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SimCom SIM900B Hardware Design

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SIM900B_Hardware Design_V2.01

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Summary of Contents for SimCom SIM900B

  • Page 1 SIM900B_Hardware Design_V2.01...
  • Page 2 Document Control ID General Notes SIMCom offers this information as a service to its customers, to support application and engineering efforts that use the products designed by SIMCom. The information provided is based upon requirements specifically provided to SIMCom by the customers. SIMCom has not undertaken any independent search for additional relevant information, including any information that may be in the customer’s possession.

  • Page 3: Table Of Contents

    Monitoring Power Supply ........................15 Power on/down Scenarios ........................15 3.3.1 Power on SIM900B..........................15 3.3.1.1 Turn on SIM900B Using the PWRKEY Pin (Power on) ..............15 3.3.2 Power down SIM900B........................16 3.3.2.1 Power down SIM900B by the PWRKEY Pin ..................17 3.3.2.2...
  • Page 4 Mounting SIM900B onto the application platform ................41 Board-to-board connector........................41 Mechanical dimensions of the RUNFENG BB530-06001-20R............. 42 RF connector ............................43 Top and Bottom View of the SIM900B ....................44 PIN Assignment of SIM900B......................... 45 Appendix ................................46 A. Related Documents............................46 B.
  • Page 5 TABLE 21: THE ESD CHARACTERISTICS (TEMPERATURE: 25℃, HUMIDITY: 45 %) ........36 TABLE 22: SIM900B GSM 900 AND GSM 850 CONDUCTED RF OUTPUT POWER..........37 TABLE 23: SIM900B DCS 1800 AND PCS 1900 CONDUCTED RF OUTPUT POWER ..........38 TABLE 24: SIM900B CONDUCTED RF RECEIVE SENSITIVITY................39 TABLE 25: SIM900B OPERATING FREQUENCIES....................
  • Page 6 FIGURE 7: POWERED ON/DOWN MODULE USING BUTTON ................16 FIGURE 8: TIMING OF POWER ON MODULE......................16 FIGURE 9: TIMING OF POWER DOWN SIM900B BY PWRKEY ................17 FIGURE 10: TIMING OF RESTART SIM900B......................18 FIGURE 11: RTC SUPPLY FROM CAPACITOR......................20 FIGURE 12: RTC SUPPLY FROM NON-CHARGEABLE BATTERY .................

  • Page 7: Version History

    Smart Machine Smart Decision Version History Date Version Description of change Author 2010-04-08 1.01 Origin Huangqiuju 2010-05-31 1.02 Modify voltage domain ， current consumption and Huangqiuju figure37 2010-06-23 1.03 §2.1, §3.3. §3.4 Modify the power supply range from 3.2V~4.8V to 3.1V~4.8V Huangqiuju §3.7, Modify the VRTC pin connection when RTC backup is not needed.

  • Page 8: Introduction

    This document describes SIM900B hardware interface in great detail. This document can help user to quickly understand SIM900B interface specifications, electrical and mechanical details. With the help of this document and other SIM900B application notes, user guide, users can use SIM900B to design various applications quickly.
  • Page 9 Real time clock Support RTC Size: 40mm * 33mm*3mm Physical characteristics Weight: 7g Firmware upgrade Firmware upgradeable by debug port. SIM900B does work at this temperature, but some radio frequency characteristics may deviate from the GSM specification. SIM900B_Hardware Design_V2.01 2012-05-07...

  • Page 10: Operating Modes

    CS-4 21.4kbps 42.8kbps 85.6kbps Operating Modes The table below summarizes the various operating modes of SIM900B. Table 3: Overview of operating modes Mode Function Module will automatically go into sleep mode if the conditions of sleep mode are enabling and there is no on air and no hardware interrupt (such as GSM/GPRS GPIO interrupt or data on serial port).

  • Page 11: Sim900B Functional Diagram

    Smart Machine Smart Decision SIM900B Functional Diagram The following figure shows a functional diagram of SIM900B: The GSM baseband engine Flash and SRAM The GSM radio frequency part The antenna interface The board-to-board interface The Other interfaces SIM900B Antenna connector...

