1. Pin of Module 3.1.1. Pin Assignment AGNDSPK2PMICPMICNSPK1PSPK1NPWRKEYSIM_RSTSIM_CLKCTSVRTCVBATGNDGNDDBG_TXDDBG_RXDGNDGNDRF_ANT14M26 Top View1516171819202122 36373839404142434412345678910111213 23242526272829303132333435AVDDADC0SIM_GNDSIM_DATAGNDPCM_OUTPCM_INPCM_SYNCPCM_CLKTXD_AUXRXD_AUXGNDBT_ANTRFTXMONVDD_EXTRTSDCDRIDTRTXDRXDNETLIGHTRESERVEDSIM_VDDVBATPOWER GND AUDIO UART SIM PCM ANT OTHERSRESERVED Figure 2: Pin Assignment Keep all reserved pins open. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 17 / 80 3.1.2. Pin Description Table 3: IO Parameters Definition Type Description IO Bidirectional input/output DI Digital input DO Digital output PI Power input PO Power output AI Analog input AO Analog output Table 4: Pin Description Power Supply PIN Name PIN No. I/O Description DC Characteristics Comment VBAT 42,43 PI Main power supply of module: VBAT=3.3V~4.6V VImax=4.6V VImin=3.3V VInorm=4.0V Make sure that supply sufficient current in a transmitting burst typically rises to 1.6A. VRTC 44 IO Power supply for RTC when VBAT is not supplied for the system. Charging for backup battery or golden capacitor when the VBAT is applied. VImax=3.3V VImin=1.5V VInorm=2.8V VOmax=3V VOmin=2V VOnorm=2.8V IOmax=2mA Iin≈10uA If unused, keep this pin open. VDD_ EXT 24 PO Supply 2.8V voltage for external circuit. VOmax=2.9V VOmin=2.7V VOnorm=2.8V IOmax=20mA 1. If unused, keep this pin open. 2. Recommend to add a
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 18 / 80 2.2~4.7uF bypass capacitor, when using this pin for power supply. GND 27,34 36,37 40,41 Ground Turn on/off PIN Name PIN No. I/O Description DC Characteristics Comment PWRKEY 7 DI Power on/off key. PWRKEY should be pulled down for a moment to turn on or turn off the system. VILmax= 0.1×VBAT VIHmin= 0.6×VBAT VIHmax=3.1V Audio Interface PIN Name PIN No. I/O Description DC Characteristics Comment MICP MICN 3, 4 AI Positive and negative voice input Refer to Section 3.8 If unused, keep these pins open. SPK1P SPK1N 5, 6 AO Channel 1 positive and negative voice output If unused, keep these pins open. Support both voice and ringtone output. SPK2P 2 AO Channel 2 voice output AGND 1 Analog ground. Separate ground connection for external audio circuits. If unused, keep this pin open. Network Status Indicator PIN Name PIN No. I/O Description DC Characteristics Comment NETLIGHT 16 DO Network status indication VOHmin= 0.85×VDD_EXT VOLmax= 0.15×VDD_EXT If unused, keep this pin open. UART Port PIN Name PIN No. I/O Description DC Characteristics Comment
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 19 / 80 TXD 18 DO Transmit data VILmin=0V VILmax= 0.25×VDD_EXT VIHmin= 0.75×VDD_EXT VIHmax= VDD_EXT+0.2 VOHmin= 0.85×VDD_EXT VOLmax= 0.15×VDD_EXT If only use TXD, RXD and GND to communicate, recommended to keep other pins open. RXD 17 DI Receive data DTR 19 DI Data terminal ready RI 20 DO Ring indication DCD 21 DO Data carrier detection CTS 22 DO Clear to send RTS 23 DI Request to send Debug Port PIN Name PIN No. I/O Description DC Characteristics Comment DBG_ TXD 39 DO Transmit data Same as above If unused, keep these pins open. DBG_ RXD 38 DI Receive data Auxiliary Port PIN Name PIN No. I/O Description DC Characteristics Comment TXD_ AUX 29 DO Transmit data Same as above If unused, keep these pins open. RXD_ AUX 28 DI Receive data SIM Interface PIN Name PIN No. I/O Description DC Characteristics Comment SIM_ VDD 14 PO Power supply for SIM card The voltage can be selected by software automatically. Either 1.8V or 3.0V. All signals of SIM interface should be protected against ESD with a TVS diode array. Maximum trace length is 200mm from the module pad to SIM card holder. SIM_ CLK 13 DO SIM clock VOLmax= 0.15×SIM_VDD VOHmin= 0.85×SIM_VDD SIM_ DATA 11 IO SIM data VILmax= 0.25×SIM_VDD VIHmin= 0.75×SIM_VDD VOLmax= 0.15×SIM_VDD VOHmin= 0.85×SIM_VDD
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 20 / 80 SIM_ RST 12 DO SIM reset VOLmax= 0.15×SIM_VDD VOHmin= 0.85×SIM_VDD SIM_ GND 10 SIM ground ADC PIN Name PIN No. I/O Description DC Characteristics Comment AVDD 8 PO Reference voltage of ADC circuit VOmax=2.9V VOmin=2.7V VOnorm=2.8V If unused, keep this pin open. ADC0 9 AI General purpose analog to digital converter. Voltage range: 0V to 2.8V If unused, keep this pin open. PCM PIN Name PIN No. I/O Description DC Characteristics Comment PCM_ CLK 30 DO PCM clock VILmin= 0V VILmax= 0.25×VDD_EXT VIHmin= 0.75×VDD_EXT VIHmax= VDD_EXT+0.2 VOHmin= 0.85×VDD_EXT VOLmax= 0.15×VDD_EXT If unused, keep this pin open. PCM_ SYNC 31 DO PCM frame synchronization PCM_ IN 32 DI PCM data input PCM_ OUT 33 DO PCM data output Antenna Interface PIN Name PIN No. I/O Description DC Characteristics Comment RF_ ANT 35 IO GSM antenna pad Impedance of 50Ω BT_ ANT 26 IO BT antenna pad Impedance of 50Ω If unused, keep this pin open. Transmitting Signal Indication PIN Name PIN No. I/O Description DC Characteristics Comment RFTXMON 25 DO Transmission signal indication VOHmin= 0.85×VDD_EXT VOLmax= If unused, keep this pin open.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 21 / 80 3.2. Operating Modes The table below briefly summarizes the various operating modes in the following chapters. Table 5: Overview of Operating Modes 0.15×VDD_EXT Other Interface PIN Name PIN No. I/O Description DC Characteristics Comment RESERVED 15 Keep these pins open. Mode Function Normal Operation GSM/GPRS Sleep After enabling sleep mode by AT+QSCLK=1, the module will automatically enter into Sleep Mode if DTR is set to high level and there is no interrupt (such as GPIO interrupt or data on UART port). In this case, the current consumption of module will reduce to the minimal level. During Sleep Mode, the module can still receive paging message and SMS from the system normally. GSM IDLE Software is active. The module has registered to the GSM network, and the module is ready to send and receive GSM data. GSM TALK GSM connection is ongoing. In this mode, the power consumption is decided by the configuration of Power Control Level (PCL), dynamic DTX control and the working RF band. GPRS IDLE The module is not registered to GPRS network. The module is not reachable through GPRS channel. GPRS STANDBY The module is registered to GPRS network, but no GPRS PDP context is active. The SGSN knows the Routing Area where the module is located at. GPRS READY The PDP context is active, but no data transfer is ongoing. The module is ready to receive or send GPRS data. The SGSN knows the cell where the module is located at. GPRS DATA There is GPRS data in transfer. In this mode, power consumption is decided by the PCL, working RF band and GPRS multi-slot configuration.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 22 / 80 3.3. Power Supply 3.3.1. Power Features of Module The power supply is one of the key issues in designing GSM terminals. Because of the 577us radio burst in GSM every 4.615ms, power supply must be able to deliver high current peaks in a burst period. During these peaks, drops on the supply voltage must not exceed minimum working voltage of module. For the M26 module, the max current consumption could reach to 1.6A during a burst transmission. It will cause a large voltage drop on the VBAT. In order to ensure stable operation of the module, it is recommended that the max voltage drop during the burst transmission does not exceed 400mV. Vdrop4.615ms577usIBATVBATBurst:1.6A Figure 3: Voltage Ripple during Transmitting POWER DOWN Normal shutdown by sending the AT+QPOWD=1 command or using the PWRKEY pin. The power management ASIC disconnects the power supply from the base band part of the module, and only the power supply for the RTC is remained. Software is not active. The UART interfaces are not accessible. Operating voltage (connected to VBAT) remains applied. Minimum Functionality Mode (without removing power supply) AT+CFUN command can set the module to a minimum functionality mode without removing the power supply. In this case, the RF part of the module will not work or the SIM card will not be accessible, or both RF part and SIM card will be disabled, but the UART port is still accessible. The power consumption in this case is very low.