STM32H7 UART/USART not working with GPS module (MAX-M10M )

[amirshn]

Hi,

I have connected a MAX-M10M  module to an STM32H7  MCU ( it's custom board) by UART port. I am able to send data to GPS module and also receive config data of it but not able to receive NMEA packets. I only receive the first byte and then the HAL_STATUS of my HAL_UART_RECEIVE function switches to TIMEOUT.( I am using MX CUBE for pin initialization). I have tried blocking mode, IT and DMA, no luck.

Any help would be highly appreciated.

 

 

[Pavel A.]

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[Tesla DeLorean]

Which H7?

What UART? What PINS?

What timeout are you setting? You can get noise, or overrun errors. You can lose data if inattentive as it keeps flowing.

Would be best to use the IT function, filling a buffer, or parsing lines of NMEA data

Here I used HAL to initialize, and then went more register level for interrupts and data handling

https://github.com/cturvey/RandomNinjaChef/blob/main/f746g_disco_gps.c

[amirshn]

Hi 
Thanks for your reply.

I am using STM32H733VGT. I am using USART1 and PINS B6 & B7.( its a custom board)

The timeout does not matter, i have even used HAL_MAX_DELAY. Digging more my UART error code ranges from 4,6 and 14.

I have tried IT and DMA, no difference.

BUT, when i send a "U" (0x55) pattern to the module, i receive all the config of the GPS module ( they are around 400 bytes)( i receive TIMEOUT error in this case too)

 

Here is my code;

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;
 huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
 huart1.Init.ClockPrescaler = UART_PRESCALER_DIV1;
 huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
 if (HAL_UART_Init(&huart1) != HAL_OK)
 {
 Error_Handler();
 }
 if (HAL_UARTEx_SetTxFifoThreshold(&huart1, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
 {
 Error_Handler();
 }
 if (HAL_UARTEx_SetRxFifoThreshold(&huart1, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
 {
 Error_Handler();
 }
 if (HAL_UARTEx_DisableFifoMode(&huart1) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN USART1_Init 2 */
 __HAL_UART_ENABLE_IT(&huart1,UART_IT_ERR);
 __HAL_UART_ENABLE_IT(&huart1,UART_IT_RXNE);

 /* USER CODE END USART1_Init 2 */

}

/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file : main.c
 * @brief : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2025 STMicroelectronics.
 * All rights reserved.
 *
 * This software is licensed under terms that can be found in the LICENSE file
 * in the root directory of this software component.
 * If no LICENSE file comes with this software, it is provided AS-IS.
 *
 ******************************************************************************
 */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "dma.h"
#include "memorymap.h"
#include "usart.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */


/* USER CODE END Includes */

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

/* USER CODE END PTD */

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

/* USER CODE END PD */

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

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

HAL_StatusTypeDef gps_stat;

uint8_t gps_data[100];

/* USER CODE END PV */

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


/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

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

 /* USER CODE BEGIN 1 */

 /* USER CODE END 1 */

 /* MPU Configuration--------------------------------------------------------*/
 MPU_Config();

 /* 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_DMA_Init();
 MX_USART1_UART_Init();
 /* USER CODE BEGIN 2 */

 HAL_GPIO_WritePin(GPIOD, GPIO_PIN_14, GPIO_PIN_RESET);
 HAL_Delay(50);
 HAL_GPIO_WritePin(GPIOD, GPIO_PIN_14, GPIO_PIN_SET);
 HAL_Delay(50);
 uint8_t gps_send = 0x55;


 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_6, GPIO_PIN_SET);
 HAL_Delay(500);
 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_6, GPIO_PIN_RESET);

// gps_stat = HAL_UART_Receive_DMA(&huart1, (uint8_t*)gps_data, sizeof(gps_data));

 /* USER CODE END 2 */

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

 /* USER CODE BEGIN 3 */

	 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_7, GPIO_PIN_SET);
//
	 HAL_Delay(500);

	 gps_stat = HAL_UART_Receive(&huart1, (uint8_t*)gps_data, sizeof(gps_data), 3000);

	 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_7, GPIO_PIN_RESET);

	 HAL_Delay(500);
 }
 /* USER CODE END 3 */
}

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

 /** Supply configuration update enable
 */
 HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);

 /** Configure the main internal regulator output voltage
 */
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

 while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}

 /** 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_DIV1;
 RCC_OscInitStruct.HSICalibrationValue = 64;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
 RCC_OscInitStruct.PLL.PLLM = 4;
 RCC_OscInitStruct.PLL.PLLN = 12;
 RCC_OscInitStruct.PLL.PLLP = 1;
 RCC_OscInitStruct.PLL.PLLQ = 2;
 RCC_OscInitStruct.PLL.PLLR = 2;
 RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_3;
 RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
 RCC_OscInitStruct.PLL.PLLFRACN = 0;
 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_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;
 RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
 RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;

 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
 {
 Error_Handler();
 }
}

/* USER CODE BEGIN 4 */
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	gps_stat = HAL_UART_Receive_DMA(&huart1, (uint8_t*)gps_data, sizeof(gps_data));

// if (huart->Instance == USART1) {
// // Process received data here
//// HAL_UART_Receive_IT(&huart1, (uint8_t*)dma_rx_buf, DMA_BUF_SIZE); // Restart reception
//
//// printf("HAL_UART_ErrorCallback, EC:%d \n",huart1.ErrorCode);
// }

}

//void HAL_UART_ErrorCallback(UART_HandleTypeDef *UartHandle)
//{
//	char message[100] = {0};
//
//	 if (UartHandle->Instance == USART1) //current UART
//	 {
//		 printf("HAL_UART_ErrorCallback, EC:%i \n", UartHandle->ErrorCode);
//
//		__HAL_UART_CLEAR_IT(&huart1, UART_CLEAR_OREF | UART_FLAG_ORE);
//	 }
//}


/* USER CODE END 4 */

 /* MPU Configuration */

void MPU_Config(void)
{
 MPU_Region_InitTypeDef MPU_InitStruct = {0};

 /* Disables the MPU */
 HAL_MPU_Disable();

 /** Initializes and configures the Region and the memory to be protected
 */
 MPU_InitStruct.Enable = MPU_REGION_ENABLE;
 MPU_InitStruct.Number = MPU_REGION_NUMBER0;
 MPU_InitStruct.BaseAddress = 0x0;
 MPU_InitStruct.Size = MPU_REGION_SIZE_4GB;
 MPU_InitStruct.SubRegionDisable = 0x87;
 MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
 MPU_InitStruct.AccessPermission = MPU_REGION_NO_ACCESS;
 MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;
 MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;
 MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
 MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;

 HAL_MPU_ConfigRegion(&MPU_InitStruct);
 /* Enables the MPU */
 HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);

}

/**
 * @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 */

 

[Karl Yamashita]

Let's check the GPS module to be sure it's sending NMEA packets.

Have you checked with oscilloscope to see if you are getting full NMEA packets?

Or try connecting a USB<>UART adapter to view what the GPS is sending.

 

If it is sending full packets, then start showing your code.

[Tesla DeLorean]

Forwarding the data stream can help for quick diagnostics as to what's happening.

https://github.com/cturvey/RandomNinjaChef/blob/main/f746g_disco_fwd.c

https://github.com/cturvey/RandomNinjaChef/blob/main/f411_usart_fwd.c

As I recollect the MAX-M10M outputs at 9600 8N1, other M10 devices are 38400 8N1