2026-01-12 3:40 AM - last edited on 2026-01-12 4:33 AM by Andrew Neil
So here is the outline of my code. I'm getting data every 5 seconds (example data: "vref:2975.12, voltage_max:30.00, voltage_min:-1219.00,avg_error: 4136.04") via UART and i transmit it again to view it in putty via ST Link (USART3). Problem is some of the data is getting corrupted, i'm attaching the Putty terminal output.
I have verified the input, using logic analyzer and it's correct.
Here is the code, can you help me identify what i might be doing wrong
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2026 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"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "string.h"
#include "stdio.h"
#include "math.h"
/* 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 ---------------------------------------------------------*/
UART_HandleTypeDef huart5;
UART_HandleTypeDef huart7;
UART_HandleTypeDef huart3;
DMA_HandleTypeDef hdma_uart5_tx;
DMA_HandleTypeDef hdma_usart3_tx;
/* USER CODE BEGIN PV */
char rx_buf[200];
char tx_buf[200];
char temp_buf[200];
char rx_b;
int i = 0;
int tx_busy = 0;
int msg_len = 0;
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MPU_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_UART7_Init(void);
static void MX_USART3_UART_Init(void);
static void MX_UART5_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
//void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart){
//// HAL_UART_Transmit_DMA(&huart3, (uint8_t *)uart_buf, sizeof(uart_buf));
// if(huart->Instance == UART7){
// memcpy(tx_buf, rx_buf, 200);
// HAL_UART_Transmit_IT(&huart3, (uint8_t *)tx_buf, strlen(tx_buf));
//// if(huart->Instance == USART3)
// HAL_UART_Receive_IT(&huart7, (uint8_t*)rx_buf,sizeof(rx_buf) );
// }
//// HAL_UART_Receive_IT(&huart7, (uint8_t*)uart_buf, 200);
//
//}
void echo_to_pc(){
// HAL_UART_Transmit_DMA(&huart3, (uint8_t *)uart_buf, sizeof(uart_buf));
temp_buf[i] = rx_b;
i++;
if (rx_b == '\n') {
if(!tx_busy){
// temp_buf[i] = '\0';
memcpy(tx_buf,temp_buf,i);
msg_len = i;
HAL_UART_Transmit_DMA(&huart3, (uint8_t*) tx_buf, msg_len);
tx_busy = 1;
}
// HAL_UART_Transmit_DMA(&huart5, (uint8_t*) tx_buf, strlen(tx_buf));
i = 0;
}
HAL_UART_Receive_IT(&huart7, (uint8_t*)&rx_b, sizeof(rx_b));
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
if (huart->Instance == UART7) {
echo_to_pc();
}
}
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
// if(huart->Instance == USART3)HAL_UART_Receive_IT(&huart7, (uint8_t*)uart_buf,sizeof(uart_buf) );
if (huart->Instance == USART3) { // Check which UART completed!
tx_busy = 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_UART7_Init();
MX_USART3_UART_Init();
MX_UART5_Init();
/* USER CODE BEGIN 2 */
// sprintf(uart_buf,"hello world %d", 1);
//HAL_UART_Receive_IT(&huart7, (uint8_t*)rx_buf, sizeof(rx_buf));
HAL_UART_Receive_IT(&huart7, (uint8_t*)&rx_b, sizeof(rx_b));
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1) {
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
// HAL_UART_Transmit_DMA(&huart3, (uint8_t *)uart_buf, sizeof(uart_buf));
}
/* 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 = 4;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_3;
RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
RCC_OscInitStruct.PLL.PLLFRACN = 4096;
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();
}
}
/**
* @brief UART5 Initialization Function
* None
* @retval None
*/
static void MX_UART5_Init(void)
{
/* USER CODE BEGIN UART5_Init 0 */
/* USER CODE END UART5_Init 0 */
/* USER CODE BEGIN UART5_Init 1 */
/* USER CODE END UART5_Init 1 */
huart5.Instance = UART5;
huart5.Init.BaudRate = 115200;
huart5.Init.WordLength = UART_WORDLENGTH_8B;
huart5.Init.StopBits = UART_STOPBITS_1;
huart5.Init.Parity = UART_PARITY_NONE;
huart5.Init.Mode = UART_MODE_TX_RX;
huart5.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart5.Init.OverSampling = UART_OVERSAMPLING_16;
huart5.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
huart5.Init.ClockPrescaler = UART_PRESCALER_DIV1;
huart5.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&huart5) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetTxFifoThreshold(&huart5, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetRxFifoThreshold(&huart5, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_DisableFifoMode(&huart5) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN UART5_Init 2 */
/* USER CODE END UART5_Init 2 */
}
/**
* @brief UART7 Initialization Function
* None
* @retval None
*/
static void MX_UART7_Init(void)
{
/* USER CODE BEGIN UART7_Init 0 */
/* USER CODE END UART7_Init 0 */
/* USER CODE BEGIN UART7_Init 1 */
/* USER CODE END UART7_Init 1 */
huart7.Instance = UART7;
huart7.Init.BaudRate = 115200;
huart7.Init.WordLength = UART_WORDLENGTH_8B;
huart7.Init.StopBits = UART_STOPBITS_1;
huart7.Init.Parity = UART_PARITY_NONE;
huart7.Init.Mode = UART_MODE_TX_RX;