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 23 / 80 3.3.2. Decrease Supply Voltage Drop The power supply range of the module is 3.3V to 4.6V. Make sure that the input voltage will never drop below 3.3V even in a burst transmission. If the power voltage drops below 3.3V, the module could turn off automatically. For better power performance, it is recommended to place a 100uF tantalum capacitor with low ESR (ESR=0.7Ω) and ceramic capacitor 100nF, 33pF and 10pF near the VBAT pin. The reference circuit is illustrated in Figure 4. The VBAT route should be wide enough to ensure that there is not too much voltage drop during burst transmission. The width of trace should be no less than 2mm and the principle of the VBAT route is the longer route, the wider trace. VBATC2C1+C3 C4GND100uF 100nF 10pF060333pF0603 Figure 4: Reference Circuit for the VBAT Input 3.3.3. Reference Design For Power Supply The power design for the module is very important, since the performance of power supply for the module largely depends on the power source. The power supply is capable of providing the sufficient current up to 2A at least. If the voltage drop between the input and output is not too high, it is suggested to use a LDO as module’s power supply. If there is a big voltage difference between the input source and the desired output (VBAT), a switcher power converter is recommended to use as a power supply. The following figure shows a reference design for +5V input power source. The designed output for the power supply is 4.0V and the maximum load current is 3A. In addition, in order to get a stable output voltage, a zener diode is placed close to the pins of VBAT. As to the zener diode, it is suggested to use a zener diode whose reverse zener voltage is 5.1V and dissipation power is more than 1 Watt.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 24 / 80 DC_INC1 C2MIC29302WU U1IN OUTENGNDADJ2 4135VBAT 100nFC3470uFC4100nFR2D1124K56KR3470uF 5.1VR4470RMCU_POWER_ON/OFF47K4.7KR5R6R151K Figure 5: Reference Circuit for Power Supply It is suggested to control the module’s main power supply (VBAT) via LDO enable pin to restart the module when the module has become abnormal. Power switch circuit like P-channel MOSFET switch circuit can also be used to control VBAT. 3.3.4. Monitor Power Supply The command ―AT+CBC‖ can be used to monitor the supply voltage of the module. The unit of the displayed voltage is mV. For details, please refer to the document [1]. 3.4. Power On and Down Scenarios 3.4.1. Power On The module can be turned on by driving the pin PWRKEY to a low level voltage. An open collector driver circuit is suggested to control the PWRKEY. A simple reference circuit is illustrated as below. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 25 / 80 Turn on pulsePWRKEY4.7K47K Figure 6: Turn on the Module with an Open-collector Driver 1. M26 module is set to autobauding mode (AT+IPR=0) by default. In the autobauding mode, URC ―RDY‖ is not reported to the host controller after module is powered on. When the module is powered on after a delay of 4 or 5 seconds, it can receive AT command. Host controller should first send an AT string in order that the module can detect baud rate of host controller, and it should continue to send the next AT string until receiving OK string from the module. Then enter AT+IPR=x;&W to set a fixed baud rate for the module and save the configuration to flash memory of the module. After these configurations, the URC RDY would be received from the UART Port of the module every time when the module is powered on. For more details, refer to the section AT+IPR in document [1]. 2. When AT command is responded, indicates module is turned on successfully, or else the module fails to be turned on. The other way to control the PWRKEY is through a button directly. A TVS component is indispensable to be placed nearby the button for ESD protection. For the best performance, the TVS component must be placed nearby the button. When pressing the key, electrostatic strike may generate from finger. A reference circuit is shown in the following figure. PWRKEYS1Close to S1TVS Figure 7: Turn on the Module with a Button NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 26 / 80 The turn-on timing is illustrated as the following figure. VDD_EXT(OUTPUT)VIL<0.1*VBATVIH > 0.6*VBATVBATPWRKEY(INPUT)54ms>1sT1OFF BOOTINGMODULE STATUS RUNNING Figure 8: Turn-on Timing Make sure that VBAT is stable before pulling down PWRKEY pin. The time of T1 is recommended to be 100ms. 3.4.2. Power Down The following procedures can be used to turn off the module:  Normal power down procedure: Turn off module using the PWRKEY pin  Normal power down procedure: Turn off module using command AT+QPOWD  Under-voltage automatic shutdown: Take effect when under-voltage is detected. 3.4.2.1. Power Down Module Using the PWRKEY Pin It is a safe way to turn off the module by driving the PWRKEY to a low level voltage for a certain time. The power down scenario is illustrated below. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 27 / 80 VBATPWRKEY(INPUT)VDD_EXT (OUTPUT)Logout net about 2s to 12s0.7s<Pulldown<1s Figure 9: Turn-off Timing The power down procedure causes the module to log off from the network and allows the firmware to save important data before completely disconnecting the power supply. Before the completion of the power down procedure, the module sends out the result code shown below: NORMAL POWER DOWN After that moment, no further AT commands can be executed. Then the module enters the power down mode, the RTC is still active. 1. This unsolicited result codes do not appear when autobauding is active and DTE and DCE are not correctly synchronized after start-up. The module is recommended to set to a fixed baud rate. 2. As logout network time is related to the local mobile network, it is recommended to delay about 12 seconds before disconnecting the power supply or restarting the module. 3.4.2.2. Power Down Module Using AT Command It is also a safe way to turn off the module via AT command AT+QPOWD=1. This command will let the module log off from the network and allow the firmware to save important data before completely disconnecting the power supply. Before the completion of the power down procedure the module sends out the result code shown below: NORMAL POWER DOWN After that moment, no further AT commands can be executed. And then the module enters the power down mode, only the RTC is still active. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 28 / 80 Please refer to the document [1] for details about the AT command AT+QPOWD. 3.4.2.3. Under-voltage Automatic Shutdown The module will constantly monitor the voltage applied on the VBAT, if the voltage is ≤3.5V, the following URC will be presented: UNDER_VOLTAGE WARNING The normal input voltage range is from 3.3V to 4.6V. If the voltage is <3.3V, the module would automatically shut down itself. If the voltage is <3.3V, the following URC will be presented: UNDER_VOLTAGE POWER DOWN After that moment, no further AT commands can be executed. The module logs off from network and enters power down mode, and only RTC is still active. These unsolicited result codes do not appear when autobauding is active and DTE and DCE are not correctly synchronized after start-up. The module is recommended to set to a fixed baud rate. 3.4.3. Restart You can restart the module by driving the PWRKEY to a low level voltage for a certain time, which is similar to the way of turning on module. In order to make the internal LDOs discharge completely after turning off the module, it is recommended to delay about 500ms before restarting the module. The restart timing is illustrated as the following figure. PWRKEY(INPUT)VDD_EXT(OUTPUT)Turn off RestartPull down the PWRKEY to turn on the moduleDelay >0.5s Figure 10: Timing of Restarting System NOTES