  • Page 12: Application Interface

    Smart Machine Smart Decision 3 Application Interface Pin Description Table 4: Pin description Pin name Pin number Description Comment Power supply VBAT 1,2,3,4,5,6,7,8 Power supply It is recommended to VRTC Power supply for RTC connect with a battery or a capacitor (e.g. 4.7uF). VDD_EXT 2.8V output power supply If it is unused, keep open.
  • Page 13 Smart Machine Smart Decision DISP _CS DISP_RST Keypad interface / GPIOs GPIO1/KBC4 GPIO2/KBC3 GPIO3/KBC2 Defaults are as GPIO, they can be If these pins are GPIO4/KBC1 multiplexed as keypad unused ,keep open GPIO6/KBR3 GPIO7/KBR4 GPIO8/KBR2 GPIO9/KBR1 GPIO5/KBC0 Just can be used as GPIO GPIO, if these pins are GPIO10/KBR0...

  • Page 14: Power Supply

    Power Supply The power supply range of SIM900B is from 3.2V to 4.8V. The transmitting burst will cause voltage drop and the power supply must be able to provide sufficient current up to 2A. For the VBAT input, a bypass capacitor (low ESR) such as a 100 µF is strongly recommended;...

  • Page 15: Minimizing Voltage Drop Of Vbat

    Turn on SIM900B Using the PWRKEY Pin (Power on) User can power on SIM900B by pulling down the PWRKEY pin for at least 1 second and release. This pin is already pulled up to 3V in the module internal, so external pull up is not necessary. Reference circuit is shown as below.

  • Page 16: Power Down Sim900B

    Serial Port Figure 8: Timing of power on module When power on procedure is completed, SIM900B will send following URC to indicate that the module is ready to operate at fixed baud rate. This URC does not appear when autobauding function is active.

  • Page 17: Power Down Sim900B By The Pwrkey Pin

    Power down SIM900B by the PWRKEY Pin User can power down SIM900B by pulling down the PWRKEY pin for at least 1 second and release. Please refer to the power on circuit. The power down scenario is illustrated in the following figure.

  • Page 18: Over-Temperature Or Under-Temperature Power Down

    Wait for at least 800mS after STATUS pin changed to low level. Power on the module. Delay > 800ms Restart Turn off PWRKEY （INPUT） Pull down the PWRKEY to turn on the module VDD_EXT （OUTPUT） Figure 10: Timing of restart SIM900B SIM900B_Hardware Design_V2.01 2012-05-07...

  • Page 19: Power Saving Mode

    Note: For SIM900B, it is requested to set AT command “AT+CSCLK=1” and to ensure DTR at high level to enable the sleep mode 1; the default value is 0, which can not make the module to go into sleep mode. For more details please refer to document [1].

  • Page 20: Sleep Mode 2 (At+Csclk=2)

    Note: For SIM900B, It is requested to set AT command “AT+CSCLK=2” to enable the sleep mode 2; the default value is 0, which can not make the module to enter sleep mode. For more details please refer to document [1].

  • Page 21: Serial Interfaces

    Figure 14: Seiko XH414H-IV01E Charge-Discharge Characteristic Serial Interfaces SIM900B provides two unbalanced asynchronous serial ports. One is the serial port and the other is the debug port. The module is designed as a DCE (Data Communication Equipment). The following figure shows the connection between module and client (DTE).

  • Page 22: Function Of Serial Port And Debug Port

    Smart Machine Smart Decision MODULE (DCE) CUSTOMER (DTE) Serial port Serial port1 RING Debug port Serial port2 DBG_TX DBG_RX Figure 15: Connection of the serial interfaces If only RXD and TXD are used in user’s application, other serial pins should be kept open. Please refer to following figure.

  • Page 23: Software Upgrade And Debug

    Smart Machine Smart Decision Autobauding allows SIM900B to automatically detect the baud rate of the host device. Pay more attention to the following requirements: Synchronization between DTE and DCE: When DCE powers on with autobauding enabled, user must firstly send character “A” to synchronize the baud rate.

  • Page 24: Speaker Interface Configuration

    Smart Machine Smart Decision AT command “AT+CMIC” is used to adjust the input gain level of microphone. AT command “AT+SIDET” is used to set the side-tone level. In addition, AT command “AT+CLVL” is used to adjust the output gain level. For more details, please refer to document [1] and document [5].

  • Page 25: Microphone Interfaces Configuration

    Smart Machine Smart Decision 3.7.2 Microphone Interfaces Configuration Figure 20: Microphone reference circuit 3.7.3 Earphone Interface Configuration Figure 21: Earphone reference circuit 3.7.4 Audio Electronic Characteristics SIM900B_Hardware Design_V2.01 2012-05-07...

