AnsweredAssumed Answered

STM32 HAL UART Receive Issues

Question asked by farah.ibrahim on May 17, 2016
Latest reply on May 23, 2016 by Amel N
Hi all, 

I have recently run into an issue trying to use the HAL_UART_Receieve() function which comes with the HAL library. I am using the Nucle-F303RE board, which uses the STM32F303RE microcontroller. I was able to get the HAL_UART_Transmit function working, where I used the following block to constantly output text which I read using a python shell on a Linux computer:
while (1)
    char *msg = "Please work \r\n";
    HAL_UART_Transmit(&huart2, (uint8_t *)msg, strlen(msg), 0xFFFF);

The clock, GPIO, and UART settings I have set up are the following:
/** System Clock Configuration
void SystemClock_Config(void)
  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_PeriphCLKInitTypeDef PeriphClkInit;
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0);
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART2;
  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
  /* SysTick_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
/* USART2 init function */
void MX_USART2_UART_Init(void)
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 9600;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONEBIT_SAMPLING_DISABLED ;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
/** Configure pins as
     PA2   ------> USART2_TX
     PA3   ------> USART2_RX
void MX_GPIO_Init(void)
  GPIO_InitTypeDef GPIO_InitStruct;
  /* GPIO Ports Clock Enable */
  /*Configure GPIO pin : B1_Pin */
  GPIO_InitStruct.Pin = B1_Pin;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
  /*Configure GPIO pins : USART_TX_Pin USART_RX_Pin */
  GPIO_InitStruct.Pin = GPIO_PIN_2|GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
  GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
  /*Configure GPIO pin : LD2_Pin */
  GPIO_InitStruct.Pin = LD2_Pin;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
  HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);

Next, I tried to get the HAL_UART_Receieve() function working using the following block, where text would only be printed in the terminal window if the function correctly receives an input:
  uint8_t rx_buffer[1];
  while (1)
      if(HAL_UART_Receive(&huart2, (uint8_t*)rx_buffer, 1, 500) == HAL_OK) {
          char *msg = "Please work \r\n";
          HAL_UART_Transmit(&huart2, (uint8_t *)msg, strlen(msg), 0xFFFF);

However, when I do this, the HAL_UART_Receive function is never returning as HAL_OK or actually receiving my transmission (for more context, in the python shell I am running ser.write('1') where ser is set up to read the port the RS232-device attached to UART2 is plugged in to). I am only sending a single byte, yet it does not seem to picking it up. I am not sure whether my input parameters are correct or not, although my past experience with the HAL library makes me think they are.

I am looking for a potential reason why this isn't working, whether it be a bug in my code or set-up of the STM32 device. Any help is greatly appreciated, and if any further clarification is needed please let me know.