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location using SIM800L GSM MODULE

veeshaljha
Associate

Hi Community,
I am trying to integrate SIM800L module with STM32F103C6T6 using UART (POLL method), code given below, but all I am getting a response is a single char 'A' or sometimes a random value as shown in screenshots. 
I have also tried setting up the Baud rate at 9600. But no luck, everytime I am getting the HAL_TIMEOUT error message with buffer sometimes a single digit character 'A' or some values from command itself populated in the response buffer. 

Also, I have tried with Putty and it works fine, I get the complete response for a given AT command as expected from manual

live_debug_HALTIMEOUT.PNGresponse.PNG

 

/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <string.h>
#include <stdio.h>

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

uint8_t rx_data[100] = { 0 };
uint8_t test_buffer=90;
uint16_t timeout_tx_rx = 2000;
char AT_OK_RESPONSE[2] = "OK";

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart1;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
static inline uint8_t SendAtCmd(const char *cmd, const char *ack) {

	if (HAL_OK
			== HAL_UART_Transmit(&huart1, (uint8_t*) cmd, strlen(cmd),
					timeout_tx_rx)) {

		HAL_StatusTypeDef rx_response = HAL_UART_Receive(&huart1, rx_data,
				strlen(ack), timeout_tx_rx);
		if (strstr(rx_data, ack) != NULL) {
			return 1;
		}
	}

	return 0;
}

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_USART1_UART_Init();
  /* USER CODE BEGIN 2 */

//	SendAtCmd("AT+IPR=9600\r\n", AT_OK_RESPONSE);
//	SendAtCmd("AT&W\r\n",AT_OK_RESPONSE);

	SendAtCmd("AT\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+CSQ\r\n", "+CSQ");
	SendAtCmd("AT+CREG?\r\n", "+CREG");
	// GPRS init
	SendAtCmd("AT+SAPBR=3,1,\"Contype\",\"GPRS\"\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+SAPBR=3,1,\"APN\",\"airtelgprs.com\"\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+SAPBR=1,1\r\n", AT_OK_RESPONSE);
	// get sim details
	SendAtCmd("AT+CIPGSMLOC=1,1\r\n", "+CIPGSMLOC"); /// geo location
	// put the geo location code here , variables - latitude & longitude

	SendAtCmd("AT+GSN\r\n", AT_OK_RESPONSE); // IMEI D_ID

	SendAtCmd("AT+CCID\r\n", AT_OK_RESPONSE); //CCID S_ID

	SendAtCmd("AT+SAPBR=0,1\r\n", AT_OK_RESPONSE);


  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
	while (1) {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */


	}
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI_DIV2;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL12;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief USART1 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_USART1_UART_Init(void)
{

  /* USER CODE BEGIN USART1_Init 0 */

  /* USER CODE END USART1_Init 0 */

  /* USER CODE BEGIN USART1_Init 1 */

  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 9600;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART1_Init 2 */

  /* USER CODE END USART1_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOD_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
	/* User can add his own implementation to report the HAL error return state */
	__disable_irq();
	while (1) {
	}
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @PAram  file: pointer to the source file name
  * @PAram  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
5 REPLIES 5

The module may echo back what you've sent, as you send the characters; and if you don't read out from UART the characters sent back during transmission, the receiver overflows and stops receiving further characters. So you really may need a duplex (RxTx) process in place. Best, don't use Cube/HAL functions, write your own.

JW


@waclawek.jan wrote:

The module may echo back what you've sent


Indeed.

@veeshaljha - should be easy to check with PuTTY ...

Andrew Neil
Evangelist

@veeshaljha wrote:

POLL method


Maybe you are not polling fast enough?

This seems flawed:

HAL_StatusTypeDef rx_response = HAL_UART_Receive(&huart1, rx_data,
				strlen(ack), timeout_tx_rx);

How do you know exactly what the length of the response will be before it's  arrived?

Are you sure you've correctly accounted for all formatting characters - CR, LF, etc ?

 

Your code only looks at the expected responses:

	SendAtCmd("AT\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+CSQ\r\n", "+CSQ");
	SendAtCmd("AT+CREG?\r\n", "+CREG");
	// GPRS init
	SendAtCmd("AT+SAPBR=3,1,\"Contype\",\"GPRS\"\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+SAPBR=3,1,\"APN\",\"airtelgprs.com\"\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+SAPBR=1,1\r\n", AT_OK_RESPONSE);

You have nothing to deal with any unexpected responses!

Mobile networks are inherently unreliable - you need to be able to cope with failures & unexpected responses!

Also this would require that all unsolicited responses are disabled.

Also:

	SendAtCmd("AT\r\n", AT_OK_RESPONSE);
	SendAtCmd("AT+CSQ\r\n", "+CSQ");
	SendAtCmd("AT+CREG?\r\n", "+CREG");

Note that the correct terminator for AT commands is just CR - no LF is needed.

The extra spurious LF shouldn't hurt - but may affect what gets echoed back ...

 


@veeshaljha wrote:

location using SIM800L GSM MODULE


I don't see where "location" comes into this? 🤔

> I don't see where "location" comes into this? 

That module probably is a GSM+GPS combo. It may also provide some location based on GSM triangulation, I'm not sure about that.

Not relevant to the problem, indeed; just explaining the OP's motivation.

Root of the problem is, that the UART functions in Cube/HAL are quite unsuitable for the vast majority of practical UART applications, and there are no useful examples/guidelines.

Key would be to receive characters into ring buffer in interrupt and process them in main; transmission does not really matter but interrupt is OK for it, too.

JW


@waclawek.jan wrote:

Not relevant to the problem


Indeed.

 


@waclawek.jan wrote:

Key would be to receive characters into ring buffer in interrupt and process them in main; transmission does not really matter but interrupt is OK for it, too.


Absolutely!