Hi the example is below.
In this example he is using the function HAL_UART_Receive_DMA which belongs to the HAL_UART module.
He specially raccomands to enable the UART related interrupt and call the HAL_UART_IRQHandler() routine from its ISR.
In a previous example he does the same job but using instead the HAL_DMA_Start_IT function(he is not using the HAL_UART module),
and he doesn t enable the UART related interrupt.
So i suppose he enables the UART interrupt when using the HAL UART module function HAL_UART_Receive_DMA.
But WHY?? i know the answer is here but is not clear to me.
Thank you very much for help!
uint8_t dataArrived = 0;
int main(void) {
HAL_Init();
Nucleo_BSP_Init(); //Configure the UART2
//Configure the DMA1 Channel 5, which is wired to the UART2_RX request line
hdma_usart2_rx.Instance = DMA1_Channel5;
hdma_usart2_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
hdma_usart2_rx.Init.PeriphInc = DMA_PINC_DISABLE;
hdma_usart2_rx.Init.MemInc = DMA_MINC_ENABLE;
hdma_usart2_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hdma_usart2_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hdma_usart2_rx.Init.Mode = DMA_NORMAL;
hdma_usart2_rx.Init.Priority = DMA_PRIORITY_LOW;
HAL_DMA_Init(&hdma_usart2_rx);
//Link the DMA descriptor to the UART2 one
__HAL_LINKDMA(&huart, hdmarx, hdma_usart2_rx);
/* DMA interrupt init */
HAL_NVIC_SetPriority(DMA1_Channel4_5_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel4_5_IRQn);
/* Peripheral interrupt init */
HAL_NVIC_SetPriority(USART2_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(USART2_IRQn);
//Receive three bytes from UART2 in DMA mode
uint8_t data[3];
HAL_UART_Receive_DMA(&huart2, &data, 3);
while(!dataArrived); //Wait for the arrival of data from UART Infinite loop */
while (1);
}
//This callback is automatically called by the HAL when the DMA transfer is completed
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
dataArrived = 1;
}
void DMA1_Channel4_5_IRQHandler(void) {
HAL_DMA_IRQHandler(&hdma_usart2_rx); //This will automatically call the HAL_UART_RxCpltCallback()
}
The author writes:
when we use the HAL module for a given peripheral (HAL_UART in this case), we do
not need to provide our own callbacks: they are defined internally by the HAL, which uses them
to carry out its activities. The HAL offers us the ability to define our corresponding callback
functions (HAL_UART_RxCpltCallback() for UART_RX transfers in DMA mode), which will be
invoked automatically by the HAL, as shown in Figure 7. This rule applies to all HAL modules.
