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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 */
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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 ...

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

@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? :thinking_face:

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

> 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!

 

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.