  • Page 26: Sim Card Interface

    Smart Machine Smart Decision Table 6: Microphone Input Characteristics Parameter Unit Working Voltage Working Current External Microphone Load Resistance kΩ Internal biasing DC Characteristics Differential input <1% 15.9 mVrms voltage F=1KHz; pre-amp gain = 20 dB; PGA gain = 14 dB <5% mVrms F=1KHz;pre-amp...

  • Page 27: Design Considerations For Sim Card Holder

    Figure 23: Reference circuit of the 6-pin SIM card holder 3.8.2 Design Considerations for SIM Card Holder For 6-pin SIM card holder, SIMCom recommends to use Amphenol C707 10M006 5122. User can visit http://www.amphenol.com for more information about the holder.

  • Page 28: Table 8: Pin Description (Amphenol Sim Card Holder)

    SIM card reset SIM_CLK SIM card clock Connect to GND Not connect SIM_DATA SIM card data I/O For 8 pins SIM card holder, SIMCom recommends to use Molex 91228. User can visit http://www.molex.com more information about the holder. SIM900B_Hardware Design_V2.01 2012-05-07...

  • Page 29: Lcd Display/Spi Interface

    Detect SIM card presence LCD Display/SPI Interface SIM900B provides a serial LCD display interface. It could also be used as SPI interface in the embedded AT application. For details about embedded AT application, please refer to document [6]. Note: This function is not supported in the standard firmware. If user wants this function, the firmware must be customized.

  • Page 30: Adc

    Smart Machine Smart Decision 3.10 ADC SIM900B provides an auxiliary ADC, which can be used to measure the voltage. User can use AT command “AT+CADC” to read the voltage value. For details of this AT command, please refer to document [1].

  • Page 31: Network Status Indication

    Table 12: Status of the NETLIGHT pin Status SIM900B behavior SIM900B is not running 64ms On/ 800ms Off SIM900B not registered the network 64ms On/ 3000ms Off SIM900B registered to the network 64ms On/ 300ms Off GPRS communication is established A reference circuit is recommended in the following figure: SIM900B_Hardware Design_V2.01...

  • Page 32: General Purpose Input/Output (Gpio)

    Smart Machine Smart Decision Figure 30: Reference circuit of NETLIGHT 3.13 General Purpose Input/Output (GPIO) 3.14 Keypad Interface The keypad interface consists of 5 keypad column outputs and 4 keypad row inputs. The basic configuration is 5 keypad columns and 4 keypad rows, giving 20 keys. Table 13 : Pin definition of the keypad interface Name Function...

  • Page 33: Buzzer

    1. This function is not supported in the standard firmware. If user wants this function, the firmware must be customized. Please contact SIMCom for more details. 2. KBR0&KBC0 are used to power off the module, so user can’t connect these two pins as a key.

  • Page 34: Electrical, Reliability And Radio Characteristics

    4 Electrical, Reliability and Radio Characteristics Absolute Maximum Ratings The absolute maximum ratings stated in following table are stress ratings under non-operating conditions. Stresses beyond any of these limits will cause permanent damage to SIM900B. Table 14: Absolute maximum ratings Symbol...

  • Page 35: Sim_Vdd Characteristics

    Smart Machine Smart Decision Table 17: SIM card interface characteristics   Symbol Parameter Unit High-level input current Low-level input current High-level input voltage Low-level input voltage High-level output voltage Low-level output voltage SIM_VDD Characteristics Table 18: SIM_VDD characteristics   Symbol Parameter Unit 2.75...

  • Page 36: Electro-Static Discharge

    * In above table the current consumption value is the typical one of the module tested in laboratory. In the mass production stage, there may be differences among each individual. Electro-Static Discharge SIM900B is an ESD sensitive component, so more attention should be paid to the procedure of handling and packaging. The ESD test results are shown in the following table. ℃...

  • Page 37: Radio Characteristics

    The following table shows the module conducted output power, it is followed by the 3GPP TS 05.05 technical specification requirement. Table 22: SIM900B GSM 900 and GSM 850 conducted RF output power GSM 900 and EGSM 850 Tolerance (dB) for conditions...

  • Page 38: Module Rf Receive Sensitivity

    Smart Machine Smart Decision Table 23 : SIM900B DCS 1800 and PCS 1900 conducted RF output power DCS 1800 and PCS 1900 Tolerance (dB) for conditions Nominal output power (dBm) Normal Extreme ±2 ±2.5 ±3 ±4 ±3 ±4 ±3 ±4 ±3...

