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STM32F407 UART Communication

Question asked by Vaclav Chrascina on May 24, 2018

I am trying to set up a communication between my STM32F4 - Discovery with Open 407V-D development board and a peripheral using UART3 as a RS-485 bus.

I have problem with my communication becouse Rx state of UART remain busy.

Could somebody please explain me what am I doing wrong?

Should I somehow edit HAL_UART_IRQHandler or what setting am I missing?

Here is my code:

#include "main.h" #include "stm32f4xx_hal.h"   UART_HandleTypeDef huart3;  uint8_t Ocular_1_RxBuffer[4];  uint8_t Ocular_1_TxBuffer[2] = {0x01,0x86};  __IO ITStatus UartReady;  void SystemClock_Config(void); static void MX_GPIO_Init(void); static void MX_USART3_UART_Init(void);  int main(void) {    HAL_Init();  SystemClock_Config();   MX_GPIO_Init();  MX_USART3_UART_Init();   HAL_GPIO_WritePin(GPIOB,GPIO_PIN_9,GPIO_PIN_SET);   //set RS 485 into transmit mode  while (1) {     int Timeout = 1000000;  while(huart3.gState != HAL_UART_STATE_READY)        //wait for UART {     Timeout--;     if(Timeout == 0)      Error_Handler(); } Timeout = 1000000; if(HAL_UART_Transmit_IT(&huart3, (uint8_t*)Ocular_1_TxBuffer, 2) != HAL_OK)     //Send request {     Error_Handler(); } while(huart3.RxState != HAL_UART_STATE_READY)                           //wait for UART      {     Timeout--;     if(Timeout == 0)      Error_Handler(); } Timeout = 1000000; if(HAL_UART_Receive_IT(&huart3, (uint8_t*)Ocular_1_RxBuffer, 4) != HAL_OK)                  //Response {     Error_Handler(); } while(UartReady == RESET)                                               //Wait for response {     Timeout--;     if(Timeout == 0)      Error_Handler(); } }   }

I have successfully received response from my peripheral device, but my code generate Error_Handler() after HAL_UART_RxCpltCallback() function. This Error_Handler() occurs in while(UartReady == RESET)loop.

Could somebody please explain this behavior to me?

My callback functions:

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *UartHandle) {   /* Set transmission flag: transfer complete */  HAL_GPIO_WritePin(GPIOB,GPIO_PIN_9,GPIO_PIN_RESET);  UartReady = RESET;  }  void HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle) {  /* Set transmission flag: transfer complete */  HAL_GPIO_WritePin(GPIOB,GPIO_PIN_9,GPIO_PIN_SET);  UartReady = SET; }