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 29 / 80 3.5. Power Saving Based on system requirements, there are several actions to drive the module to enter low current consumption status. For example, AT+CFUN can be used to set module into minimum functionality mode and DTR hardware interface signal can be used to lead system to SLEEP mode. 3.5.1. Minimum Functionality Mode Minimum functionality mode reduces the functionality of the module to a minimum level. The consumption of the current can be minimized when the slow clocking mode is activated at the same time. The mode is set with the AT+CFUN command which provides the choice of the functionality levels <fun>=0, 1, 4.  0: minimum functionality  1: full functionality (default)  4: disable both transmitting and receiving of RF part If the module is set to minimum functionality by AT+CFUN=0, the RF function and SIM card function would be disabled. In this case, the UART port is still accessible, but all AT commands related with RF function or SIM card function will be not available. If the module has been set by the command with AT+CFUN=4, the RF function will be disabled, but the UART port is still active. In this case, all AT commands related with RF function will be not available. After the module is set by AT+CFUN=0 or AT+CFUN=4, it can return to full functionality by AT+CFUN=1. For detailed information about AT+CFUN, please refer to the document [1]. 3.5.2. SLEEP Mode The SLEEP mode is disabled by default. You can enable it by AT+QSCLK=1. On the other hand, the default setting is AT+QSCLK=0 and in this mode, the module cannot enter SLEEP mode. When the module is set by the command with AT+QSCLK=1, you can control the module to enter or exit from the SLEEP mode through pin DTR. When DTR is set to high level, and there is no on-air or hardware interrupt such as GPIO interrupt or data on UART port, the module will enter SLEEP mode automatically. In this mode, the module can still receive voice, SMS or GPRS paging from network, but the UART port does not work.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 30 / 80 3.5.3. Wake Up Module From SLEEP Mode When the module is in the SLEEP mode, the following methods can wake up the module.  If the DTR Pin is set low, it would wake up the module from the SLEEP mode. The UART port will be active within 20ms after DTR is changed to low level.  Receive a voice or data call from network wakes up module.  Receive an SMS from network wakes up module. DTR pin should be held at low level during communication between the module and DTE. 3.5.4. Summary of State Transition Table 6: Summary of State Transition 3.6. RTC Backup The RTC (Real Time Clock) function is supported. The RTC is designed to work with an internal power supply. There are three kinds of designs for RTC backup power:  Use VBAT as the RTC power source. When the module is turned off and the main power supply (VBAT) is remained, the real time clock is still active as the RTC core is supplied by VBAT. In this case, the VRTC pin can be kept floating. Current Mode Next Mode Power Down Normal Mode Sleep Mode Power Down Use PWRKEY Normal Mode AT+QPOWD, use PWRKEY pin Use AT command AT+QSCLK=1 and pull up DTR SLEEP Mode Use PWRKEY pin Pull DTR down or incoming call or SMS or GPRS NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 31 / 80  Use VRTC as the RTC power source. If the main power supply (VBAT) is removed after the module is turned off, a backup supply such as a coin-cell battery (rechargeable or non-chargeable) or a super-cap can be used to supply the VRTC pin to keep the real time clock active.  Use VBAT and VRTC as the RTC power source. As only powering the VRTC pin to keep the RTC will lead an error about 5 minutes a day, it is recommended to power VBAT and VRTC pin at the same time when RTC function is needed. The recommended supply for RTC core circuits are shown as below. Non-chargeable Backup BatteryModuleRTC CoreVBATPower SupplyLDO/DCDC LDOVRTC 1.5K Figure 11: VRTC is Supplied by a Non-chargeable Battery Rechargeable Backup BatteryModuleRTC CoreVBATPower SupplyLDO/DCDC LDOVRTC 1.5K Figure 12: VRTC is Supplied by a Rechargeable Battery
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 32 / 80 ModuleRTC CoreVBATPower SupplyLDO/DCDC LDOVRTC 1.5KLarge Capacitance Capacitor Figure 13: VRTC is Supplied by a Capacitor A rechargeable or non-chargeable coin-cell battery can also be used here, for more information, please visit http://www.sii.co.jp/en/. If you want to keep an accurate real time, please keep the main power supply VBAT alive. 3.7. Serial Interfaces The module provides three serial ports: UART Port, Debug Port and Auxiliary UART Port. The module is designed as a DCE (Data Communication Equipment), following the traditional DCE-DTE (Data Terminal Equipment) connection. Autobauding function supports baud rate from 4800bps to 115200bps. The UART Port:  TXD: Send data to RXD of DTE.  RXD: Receive data from TXD of DTE.  RTS: Request to send.  CTS: Clear to send.  DTR: DTE is ready and inform DCE (this pin can wake the module up).  RI: Ring indicator (when there is a call, SMS or URC output, the module will inform DTE with the RI  pin).  DCD: Data carrier detection (the validity of this pin demonstrates the communication link is set up). NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 33 / 80 Hardware flow control is disabled by default. When hardware flow control is required, RTS and CTS should be connected to the host. AT command AT+IFC=2,2 is used to enable hardware flow control. AT command AT+IFC=0,0 is used to disable the hardware flow control. For more details, please refer to the document [1]. The Debug Port:  DBG_TXD: Send data to the COM port of computer.  DBG_RXD: Receive data from the COM port of computer. The Auxiliary UART Port:  TXD_AUX: Send data to the RXD of DTE.  RXD_AUX: Receive data from the TXD of DTE. The logic levels are described in the following table. Table 7: Logic Levels of the UART Interface Table 8: Pin Definition of the UART Interfaces Parameter Min. Max. Unit VIL 0 0.25×VDD_EXT V VIH 0.75×VDD_EXT VDD_EXT +0.2 V VOL 0 0.15×VDD_EXT V VOH 0.85×VDD_EXT VDD_EXT V Interface Pin Name Pin No. Description UART Port TXD 18 Transmit data RXD 17 Receive data DTR 19 Data terminal ready RI 20 Ring indication NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 34 / 80 3.7.1. UART Port 3.7.1.1. The Feature of UART Port  Seven lines on UART interface  Contain data lines TXD and RXD, hardware flow control lines RTS and CTS, other control lines DTR, DCD and RI.  Used for AT command, GPRS data, etc. Multiplexing function is supported on the UART Port. So far only the basic mode of multiplexing is available.  Support the communication baud rates as the following: 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200.  The default setting is autobauding mode. Support the following baud rates for Autobauding function: 4800, 9600, 19200, 38400, 57600, 115200.  The module disables hardware flow control by default. AT command AT+IFC=2,2 is used to enable hardware flow control. After setting a fixed baud rate or autobauding, please send ―AT‖ string at that rate. The UART port is ready when it responds ―OK‖. Autobauding allows the module to detect the baud rate by receiving the string ―AT‖ or ―at‖ from the host or PC automatically, which gives module flexibility without considering which baud rate is used by the host controller. Autobauding is enabled by default. To take advantage of the autobauding mode, special attention should be paid according to the following requirements: Synchronization between DTE and DCE: When DCE (the module) powers on with the autobauding enabled, it is recommended to wait 2 to 3 seconds before sending the first AT character. After receiving the ―OK‖ response, DTE and DCE are correctly synchronized. DCD 21 Data carrier detection CTS 22 Clear to send RTS 23 Request to send Debug Port DBG_RXD 38 Receive data DBG_TXD 39 Transmit data Auxiliary UART Port RXD_AUX 28 Receive data TXD_AUX 29 Transmit data
