Send data to server using stm32 and GSM/800/900/M66 module With thingspeak

Hi everyone, this blog is to send a data to ThingSpeak server using the STM32 microcontroller.

What are AT commands?

AT commands are commands which are used to control the modems where AT stands for Attention. These commands were derived from Hayes commands which were used by the Hayes smart modems. Every wireless, as well as the dial up modems, require an AT command to interact with a computer machine. These AT commands along with other extended commands also require Hayes command set as a subset.

Requirements:

• STM32F303 Discovery board – 1
• GSM 800/900/M66/M60
• ST-Link Debugger – 1
• FTDI – 1
• Breadboard – 1
• Jumper wires

Usage

The AT commands can be used with GSM module and GPRS MODEMs or phone to access these services and information:

• SMS
• MMS
• Fax
• Voice link and other data over mobile network
• Information and configuration concerning the mobile devices or MODEM and SIM card.

Types of AT Commands:

There are four types of AT commands:

Fig. 1: Image Showing Classification of AT Commands

1)      Test commands – used to check whether a command is supported or not by the MODEM.

SYNTAX:                    AT<command name>=? 

For example:              ATD=?

2)      Read command – used to get mobile phone or MODEM settings for an operation.

SYNTAX:                    AT<command name>?

For example:              AT+CBC?

3)      Set commands – used to modify mobile phone or MODEM settings for an operation.

SYNTAX:                    AT<command name>=value1, value2, …, valueN

Some values in set commands can be optional.

For example:              AT+CSCA=”+xxxxxxxxxx”, 120

4)      Execution commands – used to carry out an operation.

SYNTAX:                    AT<command name>=parameter1, parameter2, …, parameterN

The read commands are not available to get value of last parameter assigned in execution commands because parameters of execution commands are not stored.

For example:               AT+CMSS=1,”+ 9876543210”, 120

1)           AT – This command is used to check communication between the module and the computer.

For example,

AT        

OK

The command returns a result code OK if the computer (serial port) and module are connected properly. If any of module or SIM is not working, it would return a result code ERROR.

2)            +CMGF – This command is used to set the SMS mode. Either text or PDU mode can be selected by assigning 1 or 0 in the command.  

SYNTAX:         AT+CMGF=<mode>

0: for PDU mode

1: for text mode

The text mode of SMS is easier to operate but it allows limited features of SMS. The PDU      (protocol data unit) allows more access to SMS services but the operator requires bit level knowledge of TPDUs. The headers and body of SMS are accessed in hex format in PDU mode so it allows availing more features.

For example,  

                     AT+CMGF=1

                     OK

3)            +CMGW – This command is used to store message in the SIM.

SYNTAX:         AT+CMGW=” Phone number”> Message to be stored Ctrl+z

As one types AT+CMGW and phone number, ‘>’ sign appears on next line where one can type the message. Multiple line messages can be typed in this case. This is why the message is terminated by providing a ‘Ctrl+z’ combination. As Ctrl+z is pressed, the following information response is displayed on the screen.

+CMGW: Number on which message has been stored

4)            +CMGS – This command is used to send a SMS message to a phone number.

SYNTAX:         AT+CMGS= serial number of message to be send.

As the command AT+CMGS and serial number of message are entered, SMS is sent to the particular SIM.

            For example,

            AT+CMGS=1

OK

5)            ATD – This command is used to dial or call a number.

SYNTAX:         ATD<Phone number>;(Enter)

For example,

ATD123456789;

6)            ATA – This command is used to answer a call. An incoming call is indicated by a message ‘RING’ which is repeated for every ring of the call. When the call ends ‘NO CARRIER’ is displayed on the screen. 

SYNTAX:         ATA(Enter)

As ATA followed by enter key is pressed, incoming call is answered.

For example,

RING

RING

ATA

The AT commands for both, GSM module and the mobile phone, are listed below. Some of these commands may not be supported by all the GSM modules available. Also there might be some commands which won’t be supported by some mobile handsets.

