Use case: UART TX in DMA mode

Sequence diagram

UART transmit in DMA mode

@startuml participant "User Application" as p1 participant "HAL UART driver" as p2 participant "UARTX_IRQHandler" as p5 participant "DMA" as p3 participant "DMAx_IRQHandler" as p4 == initialization and configuration == == UART HAL Transmit DMA == p1->p2: <color: green> HAL_UART_Transmit_DMA(&huart,aTxBuffer, DATA_TO_SEND_SIZE) note over p2 #00FF00 Transmitting data ongoing end note p2->p3: HAL_DMA_Start_IT() p3-->p2: HAL_OK p2-->p1: HAL_OK p4<-: DMAx complete interrupt p4->p3: HAL_DMA_IRQHandler note over p3 #00FF00 End of transmitting data end note p3->p2: XferCpltCallback p2->p2: Enable UARTx Transmit Complete IRQ (TCIE) p5<-: UARTx Transmit Complete (TCIE) p5->p2: HAL_UART_IRQHandler p2->p1: HAL_UART_TxCpltCallback(huart->TxXferCount) @enduml

Code snippet

HAL1

HAL2 

#define DATA_TO_SEND_SIZE  255

UART_HandleTypeDef huart;

uint8_t aTxBuffer[DATA_TO_SEND_SIZE] = " **** UART Communication **** ";


    /* Ensure that all required peripherals
      (USART, GPIO,NVIC,DMA etc.) are configured properly
    /*
    ...
    */

    /* UART register Transmit complete user callback */
    HAL_UART_RegisterCallback(&huart, HAL_UART_TX_CB_ID,
                              UART_TxCpltCallback);

    /* Start a UART Process in dma mode */
    HAL_UART_Transmit_DMA(&huart, aTxBuffer,
                              DATA_TO_SEND_SIZE)

#define DATA_TO_SEND_SIZE  255

hal_uart_handle_t huart;

uint8_t aTxBuffer[DATA_TO_SEND_SIZE] = " **** UART Communication **** ";


    /* Ensure that all required peripherals
      (USART, GPIO,NVIC,DMA etc.) are configured properly
    /*
    ...
    */

    /* UART register Transmit complete user callback */
    HAL_UART_RegisterTxCpltCallback(&huart, UART_TxCpltCallback);


    /* Start a UART Process in dma mode */
    HAL_UART_Transmit_DMA(&huart, aTxBuffer,
                              DATA_TO_SEND_SIZE)

Key changes

  1. HAL2 DMA start uses HAL_DMA_StartPeriphXfer_IT_Opt() (optional interrupt generation) instead of HAL_DMA_Start_IT().

  2. HAL2 uses byte-oriented transfer count fields (for example tx_xfer_count).