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 35 / 80 If the host controller needs URC in the mode of autobauding, it must be synchronized firstly. Otherwise the URC will be discarded. Restrictions on autobauding operation:  The UART port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).  The ―At‖ and ―aT‖ commands cannot be used.  Only the strings ―AT‖ or ―at‖ can be detected (neither ―At‖ nor ―aT‖).  The Unsolicited Result Codes like RDY, +CFUN: 1 and +CPIN: READY will not be indicated when the module is turned on with autobauding enabled and not be synchronized.  Any other Unsolicited Result Codes will be sent at the previous baud rate before the module detects the new baud rate by receiving the first ―AT‖ or ―at‖ string. The DTE may receive unknown characters after switching to new baud rate.  It is not recommended to switch to autobauding from a fixed baud rate.  If autobauding is active it is not recommended to switch to multiplex mode. To assure reliable communication and avoid any problems caused by undetermined baud rate between DCE and DTE, it is strongly recommended to configure a fixed baud rate and save it instead of using autobauding after start-up. For more details, please refer to the Section AT+IPR in document [1]. 3.7.1.2. The Connection of UART The connection between module and host using UART Port is very flexible. Three connection styles are illustrated as below. Reference design for Full-Function UART connection is shown as below when it is applied in modulation-demodulation. TXDRXDRTSCTSDTRDCDRITXDRXDRTSCTSDTRDCDRINGModule (DCE)Serial portUART portGND GNDPC (DTE) Figure 14: Reference Design for Full-Function UART NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 36 / 80 Three-line connection is shown as below. TXDRXDGNDUART portTXDRXDGNDModule (DCE) Host (DTE)Controller Figure 15: Reference Design for UART Port UART Port with hardware flow control is shown as below. This connection will enhance the reliability of the mass data communication. RTSCTSRTSCTSGNDRXDTXD TXDRXDGNDModule (DCE) Host (DTE) Controller Figure 16: Reference Design for UART Port with Hardware Flow Control 3.7.1.3. Firmware Upgrade The TXD, RXD can be used to upgrade firmware. The PWRKEY pin must be pulled down before firmware upgrade. The reference circuit is shown as below:
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 37 / 80 IO Connector TXDRXDGNDPWRKEY Module (DCE) UART portTXDRXDGNDPWRKEY Figure 17: Reference Design for Firmware Upgrade The firmware of module might need to be upgraded due to certain reasons. It is recommended to reserve these pins in the host board for firmware upgrade. 3.7.2. Debug Port  Two lines: DBG_TXD and DBG_RXD.  It outputs log information automatically.  Debug Port is only used for firmware debugging and its baud rate must be configured as 460800bps. PeripheralTXDRXDGND Module DBG_TXDDBG_RXD GND Figure 18: Reference Design for Debug Port NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 38 / 80 3.7.3. Auxiliary UART Port  Two data lines: TXD_AUX and RXD_AUX.  Auxiliary UART port is used for AT command only and does not support GPRS data, Multiplexing function etc.  Auxiliary UART port supports the communication baud rates as the following: 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200.  Auxiliary UART port could be used when you send AT+QEAUART=1 string on the UART port.  The default baud rate setting is 115200bps, and does not support autobauding. The baud rate can be modified by AT+QSEDCB command. For more details, please refer to the document [1]. PeripheralTXDRXDGND Module TXD_AUXRXD_AUX GND Figure 19: Reference Design for Auxiliary UART Port 3.7.4. UART Application The reference design of 3.3V level match is shown as below. If the host is a 3V system, please change the 5.6K resistor to 10K. Peripheral/TXD/RXD1KTXDRXDRTSCTSDTRRI/RTS/CTSGPIOEINTGPIO DCDModule1K1KVoltage level:3.3V5.6K5.6K5.6K1K1K1K1KGND GND Figure 20: Level Match Design for 3.3V System
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 39 / 80 It is highly recommended to add the resistor divider circuit on the UART signal lines when the host’s level is 3V or 3.3V. For the higher voltage level system, a level shifter IC could be used between the host and the module. For more details about UART circuit design, please refer to document [13]. The following figure shows a sketch map between module and standard RS-232 interface. Since the electrical level of module is 2.8V, so a RS-232 level shifter must be used. Note that you should assure the IO voltage of level shifter which connects to module is 2.8V. TXDRXDRTSCTSDTRRIDCDModuleGNDC1+C1-C2+C2-V+VCCGNDV-3.3VT1INT2INT3INT4INR1INR2INR3INR1OUTR2OUTR3OUTT1OUTT2OUTT5OUTT3OUTT4OUTT5INGNDGND/R1OUT123456789GNDTo PC Serial PortGND1K1K1K1K1K5.6K5.6K1K1K5.6KRS-232 Level Shifter Figure 21: Sketch Map for RS-232 Interface Match Please visit vendor web site to select suitable IC, such as: http://www.maximintegrated.com and http://www.exar.com/. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 40 / 80 3.8. Audio Interfaces The module provides one analog input channels and two analog output channels. Table 9: Pin Definition of Audio Interface AIN can be used for input of microphone and line. An electret microphone is usually used. AIN are differential input channels. AOUT1 is used for output of the receiver. This channel is typically used for a receiver built into a handset. AOUT1 channel is a differential channel. AOUT2 is typically used with earphone. It is a single-ended and mono channel. SPK2P and AGND can establish a pseudo differential mode. All of these two audio channels support voice and ringtone output, and so on, and can be switched by AT+QAUDCH command. For more details, please refer to the document [1]. Use AT command AT+QAUDCH to select audio channel:  0--AIN/AOUT1, the default value is 0.  1--AIN/AOUT2, this channel is always used for earphone. For each channel, you can use AT+QMIC to adjust the input gain level of microphone. You can also use AT+CLVL to adjust the output gain level of receiver and speaker. AT+QSIDET is used to set the side-tone gain level. For more details, please refer to the document [1]. Interface Pin Name Pin No. Description AIN/AOUT1 MICP 3 Microphone positive input MICN 4 Microphone negative input SPK1P 5 Channel 1 Audio positive output SPK1N 6 Channel 1 Audio negative output AIN/AOUT2 MICP 3 Microphone positive input MICN 4 Microphone negative input SPK2P 2 Channel 2 Audio positive output AGND 1 Form a pseudo-differential pair with SPK2P
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 41 / 80 3.8.1. Decrease TDD Noise and other Noise The 33pF capacitor is applied for filtering out 900MHz RF interference when the module is transmitting at EGSM900MHz. Without placing this capacitor, TDD noise could be heard. Moreover, the 10pF capacitor here is for filtering out 1800MHz RF interference. However, the resonant frequency point of a capacitor largely depends on the material and production technique. Therefore, customer would have to discuss with its capacitor vendor to choose the most suitable capacitor for filtering out GSM850MHz, EGSM900MHz, DCS1800MHz and PCS1900MHz separately. The severity degree of the RF interference in the voice channel during GSM transmitting period largely depends on the application design. In some cases, EGSM900 TDD noise is more severe; while in other cases, DCS1800 TDD noise is more obvious. Therefore, you can have a choice based on test results. Sometimes, even no RF filtering capacitor is required. The capacitor which is used for filtering out RF noise should be close to audio interface or other audio interfaces. Audio alignment should be as short as possible. In order to decrease radio or other signal interference, the position of RF antenna should be kept away from audio interface and audio alignment. Power alignment and audio alignment should not be parallel, and power alignment should be far away from audio alignment. The differential audio traces have to be placed according to the differential signal layout rule. 3.8.2. Microphone Interfaces Design AIN channel come with internal bias supply for external electret microphone. A reference circuit is shown in the following figure. MICPDifferential layoutModule10pF 33pF33pF33pFGNDGNDElectret MicrophoneGNDGND10pF10pFGNDGNDESDESDClose to ModuleMICNGNDGNDClose to Microphone06030603060306030603060333pF060333pF060333pF060310pF060310pF060310pF0603 Figure 22: Reference Design for AIN
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 42 / 80 3.8.3. Receiver and Speaker Interface Design SPK1PSPK1NDifferential layoutModule10pF 0603Close to speakerGNDESD 33pF 060333pF 0603GND10pF 0603 ESD 10pF 060333pF 0603 Figure 23: Handset Interface Design for AOUT1 SPK1PSPK1NDifferential layout AmplifiercircuitModule10pF 0603Close to speakerGNDESD 33pF 060333pF 0603GND10pF 0603 ESD 10pF 060333pF 0603 Figure 24: Speaker Interface Design with an Amplifier for AOUT1
