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This is a A7 GPRS/GSM/GPS Shield, which is use the newest A7 GSM/GPRS/GPS module, A7 module is a GSM/GPRS/GPS function module. It supports GSM/GPRS Quad-Band(850/900/1800/1900) network. Also, it supports voice calls, SMS messages, GPRS data service and GPS function. We can use it make a simple phone.
The module is controlled by AT command via UART and supports 3.3V and 4.2V logical level.

Model: ACS33042S
A7 001.jpg


  • Operating temperature -30 ℃ to + 80 ℃;
  • 1KG peak suction
  • Low standby current
  • Operating Voltage 3.3V-4.2V;
  • Power voltage> 3.4V;
  • Standby average current 3ma less;
  • Support the GSM / GPRS four bands, including 850,900,1800,1900MHZ;
  • Support China Mobile and China Unicom's 2G GSM network worldwide;
  • GPRS Class 10;
  • Sensitivity <-105;
  • Support voice calls;
  • Support SMS text messaging;
  • Support GPRS data traffic, the maximum data rate, download 85.6Kbps, upload 42.8Kbps;
  • Supports standard GSM07.07,07.05 AT commands and extended commands Ai-Thinker;
  • Supports two serial ports, a serial port to download an AT command port;
  • AT command supports the standard AT and TCP / IP command interface;
  • Support digital audio and analog audio support for HR, FR, EFR, AMR speech coding;
  • Support ROHS, FCC, CE, CTA certification;
  • SMT 42PIN


  • Make sure your SIM card is unlocked.
  • The product is provided as is without an insulating enclosure. Please observe ESD precautions specially in dry (low humidity) weather.
  • It just supports baud rate 115200bps.

A7 002.jpg Ea7e.jpg

Power supply - Vin connected to external 5~9VDC power supply
Antenna interface - connected to external antenna
Serial port select - select either software serial port or hareware serial port to be connected to GSM/GPRS Shield
Hardware Serial - D0/D1 of Arduino/Crowduino
Software serial - D7/D8 of Arduino/Crowduino
UART of A7 - UART pins breakout of A7
Microphone - to answer the phone call
Speaker - to answer the phone call
GPIO,PWM and ADC of A^ - GPIO,PWM and ADC pins breakout of SIM808
Power key - power up for A7 OFF key - power down for A7

Pins usage on Arduino

D0 - Unused if you select hardware serial port to communicate with GPRS+GSM+GPS Shield
D1 - Unused if you select hardware serial port to communicate with GPRS+GSM+GPS Shield
D2 - Unused
D3 - Unused
D4 - Unused
D5 - Unused
D6 - Unused
D7 - Used if you select software serial port to communicate with GPRS+GSM+GPS Shield
D8 - Used if you select software serial port to communicate with GPRS+GSM+GPS Shield
D9 - Used for software control the power up or down of the SIM808
D10 - Unused
D11 - Unused
D12 - Unused
D13 - Unused
D14(A0) - Unused
D15(A1) - Unused
D16(A2) - Unused
D17(A3) - Unused
D18(A4) - Unused
D19(A5) - Unused


Hardware installation

1.Insert an Micro SIM card to SIM Card Holder

6 Pin Holder for SIM Cards. Both 1.8 volts and 3.0 volts SIM Cards are supported by A6 GPRS/GSM Shield, the SIM card voltage type is automatically detected.
A7 004.jpg

2.Connect the Antenna

A miniature coaxial RF connector is present on the A6 GPRS/GSM Shield board to connect with a GSM Antenna. The connector present on the A6 GPRS/GSM Shield is called a U.FL connecto.The GSM Antenna supplied with the GPRS Shield has an SMA connector (and not an RP-SMA connector) on it.The connection topology is shown in the diagram below:

A7 0005.jpg

3.Plug to Arduino/Crowduino

The A7 GPRS/GSM Shield, like any other well designed shield, is stackable as shown in the photo below.And connect Arduino to PC by using a USB cable.

A7 Shield correct connection.jpg

With serial debugging tools

1.Before use the serial debugging tool, we need select the hareware serial port.
Male - Female Splittable Jumper Wire Connect the A7_RXD to MTXD and A7_TXD to MRXD with female-feamale splittable jumper wire.

A7 0008.jpg

2.Download the serial debugging tool,unzip it and open the sscom32E.exe file.

A7 0010.jpg

click the "EXT":

A7 009.jpg

3.Let's start the mudule,Long press the power key for more than 2 seconds,if you will see some information in the serial debug window as bellow,it mens This module is started successfully.

A7 0011.jpg

4.Now we can make a telephone calls,
Click on the the number "1" to send the AT command, and you will see "OK" in the receive window,it means the serial port communication no problem.

A7 0012.jpg

Insert the headset into the headset port click on the number"15" to send the AT+SNFS=0 command,if display "0k" means success into headphones mode.

A7 0013.jpg

Click on the number"15" to send the ATDXXXXXXXXX command,"XXXXXXXX"is the phone number you want to call,if display "OK",then start dialing.you can enjoy the call.

