AnsweredAssumed Answered

STM32F4xx HAL UART BAUD Timing Issues

Question asked by manderin.tim on Jan 24, 2015
Latest reply on Jan 25, 2015 by Clive One
Hi there... Using the non-hal on an STM32F2xx, I can read/write at 3,333,333 BAUD without a problem. When I port the code to STM32F4xx, I am unable to read/write to the USART1 at the same BAUD rate - instead, it times out.

If I change the baud rate to 4,300,000 - it works. If I change it back to 3,333,333 - it doesn't work. Does anyone have an idea of why this could be happening?

Here is my non-working code...


UART_HandleTypeDef huart1;
  
int main(void) {
  
  HAL_Init();
  
  __GPIOA_CLK_ENABLE();
  __GPIOB_CLK_ENABLE();
  __GPIOC_CLK_ENABLE();
  
  GPIO_InitTypeDef GPIO_InitStruct;
  
  // --------------------------------------------------------------------------- LED
  GPIO_InitStruct.Pin = GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
  
  // --------------------------------------------------------------------------- USART 1
  /**USART1 GPIO Configuration
  PA9      ------> USART1_TX
  PA10     ------> USART1_RX
  PA11     ------> USART1_CTS
  PA12     ------> USART1_RTS
  */
  __USART1_CLK_ENABLE();
  
  GPIO_InitStruct.Pin = GPIO_PIN_9 | GPIO_PIN_10;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
  
  GPIO_InitStruct.Pin = GPIO_PIN_11 | GPIO_PIN_12;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
  
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 3333333;
  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_RTS_CTS;
  huart1.Init.OverSampling = UART_OVERSAMPLING_8;
  HAL_UART_Init(&huart1);
  
  // --------------------------------------------------------------------------- 
  
  for (;;) {
  
    HAL_GPIO_WritePin(GPIOC, GPIO_PIN_15, GPIO_PIN_SET);
    HAL_Delay(250);
  
    HAL_GPIO_WritePin(GPIOC, GPIO_PIN_15, GPIO_PIN_RESET);
    HAL_Delay(250);
  
    HAL_UART_Transmit(&huart1, (uint8_t *)&"Hello", 5, 1000);
  }
}


Outcomes