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 43 / 80 SPK2PAGNDDifferential layout 10pF060333pF0603Close to SpeakerGNDESD Module22uF Figure 25: Handset Interface Design for AOUT2 ModuleSPK2PAGNDDifferential layout Amplifiercircuit10pF060310pF060333pF060333pF0603Close to SpeakerGNDGNDESD ESD C2C1 Figure 26: Speaker Interface Design with an Amplifier for AOUT2 The suitable differential audio amplifier can be chosen from the Texas Instrument’s website (http://www.ti.com/). There are also other excellent audio amplifier vendors in the market. 1. The value of C1 and C2 here depends on the input impedance of audio amplifier. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 44 / 80 3.8.4. Earphone Interface Design 1243MICP22uF33pFGNDAGNDClose to SocketAGND33pF10pFGNDAGNDModule 4.7uFSPK2PClose to ModuleGND33pF33pFDifferential layout33pFMICN 060306030603 060306030603060310pFGND10pF06030603060310pF10pF Figure 27: Earphone Interface Design 3.8.5. Audio Characteristics Table 10: Typical Electret Microphone Characteristics Table 11: Typical Speaker Characteristics Parameter Min. Typ. Max. Unit Working Voltage 1.2 1.5 2.0 V Working Current 200 500 uA External Microphone Load Resistance 2.2 K Ohm Parameter Min. Typ. Max. Unit AOUT1 Output Single-ended Load resistance 32 Ohm Ref level 0 2.4 Vpp Differential Load resistance 32 Ohm Ref level 0 4.8 Vpp
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 45 / 80 3.9. PCM Interface M26 supports PCM interface. It is used for digital audio transmission between the module and the device. This interface is composed of PCM_CLK, PCM_SYNC, PCM_IN and PCM_OUT signal lines. Pulse-code modulation (PCM) is a converter that changes the consecutive analog audio signal to discrete digital signal. The whole procedure of Pulse-code modulation contains sampling, quantizing and encoding. Table 12: Pin Definition of PCM Interface 3.9.1. Configuration M26 module supports 13-bit line code PCM format. The sample rate is 8 KHz, and the clock source is 256 KHz, and the module can only act as master mode. The PCM interface supports both long and short synchronization simultaneously. Furthermore, it only supports MSB first. For detailed information, please refer to the table below. Table 13: Configuration AOUT2 Output Single-ended Load resistance 32 Load Resistance Reference level 0 2.4 Vpp Pin Name Pin No. Description PCM_CLK 30 PCM clock output PCM_SYNC 31 PCM frame synchronization output PCM_IN 32 PCM data input PCM_OUT 33 PCM data output PCM Line Interface Format Linear Data Length Linear: 13 bits
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 46 / 80 3.9.2. Timing The sample rate of the PCM interface is 8 KHz and the clock source is 256 KHz, so every frame contains 32 bits data, since M26 supports 16 bits line code PCM format, the left 16 bits are invalid. The following diagram shows the timing of different combinations. The synchronization length in long synchronization format can be programmed by firmware from one bit to eight bits. In the Sign extension mode, the high three bits of 16 bits are sign extension, and in the Zero padding mode, the low three bits of 16 bits are zero padding. Under zero padding mode, you can configure the PCM input and output volume by executing AT+QPCMVOL command. For more details, please refer to Chapter 3.9.4. 12 11 10 9 8 7 6 5 4 3 2 1 012 11 10 9 8 7 6 5 4 3 2 1 0PCM_CLKPCM_SYNCPCM_OUTPCM_INMSBMSBSign extensionSign extension Figure 28: Long Synchronization & Sign Extension Diagram Sample Rate 8KHz PCM Clock/Synchronization Source PCM master mode: clock and synchronization is generated by module PCM Synchronization Rate 8KHz PCM Clock Rate PCM master mode: 256 KHz (line) PCM Synchronization Format Long/short synchronization PCM Data Ordering MSB first Zero Padding Yes Sign Extension Yes
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 47 / 80 12 11 10 9 8 7 6 5 4 3 2 1 012 11 10 9 8 7 6 5 4 3 2 1 0PCM_CLKPCM_SYNCPCM_OUTPCM_INMSBMSBZero paddingZero padding Figure 29: Long Synchronization & Zero Padding Diagram PCM_CLKPCM_SYNCPCM_OUTPCM_IN12 11 10 9 8 7 6 5 4 3 2 1 012 11 10 9 8 7 6 5 4 3 2 1 0MSBMSBSign extensionSign extension Figure 30: Short Synchronization & Sign Extension Diagram PCM_CLKPCM_SYNCPCM_OUTPCM_IN12 11 10 9 8 7 6 5 4 3 2 1 012 11 10 9 8 7 6 5 4 3 2 1 0MSBMSBZero paddingZero padding Figure 31: Short Synchronization & Zero Padding Diagram
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 48 / 80 3.9.3. Reference Design M26 can only work as a master, providing synchronization and clock source. The reference design is shown as below. PCM_SYNCPCM_CLKPCM_OUTPCM_INPCM_SYNCPCM_CLKPCM_INPCM_OUTModule(Master)Peripheral(Slave) Figure 32: Reference Design for PCM 3.9.4. AT Command There are two AT commands about the configuration of PCM, listed as below. AT+QPCMON can configure operating mode of PCM. AT+QPCMON=mode, Sync_Type, Sync_Length, SignExtension, MSBFirst Table 14: QPCMON Command Description Parameter Scope Description Mode 0~2 0: Close PCM 1: Open PCM 2: Open PCM when audio talk is set up Sync_Type 0~1 0: Short synchronization 1: Long synchronization Sync_Length 1~8 Programmed from one bit to eight bit SignExtension 0~1 0: Zero padding 1: Sign extension MSBFirst 0~1 0: MSB first 1: Not support
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 49 / 80 AT+QPCMVOL can configure the volume of input and output. AT+QPCMVOL=vol_pcm_in, vol_pcm_out Table 15: QPCMVOL Command Description 3.10. SIM Card Interface The SIM interface supports the functionality of the GSM Phase 1 specification and also supports the functionality of the new GSM Phase 2+ specification for FAST 64 kbps SIM card, which is intended for use with a SIM application Tool-kit. The SIM interface is powered by an internal regulator in the module. Both 1.8V and 3.0V SIM Cards are supported. Table 16: Pin Definition of the SIM Interface Parameter Scope Description vol_pcm_in 0~32767 Set the input volume vol_pcm_out 0~32767 Set the output volume The voice may be distorted when this value exceeds 16384. Pin Name Pin No. Description SIM_VDD 14 Supply power for SIM card. Automatic detection of SIM card voltage. 3.0V±5% and 1.8V±5%. Maximum supply current is around 10mA. SIM_CLK 13 SIM card clock. SIM_DATA 11 SIM card data I/O. SIM_RST 12 SIM card reset. SIM_GND 10 SIM card ground.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 50 / 80 The reference circuit for a 6-pin SIM card socket is illustrated as the following figure. ModuleSIM_VDDSIM_GNDSIM_RSTSIM_CLKSIM_DATA 22R22R22R100nF SIM_HolderGNDTVS33pF33pF 33pFVCCRSTCLK IOVPPGNDGND33pF Figure 33: Reference Circuit for SIM Interface with the 6-pin SIM Card Holder For more information of SIM card holder, you can visit http://www.amphenol.com and http://www.molex.com . In order to enhance the reliability and availability of the SIM card in application. Please follow the below criteria in the SIM circuit design:  Keep layout of SIM card as close as possible to the module. Assure the possibility of the length of the trace is less than 200mm.  Keep SIM card signal away from RF and VBAT alignment.  Assure the ground between module and SIM cassette short and wide. Keep the width of ground no less than 0.5mm to maintain the same electric potential. The decouple capacitor of SIM_VDD is less than 1uF and must be near to SIM cassette.  To avoid cross talk between SIM_DATA and SIM_CLK. Keep them away with each other and shield them with surrounded ground.  In order to offer good ESD protection, it is recommended to add a TVS diode array. For more information of TVS diode, please visit http://www.onsemi.com/. The most important rule is to place the ESD protection device close to the SIM card socket and make sure the nets being protected will go through the ESD device first and then lead to module. The 22Ω resistors should be connected in series between the module and the SIM card so as to suppress the EMI spurious transmission and enhance the ESD protection. Please to be noted that the SIM peripheral circuit should be close to the SIM card socket.  Place the RF bypass capacitors (33pF) close to the SIM card on all signals line for improving EMI.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 51 / 80 3.11. ADC The module provides an ADC channel to measure the value of voltage. Please give priority to the use of ADC0 channel. The command AT+QADC can read the voltage value applied on ADC0 pin. For details of this AT command, please refer to the document [1]. In order to improve the accuracy of ADC, the layout of ADC should be surrounded by ground. Table 17: Pin Definition of the ADC Table 18: Characteristics of the ADC 3.12. Behaviors of The RI Table 19: Behaviors of the RI Pin Name Pin No. Description AVDD 8 Reference voltage of ADC circuit ADC0 9 Analog to digital converter. Item Min. Typ. Max. Units Voltage Range 0 2.8 V ADC Resolution 10 bits ADC Accuracy 2.7 mV State RI Response Standby HIGH Voicecall Change to LOW, then: 1. Change to HIGH when call is established. 2. Use ATH to hang up the call, RI changes to HIGH. 3. Calling part hangs up, RI changes to HIGH first, and changes to LOW for 120ms indicating ―NO CARRIER‖ as an URC, then changes to HIGH again. 4. Change to HIGH when SMS is received. SMS When a new SMS comes, the RI changes to LOW and holds low level for about