A7 0014.jpg

5. Get the GPS information
Connect the GPS Antanna
A7 0015.jpg

AT Command
A7 0016.jpg

Of course not just these functions, you can send some other command to achieve different functions

AT Command Description
AT + CGATT = 1 Return OK, attached to the network
AT + CGACT = 1 Activate the network, then you can use the tcp/ip command
AT + CIPSTART = "TCP" "", 60000 TCPIP server connection
AT + CIPCLOSE Close TCP/IP connection
AT+CMGF=1 Send a text message
AT+CIPTCFG Passthrough mode configuration
AT+CIPTMODE Enter the passthrough mode
AT+GPS=0 Close GPS

With Arduino Leonardo

The demo code below is for the Xduino to send SMS message/dial a voice call/submit a http request to a website and upload datas to the pachube. It has been tested on Arduino Duemilanove but will work on any compatible variant, plesse note that this sketch uses the sorfware UART of ATmega328P. please follow the following steps for running this sketch.

  1. With the A7 GPRS/GSM/GPS Shield removed, download this sketch into your Arduino.
  2. Disconnect the Xduino from USB port to remove power source.
  3. Set the Serial Port jumpers on the A7 GPRS/GSM/GPS Shield in SWserial position, to use the Soft Serial port of Arduino.
  4. Connect the antenna to the A7 GPRS/GSM/GPRS Shield and insert the SIM Card.
  5. Mount the GPRS Shield on Arduino.
  6. Connect the Arduino to the computer by USB, and fire up your favorite serial terminal software on computer, choose the COM port for Arduino, set it to operate at 115200.

A6010.jpg A6012.jpg

  1. Type command in the terminal to execute different function, threr are 4 functions in the demo:
    1. If you input 't', the demo will send a SMS message to another cellphone which you set(you need set the number in the code);
    2. If you input 'd', the program will dial a call to the other cellphone that you set(it is also need you set in the code );
    3. If you input 'h', it will submit a http request to a web that you want to access(it need you set the web adress in the code), it will return a string from the website if it goes correctly;
    4. (Ingnore)If you input 's', it will upload the datas to the pachube(for detail you can refer to the explanation in the code). I strongly recommend you input 'h' before input 's', because uploading datas to the pachube need do some setting, after execute the function of submit a http request, the setting will be set.
  2. If the program returns error in the terminal after you typed the command, don't worry, just try input the command again.
 * Created by Island
 * Modified by keen 
 * Date: 17/03/2017
#define S1debug true
#define S_debug true

void setup()
  Serial1.begin(115200);   // the GPRS baud rate   
  Serial.begin(115200);    // the GPRS baud rate 
void loop()
 * After start up the program, you can using terminal to connect the serial of gprs shield,
 * If you input 't' in the terminal, the program will execute SendTextMessage(), it will show how to send a sms message,
 * If input 'd' in the terminal, it will execute DialVoiceCall(), etc.
  if (Serial.available()){
     case 't':
     case 'd':
     case 'h':
     case 'q':
 * SendTextMessage()
 * This function is to send a sms message
void SendTextMessage()
  SendData("AT+CMGF=1",2000,S1debug);//Because we want to send the SMS in text mode
  SendData("AT+CMGS=+86137xxxxxx",2000,S1debug);//send sms message, be careful need to add a country code before the cellphone number
  SendData("GSM test message!",2000,S1debug);//the content of the message
  Serial1.println((char)26);//the ASCII code of the ctrl+z is 26
 * DialVoiceCall
 * This function is to dial a voice call
void DialVoiceCall()
   SendData("ATD+86137xxxxxx",2000,S1debug);// "ATD+86137xxxxxxxx"dial the number
 * SubmitHttpRequest()
 * This function is submit a HTTP request
 * attention:the time of delay is very important, it must be set enough 
void SubmitHttpRequest(){
   SendData("AT+CREG?",1000,S1debug); //Query network registration
   SendData("AT+CGDCONT=1,\"IP\",\"CMNET\"",2000,S1debug);//setting PDP parameter 
   SendData("AT+CGACT=1,1",2000,S1debug); //Activate PDP, open Internet service
   SendData("AT+CIPSTART=\"TCP\",\"www.baidu.com\",80",5000,S1debug); //Establish TCP connection
   SendData("AT+CIPSEND=10,\"asdfg12345\"",2000,S1debug); //Send string "asdfg12345" and the length of string is 10
   SendData("AT+CIPCLOSE",2000,S1debug);     //Close TCP

void GetSignalQuality(){
     Serial_Print("Getting the sinal quality...",S_debug);
     Serial_Print("Tips:+CSQ: XX,QQ : It means the Signal Quality poorly when the XX less then 10!",S_debug);

void SendData(String command, const int timeout, boolean debug){
    String response = "";    
    long int time = millis();   
    while( (time+timeout) > millis()){
        response += char(Serial1.read());

void Serial_Print(String data, boolean debug){

void RecData(){
    String response = "";    
        response += char(Serial1.read());


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