CODEWITHSUNDEEP
interruptstm32uartstm32f0stm32-hal
guagay_wk
guagay_wk

Reputation: 28090

Cannot transmit every characters through UART

I am using stm32f0 MCU.

I would like to transmit every single byte received from the uart out of the uart. I am enabling an interrupt on every byte received from uart.

My code is quite simple.

uint8_t Rx_data[5]; 

//Interrupt callback routine
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
    if (huart->Instance == USART1)  //current UART
    {
        HAL_UART_Transmit(&huart1, &Rx_data[0], 1, 100);        
        HAL_UART_Receive_IT(&huart1, Rx_data, 1);   //activate UART receive interrupt every time on receiving 1 byte
    }
}

My PC transmits ASCII 12345678 to stm32. If things work as expected, the PC should be receiving 12345678 back. However, the PC receives 1357 instead. What is wrong with the code?

Upvotes: 4

Views: 7170

Answers (3)

Paulo Soares
Paulo Soares

Reputation: 1916

Reenabling interrupts may be inefficient. With a couple of modifications it is possible to keep the interrupt active without needing to write the handler all over again. See the example below altered from the stm32cubemx generator.

/**
* @brief This function handles USART3 to USART6 global interrupts.
*/
void USART3_6_IRQHandler(void)
{
  InterruptGPS(&huart5);
}

void InterruptGPS(UART_HandleTypeDef *huart) {
    uint8_t rbyte;
    if (huart->Instance != USART5) {
        return;
    }
    /* UART in mode Receiver ---------------------------------------------------*/
    if((__HAL_UART_GET_IT(huart, UART_IT_RXNE) == RESET) || (__HAL_UART_GET_IT_SOURCE(huart, UART_IT_RXNE) == RESET)) {
        return;
    }
    rbyte = (uint8_t)(huart->Instance->RDR & (uint8_t)0xff);
    __HAL_UART_SEND_REQ(huart, UART_RXDATA_FLUSH_REQUEST);

    // do your stuff

}

static void init_gps() {
    __HAL_UART_ENABLE_IT(&huart5, UART_IT_RXNE);
}

Upvotes: 7

Stian Skjelstad
Stian Skjelstad

Reputation: 2335

You should make a tx array buffer as well, and use interrupt for writing as well (The first write if not enabled yet, should be sent immediately).

There should be examples of this for STM32 around.

Upvotes: 2

veeman
veeman

Reputation: 800

You should probably switch the two lines: Transmit and Receive. The Transmit function waits for a timeout to send the character, in meantime the next received character is missed.

Upvotes: 1

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