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 52 / 80 If the module is used as a caller, the RI would maintain high except the URC or SMS is received. On the other hand, when it is used as a receiver, the timing of the RI is shown below. RIIdle RingOff-hook by “ATA”On-hook by “ATH”HIGHLOW SMS received Figure 34: RI Behavior of Voice Calling as a Receiver RIIdle Calling On-hookTalkingHIGHLOWIdle Figure 35: RI Behavior as a Caller RIIdle or Talking URC or SMS received HIGHLOW120ms Figure 36: RI Behavior of URC or SMS Received 120ms, then changes to HIGH. URC Certain URCs can trigger 120ms low level on RI. For more details, please refer to the document [1]
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 53 / 80 3.13. Network Status Indication The NETLIGHT signal can be used to drive a network status indicator LED. The working state of this pin is listed in the following table. Table 20: Working State of the NETLIGHT A reference circuit is shown as below. ModuleNETLIGHT 4.7K47K300RVBAT Figure 37: Reference Design for NETLIGHT State Module Function Off The module is not running. 64ms On/800ms Off The module is not synchronized with network. 64ms On/2000ms Off The module is synchronized with network. 64ms On/600ms Off The GPRS data transmission after dialing the PPP connection.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 54 / 80 3.14. RF Transmitting Signal Indication The M26 provides a RFTXMON pins which will rise when the transmitter is active and fall after the transmitter activity is completed. Table 21: Pin Definition of the RFTXMON There are two different modes for this function: 1) Active during the TX activity RFTXMON pin is used to indicate the TX burst, when it outputs a high level, 220us later there will be a TX burst. You can execute AT+QCFG=“RFTXburst”, 1 to enable the function. The timing of the RFTXMON signal is shown below. Transmit burstRFTXMON577us220us 220us 577us4.615ms Figure 38: RFTXMON Signal during Burst Transmission Pin Name Pin No. Description RFTXMON 25 Transmission signal indication
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 55 / 80 2) Active during the Call RFTXMON will be HIGH during a call and the pin will become LOW after being hanged up. You can execute AT+QCFG=“RFTXburst”, 2 to enable the function. The timing of the RFTXMON signal is shown below. RFTXMONIdle Calling Hanged upHIGHLOW Figure 39: RFTXMON Signal during Call
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 56 / 80 4 Antenna Interface M26 has two antenna interfaces, GSM antenna and BT antenna. The Pin 26 is the Bluetooth antenna pad. The Pin 35 is the GSM antenna pad. The RF interface of the two antenna pad has an impedance of 50Ω. 4.1. GSM Antenna Interface There is a GSM antenna pad named RF_ANT for M26. Table 22: Pin Definition of the RF_ANT 4.1.1. Reference Design The external antenna must be matched properly to achieve best performance, so the matching circuit is necessary, the reference design for RF is shown as below. ModuleRF_ANT0RNM NM Figure 40: Reference Design for GSM Antenna Pin Name Pin No. Description GND 34 Ground RF_ANT 35 GSM antenna pad GND 36 Ground GND 37 Ground
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 57 / 80 M26 provides an RF antenna pad for antenna connection. The RF trace in host PCB connected to the module RF antenna pad should be coplanar waveguide line or microstrip line, whose characteristic impedance should be close to 50Ω. M26 comes with grounding pads which are next to the antenna pad in order to give a better grounding. Besides, a π type match circuit is suggested to be used to adjust the RF performance. To minimize the loss on the RF trace and RF cable, take design into account carefully. The following table shows the requirement on GSM antenna. Table 23: Antenna Cable Requirements Type Requirements GSM850/EGSM900 Cable insertion loss <1dB DCS1800/PCS1900 Cable insertion loss <1.5dB Table 24: Antenna Requirements Type Requirements Frequency Range Depending by frequency band (s) provided by the network operator VSWR ≤ 2 Gain (dBi) 1 Max Input Power (W) 50 Input Impedance (Ω) 50 Polarization Type Vertical 4.1.2. RF Output Power Table 25: The Module Conducted RF Output Power Frequency Max. Min. GSM850 33dBm±2dB 5dBm±5dB EGSM900 33dBm±2dB 5dBm±5dB DCS1800 30dBm±2dB 0dBm±5dB
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 58 / 80 In GPRS 4 slots TX mode, the max output power is reduced by 2.5dB. This design conforms to the GSM specification as described in section 13.16 of 3GPP TS 51.010-1. 4.1.3. RF Receiving Sensitivity Table 26: The Module Conducted RF Receiving Sensitivity 4.1.4. Operating Frequencies Table 27: The Module Operating Frequencies PCS1900 30dBm±2dB 0dBm±5dB Frequency Receive Sensitivity GSM850 < -109dBm EGSM900 < -109dBm DCS1800 < -109dBm PCS1900 < -109dBm Frequency Receive Transmit ARFCH GSM850 869~894MHz 824~849MHz 128~251 EGSM900 925~960MHz 880~915MHz 0~124, 975~1023 DCS1800 1805~1880MHz 1710~1785MHz 512~885 PCS1900 1930~1990MHz 1850~1910MHz 512~810 NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 59 / 80 4.1.5. RF Cable Soldering Soldering the RF cable to RF pad of module correctly will reduce the loss on the path of RF, please refer to the following example of RF soldering. Figure 41: RF Soldering Sample 4.2. Bluetooth Antenna Interface M26 supports Bluetooth interface. Bluetooth is a wireless technology that allows devices to communicate, or transmit data or voice, wirelessly over a short distance. It is described as a short-range communication technology intended to replace the cables connecting portable and/or fixed devices while maintaining high level of security. Bluetooth is standardized as IEEE802.15 and operates in the 2.4 GHz range using RF technology. Its data rates of up to 3Mbps. M26 is fully compliant with Bluetooth specification 3.0. M26 supports profile including SPP and OPP. The module provides a Bluetooth antenna pad named BT_ANT. Table 28: Pin Definition of the BT_ANT Pin Name Pin No. Description BT_ANT 26 BT antenna pad GND 27 Ground
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 60 / 80 The external antenna must be matched properly to achieve best performance, so the matching circuit is necessary, the connection is recommended as in the following figure: ModuleBT_ANT0RNM NM Figure 42: Reference Design for Bluetooth Antenna There are some suggestions for placing components and RF trace lying for Bluetooth RF traces:  Antenna matching circuit should be closed to the antenna;  Keep the RF traces as 50Ω;  The RF traces should be kept far away from the high frequency signals and strong disturbing source.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 61 / 80 5 Electrical, Reliability and Radio Characteristics 5.1. Absolute Maximum Ratings Absolute maximum ratings for power supply and voltage on digital and analog pins of module are listed in the following table: Table 29: Absolute Maximum Ratings 5.2. Operating Temperature The operating temperature is listed in the following table: Table 30: Operating Temperature Parameter Min. Max. Unit VBAT -0.3 +4.73 V Peak Current of Power Supply 0 2 A RMS Current of Power Supply (during one TDMA- frame) 0 0.7 A Voltage at Digital Pins -0.3 3.08 V Voltage at Analog Pins -0.3 3.08 V Voltage at Digital/analog Pins in Power Down Mode -0.25 0.25 V Parameter Min. Typ. Max. Unit Normal Temperature -35 +25 +80 ℃
