stm32tx

main.c

uint8_t txBuffer[256];
uint8_t txBufferPointer = 0;
uint8_t uartReady = 1;

/**
  * @brief  Sends an amount of data in asynchronous mode.
  * @param  huart: pointer to a UART_HandleTypeDef structure that contains
  *                the configuration information for the specified UART module.
  * @param  pData: Pointer to data buffer
  * @param  Size: Amount of data to be sent
  * @retval HAL status
  */
void HAL_UART_Transmit_Queue(UART_HandleTypeDef *huart, uint8_t* pData, uint16_t size) {
    // append to buffer
    if (txBufferPointer + size > 255) {
        // overflowed
        size = 255 - txBufferPointer;
    }
    memcpy(txBuffer+txBufferPointer, pData, size);
    txBufferPointer += size;
    if (uartReady) {
        HAL_UART_Transmit_IT(huart, txBuffer, txBufferPointer);
        txBufferPointer = 0;
        uartReady = 0;
    }
}

/**
  * @brief  Tx Transfer completed callbacks.
  * @param  huart: pointer to a UART_HandleTypeDef structure that contains
  *                the configuration information for the specified UART module.
  * @retval None
  */
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
    if (txBufferPointer) {
        // continue
        HAL_UART_Transmit_IT(huart, txBuffer, txBufferPointer);
        txBufferPointer = 0;
        uartReady = 0;
    } else {
        uartReady = 1;
    }
}