List of AT commands:

Testing :

Call control :

Data card Control :

Phone control :

Computer data interface :

Service :

Network Communication parameter :

Miscellaneous :

SMS Text mode :

SMS PDU mode :

List of commands used in this project and their description

TO CHECK THE MODEM WORKING OR NOT :

AT

Response

OK

AT+QIFGCNT Select a Context as Foreground Context

AT+QICSGP Select CSD or GPRS as the Bearer

HAL_UART_Transmit(&huart1, (uint8_t *)”AT+QICSGP=1,\”Airteliot.com\”\r\n”, sizeof(“AT+QICSGP=1,\”Airteliot.com\”\r\n”), 300);

If you are using any other network add related network name.

AT+QIREGAPP Set APN, User Name

HAL_UART_Transmit(&huart1, (uint8_t *)”AT+QIREGAPP\r\n”, sizeof(“AT+QIREGAPP\r\n”), 300);

AT+QIACT Activate GPRS/CSD Context

HAL_UART_Transmit(&huart1, (uint8_t *)”AT+QIACT\r\n”, sizeof(“AT+QIACT\r\n”), 300);

AT+QHTTPGET  //Send GET Request to HTTP server

HAL_UART_Transmit(&huart1, (uint8_t *)”AT+QHTTPGET=40\r\n”, sizeof(“AT+QHTTPGET=80\r\n”), 300);

AT+QHTTPREAD//Read the response of HTTP server

HAL_UART_Transmit(&huart1, (uint8_t *)”AT+QHTTPREAD=60\r\n”, sizeof(“AT+QHTTPREAD=60\r\n”), 300);

AT+QIDEACT //Deactivate PDP context.

HAL_UART_Transmit(&huart1, (uint8_t *)”AT+QIDEACT\r\n”, sizeof(“AT+QIDEACT\r\n”), 300);

CODE

1 st turn on the gsm module

void gsm_on()
{

	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_12, GPIO_PIN_SET);
	HAL_Delay(1000);
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_12, GPIO_PIN_RESET);
	HAL_Delay(1000);
}

Create GSM SEND function

void gsm_cmd(char *cmd, int gsm_delay)
{
		gsm_wait_status=0;
		memset(gsm_buffer,'\0',sizeof(gsm_buffer));
		HAL_UART_Transmit(&huart1,(uint8_t*) cmd, strlen(cmd),1000);
		HAL_Delay(300);
		if(gsm_index>0)
		{
		HAL_Delay(10);
		gsm_index=0;
		gsm_wait_status=1;
		HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, strlen(gsm_buffer), 300);
	
		}
}

Write code to execute the function at commands

while (1)
{
/* USER CODE END WHILE */
  HAL_UART_Transmit(&huart1, (uint8_t *)"AT\r\n", sizeof("AT\r\n"), 300);
  HAL_Delay(300);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);
  HAL_Delay(500);

  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QIFGCNT=0\r\n", sizeof("AT+QIFGCNT=0\r\n"), 300);
  HAL_Delay(500);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);
  HAL_Delay(500);


  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QICSGP=1,\"Airteliot.com\"\r\n", sizeof("AT+QICSGP=1,\"Airteliot.com\"\r\n"), 300);
  HAL_Delay(500);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);
  HAL_Delay(500);

  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QIREGAPP\r\n", sizeof("AT+QIREGAPP\r\n"), 300);
  HAL_Delay(1000);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);
  HAL_Delay(1000);



  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QIACT\r\n", sizeof("AT+QIACT\r\n"), 300);
  HAL_Delay(3000);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);
  HAL_Delay(1000);

  sprintf(url,"AT+QHTTPURL=%d,40\r\n",strlen(http));



  HAL_Delay(2000);
  HAL_UART_Transmit(&huart1, (uint8_t *)url, strlen(url), 300);
  HAL_Delay(1000);

  HAL_UART_Transmit(&huart1, (uint8_t *)http, strlen(http), 300);
      HAL_Delay(1000);

  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QHTTPGET=40\r\n", sizeof("AT+QHTTPGET=80\r\n"), 300);
  HAL_Delay(6000);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);

  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QHTTPREAD=60\r\n", sizeof("AT+QHTTPREAD=60\r\n"), 300);
  HAL_Delay(2000);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);

  HAL_Delay(10000);
  HAL_UART_Transmit(&huart1, (uint8_t *)"AT+QIDEACT\r\n", sizeof("AT+QIDEACT\r\n"), 300);
  HAL_Delay(1000);
  HAL_UART_Transmit(&huart3, (uint8_t *)gsm_buffer, sizeof(gsm_buffer), 300);
}