  • Page 39: Module Operating Frequencies

    Smart Machine Smart Decision Table 24 : SIM900B conducted RF receive sensitivity Frequency Receive sensitivity（Typical） Receive sensitivity(Max) GSM850 -109dBm -107dBm EGSM900 -109dBm -107dBm DCS1800 -109dBm -107dBm PCS1900 -109dBm -107dBm 4.9.3 Module Operating Frequencies The following table shows the module’s operating frequency range; it is followed by the 3GPP TS 05.05 technical specification requirement.

  • Page 40: Manufacturing

    This chapter describes the mechanical dimensions of SIM900B. Mechanical Dimensions of SIM900B Following figure shows the Mechanical dimensions of SIM900B (top view, side view and bottom view). Figure 32: Top an Side Mechanical dimensions of module （Unit: mm） SIM900B_Hardware Design_V2.01...

  • Page 41: Mounting Sim900B Onto The Application Platform

    Smart Machine Smart Decision Figure 33: Recommended PCB footprint outline（Unit: mm） Mounting SIM900B onto the application platform Use the connector BB530-06001-20R to fix the SIM900B onto the customer platform. Board-to-board connector SIMCom recommends to use RUNFENG Company’s BB530-06001-20R as the board-to-board connector. This high density SMT connector is designed for parallel PCB-to-PCB applications.

  • Page 42: Mechanical Dimensions Of The Runfeng Bb530-06001-20R

    Smart Machine Smart Decision Mechanical dimensions of the RUNFENG BB530-06001-20R Figure 34: BB530-06001-20R board-to-board connector   Figure 35 : Board-to-board connector physical photo   SIM900B_Hardware Design_V2.01 2012-05-07...

  • Page 43: Rf Connector

    To get good RF performance in user’s design, SIMCom suggests user to use the matching RF adapter cable which is also supplied by HRS (Part Number: U.FL-LP（V）-040), the following figure (Figure 41) is the dimensions of U.FL series RF adapter cable. User can contact SIMCom for more information.

  • Page 44: Top And Bottom View Of The Sim900B

    Smart Machine Smart Decision Figure 37: U.FL series RF adapter cable Top and Bottom View of the SIM900B Figure 38: Top view of the SIM900B Figure 39: Bottom view of the SIM900B SIM900B_Hardware Design_V2.01 2012-05-07...

  • Page 45: Pin Assignment Of Sim900B

    Smart Machine Smart Decision PIN Assignment of SIM900B Table 26 : PIN assignment PIN NO. PIN NAME PIN NO. PIN NAME VBAT VBAT VBAT VBAT VBAT VBAT VBAT VBAT VRTC SIM_PRESENCE VDD_EXT DISP_DATA SIM_VDD DISP_CLK SIM_DATA DISP_CS SIM_CLK DISP_D/C SIM_RST...

  • Page 46: Appendix

    Smart Machine Smart Decision Appendix A. Related Documents Table 27 : Related documents Document name Remark SIM900_AT Command SIM900 AT Command Manual Manual AN_SIM900_TCPIP TCP/IP Applications User Manual SIM900_Multiplexer User SIM900 Multiplexer User Manual Application Note Manual_Application Note AN_SIM900 SIM900 Series Update Tool User Guide Series_Update Tool_UGD AN_SIM900_AUDIO Applications Note About SIM900 Audio...

  • Page 47: Terms And Abbreviations

    Smart Machine Smart Decision B. Terms and Abbreviations Table 28 : Terms and Abbreviations Abbreviation Description Analog-to-Digital Converter Adaptive Multi-Rate Coding Scheme Circuit Switched Data Clear to Send Data Terminal Equipment (typically computer, terminal, printer) Data Terminal Ready Discontinuous Transmission Enhanced Full Rate EGSM Enhanced GSM...

  • Page 48: Safety Caution

    Smart Machine Smart Decision Unsolicited Result Code USSD Unstructured Supplementary Service Data Phonebook abbreviations SIM fix dialing phonebook SIM last dialing phonebook (list of numbers most recently dialed) Mobile Equipment list of unanswered MT calls (missed calls) SIM (or ME) own numbers (MSISDNs) list Mobile Equipment list of received calls SIM phonebook Not connect...
  • Page 49 Smart Machine Smart Decision Contact us: Shanghai SIMCom Wireless Solutions Ltd. Add: SIM Technology Building,No.633,Jinzhong Road,Changning District,Shanghai P.R. China 200335 Tel: +86 21 3235 3300 Fax: +86 21 3235 3301 URL: www.sim.com/wm SIM900B_Hardware Design_V2.01 2012-05-07...

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