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 62 / 80 1) When the module works within this temperature range, the deviation from the GSM specification may occur. For example, the frequency error or the phase error will be increased. 5.3. Power Supply Ratings Table 31: The Module Power Supply Ratings Restricted Operation1) -40 ~ -35 +80 ~ +85 ℃ Storage Temperature -45 +90 ℃ Parameter Description Conditions Min. Typ. Max. Unit VBAT Supply voltage Voltage must stay within the min/max values, including voltage drop, ripple, and spikes. 3.3 4.0 4.6 V Voltage drop during transmitting burst Maximum power control level on GSM850 and EGSM900. 400 mV IVBAT Average supply current Power down mode SLEEP mode @DRX=5 150 1.3 uA mA Minimum functionality mode AT+CFUN=0 IDLE mode SLEEP mode AT+CFUN=4 IDLE mode SLEEP mode 13 0.98 13 1.0 mA mA mA mA TALK mode GSM850/EGSM9001) DCS1800/PCS19002) 223/219 153/151 mA mA DATA mode, GPRS (3Rx, 2Tx) GSM850/EGSM9001) DCS1800/PCS19002) 363/393 268/257 mA mA DATA mode, GPRS (2 Rx, 3Tx) GSM850/EGSM9001) DCS1800/PCS19002) 506/546 366/349 mA mA NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 63 / 80 1. 1) Power control level PCL 5. 2. 2) Power control level PCL 0. 3. 3) Under the GSM850 and EGSM900 spectrum, the power of 1Rx and 4Tx has been reduced. 5.4. Current Consumption The values of current consumption are shown as below. Table 32: The Module Current Consumption DATA mode, GPRS (4 Rx, 1Tx) GSM850/EGSM9001) DCS1800/PCS19002) 217/234 172/170 mA mA DATA mode, GPRS (1Rx, 4Tx) GSM850/EGSM9001) DCS1800/PCS19002) 458/4853) 462/439 mA mA Peak supply current (during transmission slot) Maximum power control level on GSM850 and EGSM900. 1.6 2 A Condition Current Consumption Voice Call GSM850 @power level #5 <300mA, Typical 223mA @power level #12, Typical 83mA @power level #19, Typical 62mA EGSM900 @power level #5 <300mA, Typical 219mA @power level #12, Typical 83mA @power level #19, Typical 63mA DCS1800 @power level #0 <250mA, Typical 153mA @power level #7, Typical 73mA @power level #15, Typical 60mA PCS1900 @power level #0 <250mA, Typical 151mA @power level #7, Typical 76mA @power level #15, Typical 61mA GPRS Data NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 64 / 80 DATA Mode, GPRS ( 3 Rx, 2Tx ) CLASS 12 GSM850 @power level #5 <550mA, Typical 363mA @power level #12, Typical 131mA @power level #19, Typical 91mA EGSM900 @power level #5 <550mA, Typical 393mA @power level #12, Typical 132mA @power level #19, Typical 92mA DCS1800 @power level #0 <450mA, Typical 268mA @power level #7, Typical 112mA @power level #15, Typical 88mA PCS1900 @power level #0 <450mA, Typical 257mA @power level #7, Typical 119mA @power level #15, Typical 89mA DATA Mode, GPRS ( 2 Rx, 3Tx ) CLASS 12 GSM850 @power level #5 <640mA, Typical 506mA @power level #12, Typical 159mA @power level #19, Typical 99mA EGSM900 @power level #5 <600mA, Typical 546mA @power level #12, Typical 160mA @power level #19, Typical 101mA DCS1800 @power level #0 <490mA, Typical 366mA @power level #7, Typical 131mA @power level #15, Typical 93mA PCS1900 @power level #0 <480mA, Typical 348mA @power level #7, Typical 138mA @power level #15, Typical 94mA DATA Mode, GPRS ( 4 Rx,1Tx ) CLASS 12 GSM850 @power level #5 <350mA, Typical 216mA @power level #12, Typical 103mA @power level #19, Typical 83mA EGSM900 @power level #5 <350mA, Typical 233mA @power level #12, Typical 104mA @power level #19, Typical 84mA DCS1800 @power level #0 <300mA, Typical 171mA @power level #7, Typical 96mA @power level #15, Typical 82mA PCS1900 @power level #0 <300mA, Typical 169mA @power level #7, Typical 98mA @power level #15, Typical 83mA DATA Mode, GPRS ( 1 Rx, 4Tx ) CLASS 12
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 65 / 80 GPRS Class 12 is the default setting. The module can be configured from GPRS Class 1 to Class 12. Setting to lower GPRS class would make it easier to design the power supply for the module. 5.5. Electro-static Discharge Although the GSM engine is generally protected against Electro-static Discharge (ESD), ESD protection precautions should still be emphasized. Proper ESD handling and packaging procedures must be applied throughout the processing, handling and operation of any applications using the module. The measured ESD values of module are shown as the following table: Table 33: The ESD Endurance (Temperature: 25ºC , Humidity: 45%) GSM850 @power level #5 <660mA, Typical 457mA @power level #12, Typical 182mA @power level #19, Typical 106mA EGSM900 @power level #5 <660mA, Typical 484mA @power level #12, Typical 187mA @power level #19, Typical 109mA DCS1800 @power level #0 <530mA, Typical 461mA @power level #7, Typical 149mA @power level #15, Typical 97mA PCS1900 @power level #0 <530mA, Typical 439mA @power level #7, Typical 159mA @power level #15, Typical 99mA Tested Point Contact Discharge Air Discharge VBAT, GND ±5KV ±10KV RF_ANT ±5KV ±10KV TXD, RXD ±2KV ±4KV Others ±0.5KV ±1KV NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 66 / 80 6 Mechanical Dimensions This chapter describes the mechanical dimensions of the module. 6.1. Mechanical Dimensions of Module Figure 43: M26 Module Top and Side Dimensions (Unit: mm)
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 67 / 80 Figure 44: M26 Module Bottom Dimensions (Unit: mm)
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 68 / 80 6.2. Recommended Footprint 1142336 Figure 45: Recommended Footprint (Unit: mm) 1. The module should be kept about 3mm away from other components in the host PCB. 2. The circular test points with a radius of 1.75mm in the above recommended footprint should be treated as keepout areas. (―keepout‖ means do not pour copper on the mother board). NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 69 / 80 6.3. Top View of the Module Figure 46: Top View of the Module 6.4. Bottom View of the Module Figure 47: Bottom View of the Module
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 70 / 80 7 Storage and Manufacturing 7.1. Storage M26 module is distributed in a vacuum-sealed bag. The restriction for storage is shown as below. Shelf life in the vacuum-sealed bag: 12 months at environments of <40ºC temperature and <90%RH. After the vacuum-sealed bag is opened, devices that need to be mounted directly must be:  Mounted within 72 hours at the factory environment of ≤30ºC temperature and <60% RH.  Stored at <10% RH. Devices require baking before mounting, if any circumstance below occurs.  When the ambient temperature is 23ºC ±5 ºC , humidity indication card shows the humidity is >10% before opening the vacuum-sealed bag.  If ambient temperature is <30ºC and the humidity is <60%, the devices have not been mounted during 72hours.  Stored at >10% RH. If baking is required, devices should be baked for 48 hours at 125ºC ±5 ºC . As plastic container cannot be subjected to high temperature, devices must be removed prior to high temperature (125ºC ) bake. If shorter bake times are desired, refer to the IPC/JEDECJ-STD-033 for bake procedure. NOTE
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 71 / 80 7.2. Soldering The squeegee should push the paste on the surface of the stencil that makes the paste fill the stencil openings and penetrate to the PCB. The force on the squeegee should be adjusted so as to produce a clean stencil surface on a single pass. To ensure the module soldering quality, the thickness of stencil at the hole of the module pads should be 0.2 mm for M26.For more details, please refer to document [12] It is suggested that peak reflow temperature is from 235ºC to 245ºC (for SnAg3.0Cu0.5 alloy). Absolute max reflow temperature is 260ºC. To avoid damage to the module when it was repeatedly heated, it is suggested that the module should be mounted after the first panel has been reflowed. The following picture is the actual diagram which we have operated. Time(s)50 100 150 200 250 30050100150200250 160℃ 200℃217070s~120s40s~60sBetween 1~3℃/SPreheat Heating Cooling℃sLiquids Temperature Figure 48: Ramp-Soak-Spike Reflow Profile 7.3. Packaging The modules are stored in a vacuum-sealed bag which is ESD protected. It should not be opened until the devices are ready to be soldered onto the application.
