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 */
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.