huart7.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart7.Init.OverSampling = UART_OVERSAMPLING_16;
huart7.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
huart7.Init.ClockPrescaler = UART_PRESCALER_DIV1;
huart7.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&huart7) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetTxFifoThreshold(&huart7, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetRxFifoThreshold(&huart7, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_DisableFifoMode(&huart7) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN UART7_Init 2 */
/* USER CODE END UART7_Init 2 */
}
/**
* @brief USART3 Initialization Function
* None
* @retval None
*/
static void MX_USART3_UART_Init(void)
{
/* USER CODE BEGIN USART3_Init 0 */
/* USER CODE END USART3_Init 0 */
/* USER CODE BEGIN USART3_Init 1 */
/* USER CODE END USART3_Init 1 */
huart3.Instance = USART3;
huart3.Init.BaudRate = 115200;
huart3.Init.WordLength = UART_WORDLENGTH_8B;
huart3.Init.StopBits = UART_STOPBITS_1;
huart3.Init.Parity = UART_PARITY_NONE;
huart3.Init.Mode = UART_MODE_TX_RX;
huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart3.Init.OverSampling = UART_OVERSAMPLING_16;
huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
huart3.Init.ClockPrescaler = UART_PRESCALER_DIV1;
huart3.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&huart3) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetTxFifoThreshold(&huart3, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetRxFifoThreshold(&huart3, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_DisableFifoMode(&huart3) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART3_Init 2 */
/* USER CODE END USART3_Init 2 */
}
/**
* Enable DMA controller clock
*/
static void MX_DMA_Init(void)
{
/* DMA controller clock enable */
__HAL_RCC_DMA1_CLK_ENABLE();
/* DMA interrupt init */
/* DMA1_Stream0_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA1_Stream0_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Stream0_IRQn);
/* DMA1_Stream1_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA1_Stream1_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Stream1_IRQn);
}
/**
* @brief GPIO Initialization Function
* None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOF_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOE_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOB, LED_GREEN_Pin|LED_RED_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(LED_YELLOW_GPIO_Port, LED_YELLOW_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : B1_Pin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : LED_GREEN_Pin LED_RED_Pin */
GPIO_InitStruct.Pin = LED_GREEN_Pin|LED_RED_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/*Configure GPIO pin : LED_YELLOW_Pin */
GPIO_InitStruct.Pin = LED_YELLOW_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LED_YELLOW_GPIO_Port, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
/* 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.
* file: pointer to the source file name
* 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 */
Solved! Go to Solution.
2026-01-14 12:52 AM
2026-01-12 4:01 AM
Looks like a timing problem.
> ... and i transmit it again to view it in putty via ST Link (USART3).
Not sure if you are aware, this happens within interrupt context (HAL_UART_RxCpltCallback()), thus blocking the same UART interrupt, and other interrupts with identical and lower priority.
2026-01-12 5:58 AM - edited 2026-01-12 5:59 AM
Output a clock signal to verify timing is correct between the chip and whatever is receiving on the other end.
Do a bound check on i before writing.
2026-01-14 12:14 AM
@TDK @Ozone Guys it was not a software problem.
This is what was happening , i have two STM32H723ZG , one is nucleo and other is custom. I'm sending data from custom and sending it to Nucleo H723ZG via UART (UART7). From there i'm sending it to USART3 (ST-Link Virtual COM port) , so i can view the data in PuTTY in PC.
Earlier the problem was data getting corrupted on transit, so i tried different things and nothing worked. Then i just plugged the STLINK of custom board to my PC, then the data starts arriving correcly, if i unplug the ST-Link data starts to corrupt again.
When i use a logic analyzer to read from custom board, i have no issue.
What could be the possible issue?
see how the data arrives before and after plugging ST-Link
Custom board is powered by battery, It is getting 3.3V at VDD pin
2026-01-14 12:24 AM
> Guys it was not a software problem.
I'm pretty sure this is the problem.
> Then i just plugged the STLINK of custom board to my PC, then the data starts arriving correcly, if i unplug the ST-Link data starts to corrupt again.
Removing the serial adapter (VCP) on the remote site does not affect the Tx side of the MCU, but surely the Rx side.
You would need to check and validate the timing of your application.
2026-01-14 12:52 AM