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 72 / 80 7.3.1. Tape and Reel Packaging The reel is 330mm in diameter and each reel contains 250 modules. Figure 49: Tape and Reel Specification Figure 50: Dimensions of Reel
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 73 / 80 8 Appendix A Reference Table 34: Related Documents SN Document Name Remark [1] Quectel_M26_AT_Commands_Manual AT commands manual [2] ITU-T Draft new recommendation V.25ter Serial asynchronous automatic dialing and control [3] GSM 07.07 Digital cellular telecommunications (Phase 2+); AT command set for GSM Mobile Equipment (ME) [4] GSM 07.10 Support GSM 07.10 multiplexing protocol [5] GSM 07.05 Digital cellular telecommunications (Phase 2+); Use of Data Terminal Equipment – Data Circuit terminating Equipment (DTE – DCE) interface for Short Message Service (SMS) and Cell Broadcast Service (CBS) [6] GSM 11.14 Digital cellular telecommunications (Phase 2+); Specification of the SIM Application Toolkit for the Subscriber Identity module – Mobile Equipment (SIM – ME) interface [7] GSM 11.11 Digital cellular telecommunications (Phase 2+); Specification of the Subscriber Identity module – Mobile Equipment (SIM – ME) interface [8] GSM 03.38 Digital cellular telecommunications (Phase 2+); Alphabets and language-specific information [9] GSM 11.10 Digital cellular telecommunications (Phase 2); Mobile Station (MS) conformance specification; Part 1: Conformance specification
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 74 / 80 Table 35: Terms and Abbreviations [10] GSM_UART_Application_Note UART port application note [11] GSM_EVB_User_Guide GSM EVB user guide [12] Module_Secondary_SMT_User_Guide Module secondary SMT user guide [13] Quectel_GSM_Module_Digital_IO_Application_Note GSM Module Digital IO Application Note Abbreviation Description ADC Analog-to-Digital Converter AMR Adaptive Multi-Rate ARP Antenna Reference Point ASIC Application Specific Integrated Circuit BER Bit Error Rate BOM Bill of Material BT Bluetooth BTS Base Transceiver Station CHAP Challenge Handshake Authentication Protocol CS Coding Scheme CSD Circuit Switched Data CTS Clear to Send DAC Digital-to-Analog Converter DRX Discontinuous Reception DSP Digital Signal Processor DCE Data Communications Equipment (typically module) DTE Data Terminal Equipment (typically computer, external controller) DTR Data Terminal Ready
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 75 / 80 DTX Discontinuous Transmission EFR Enhanced Full Rate EGSM Enhanced GSM EMC Electromagnetic Compatibility ESD Electrostatic Discharge ETS European Telecommunication Standard FCC Federal Communications Commission (U.S.) FDMA Frequency Division Multiple Access FR Full Rate GMSK Gaussian Minimum Shift Keying GPRS General Packet Radio Service GSM Global System for Mobile Communications G.W Gross Weight HR Half Rate I/O Input/Output IC Integrated Circuit IMEI International Mobile Equipment Identity IOmax Maximum Output Load Current kbps Kilo Bits Per Second LED Light Emitting Diode Li-Ion Lithium-Ion MO Mobile Originated MOQ Minimum Order Quantity MP Manufacture Product MS Mobile Station (GSM engine)
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 76 / 80 MT Mobile Terminated N.W Net Weight PAP Password Authentication Protocol PBCCH Packet Switched Broadcast Control Channel PCB Printed Circuit Board PDU Protocol Data Unit PPP Point-to-Point Protocol RF Radio Frequency RMS Root Mean Square (value) RTC Real Time Clock RX Receive Direction SIM Subscriber Identification Module SMS Short Message Service TDMA Time Division Multiple Access TE Terminal Equipment TX Transmitting Direction UART Universal Asynchronous Receiver & Transmitter URC Unsolicited Result Code USSD Unstructured Supplementary Service Data VSWR Voltage Standing Wave Ratio VOmax Maximum Output Voltage Value VOnorm Normal Output Voltage Value VOmin Minimum Output Voltage Value VIHmax Maximum Input High Level Voltage Value VIHmin Minimum Input High Level Voltage Value
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 77 / 80 VILmax Maximum Input Low Level Voltage Value VILmin Minimum Input Low Level Voltage Value VImax Absolute Maximum Input Voltage Value VInorm Absolute Normal Input Voltage Value VImin Absolute Minimum Input Voltage Value VOHmax Maximum Output High Level Voltage Value VOHmin Minimum Output High Level Voltage Value VOLmax Maximum Output Low Level Voltage Value VOLmin Minimum Output Low Level Voltage Value Phonebook Abbreviations LD SIM Last Dialing phonebook (list of numbers most recently dialed) MC Mobile Equipment list of unanswered MT Calls (missed calls) ON SIM (or ME) Own Numbers (MSISDNs) list RC Mobile Equipment list of Received Calls SM SIM phonebook
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 78 / 80 9 Appendix B GPRS Coding Scheme Four coding schemes are used in GPRS protocol. The differences between them are shown in the following table. Table 36: Description of Different Coding Schemes Scheme Code Rate USF Pre-coded USF Radio Block excl.USF and BCS BCS Tail Coded Bits Punctured Bits Data Rate Kb/s CS-1 1/2 3 3 181 40 4 456 0 9.05 CS-2 2/3 3 6 268 16 4 588 132 13.4 CS-3 3/4 3 6 312 16 4 676 220 15.6 CS-4 1 3 12 428 16 - 456 - 21.4 Radio block structure of CS-1, CS-2 and CS-3 is shown as the figure below. Figure 51: Radio Block Structure of CS-1, CS-2 and CS-3 Rate 1/2 convolutional coding Puncturing 456 bits USF BCS Radio Block
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 79 / 80 Radio block structure of CS-4 is shown as the following figure. Figure 52: Radio Block Structure of CS-4 Block Code No coding 456 bits USF BCS Radio Block
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 80 / 80 10 Appendix C GPRS Multi-slot Class Twenty-nine classes of GPRS multi-slot modes are defined for MS in GPRS specification. Multi-slot classes are product dependant, and determine the maximum achievable data rates in both the uplink and downlink directions. Written as 3+1 or 2+2, the first number indicates the amount of downlink timeslots, while the second number indicates the amount of uplink timeslots. The active slots determine the total number of slots the GPRS device can use simultaneously for both uplink and downlink communications. The description of different multi-slot classes is shown in the following table. Table 37: GPRS Multi-slot Classes Multislot Class Downlink Slots Uplink Slots Active Slots 1 1 1 2 2 2 1 3 3 2 2 3 4 3 1 4 5 2 2 4 6 3 2 4 7 3 3 4 8 4 1 5 9 3 2 5 10 4 2 5 11 4 3 5 12 4 4 5
GSM/GPRS Module Series M26 Hardware Design M26_Hardware_Design Confidential / Released 81 / 81 11 FCC WarningAny Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment. This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. To satisfy FCC RF Exposure requirements for this transmission devices, a separation distance of 20cm or more should be maintained between the antenna of this device and persons during operation. To ensure compliance, operation at closer than this distance is not recommended. The antenna(s) used for this transmitter must not be co-located or operating in conjunction with any other antenna or transmitter. Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.The modular transmitter must be equipped with either a permanently affixed label or must be capable of electronically displaying its FCC identification number：(A) If using a permanently affixed label, the modular transmitter must be labeled with its own FCC identification number, and, if the FCC identification number is not visible when the module is installed inside another device, then the outside of the device into which the module is installed must also display a label referring to the enclosed module. This exterior label can use wording such as the following: “Contains Transmitter Module FCC ID:XMR201604M26.” Any similar wording that expresses the same meaning may be used. The Grantee may either provide such a label, an example of which must be included in the application for equipment authorization, or, must provide adequate instructions along with the module which explain this requirement. In the latter case, a copy of these instructions must be included in the application for equipment authorization.

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