AM335x EDMA配制示例

可以参考Starterware的例程中，有个UART_EDMA。

谢谢你的回复。

我用的是uartEcho_edma示例，但是整个工程跑不下来。就会在主函数    UartEDMARxConfTransfer(EDMA3_UART_RX_CHA_NUM, EDMA3_UART_RX_CHA_NUM, rxBuffer, sizeof(rxBuffer)); 下面的while处死掉了，希望能够给予指导，谢谢。

nt main(void)
{
    /* Configure and enable the MMU. */
    MMUConfigAndEnable();

    /* Enable all levels of Cache. */
    CacheEnable(CACHE_ALL);

    /* Configuring the system clocks for EDMA. */
    EDMAModuleClkConfig();

    /* Configuring the system clocks for UART0 instance. */
    UART0ModuleClkConfig();

    /* Performing Pin Multiplexing for UART0 instance. */
    UARTPinMuxSetup(0);

    /* Enabling IRQ in CPSR of ARM processor. */
    IntMasterIRQEnable();

    /* Initializing the ARM Interrupt Controller. */
    IntAINTCInit();

    /* Initializing the EDMA. */
    EDMA3Initialize();

    /* Initializing the UART0 instance for use. */
    UARTInitialize();

    /*
    ** Configuring the EDMA.
    */

    /* Request DMA Channel and TCC for UART Transmit*/
    EDMA3RequestChannel(SOC_EDMA30CC_0_REGS, EDMA3_CHANNEL_TYPE_DMA,
                        EDMA3_UART_TX_CHA_NUM, EDMA3_UART_TX_CHA_NUM,
                        EVT_QUEUE_NUM);

    /* Registering Callback Function for TX*/
    cb_Fxn[EDMA3_UART_TX_CHA_NUM] = &callback;

    /* Request DMA Channel and TCC for UART Receive */
    EDMA3RequestChannel(SOC_EDMA30CC_0_REGS, EDMA3_CHANNEL_TYPE_DMA,
                        EDMA3_UART_RX_CHA_NUM, EDMA3_UART_RX_CHA_NUM,
                        EVT_QUEUE_NUM);

    /* Registering Callback Function for RX*/
    cb_Fxn[EDMA3_UART_RX_CHA_NUM] = &callback;

    /******************** Transmission of a string **************************/

    /* Configuring EDMA PaRAM sets to transmit 'welcome' message. */
    UartEDMATxConfTransfer(EDMA3_UART_TX_CHA_NUM,
                           EDMA3_UART_TX_CHA_NUM,
                           welcome,
                           sizeof(welcome) - 1);

    /* Wait for return from callback */
    while(0 == clBackFlag);
    clBackFlag = 0;

    /******************** Transmission of a string **************************/

    /* Configuring EDMA PaRAM sets to transmit 'intent' message. */
    UartEDMATxConfTransfer(EDMA3_UART_TX_CHA_NUM,
                           EDMA3_UART_TX_CHA_NUM,
                           intent,
                           sizeof(intent) - 1);
 
    /* Wait for return from callback */
    while(0 == clBackFlag);
    clBackFlag = 0;

    /******************** Transmission of a string **************************/

    /* Configuring EDMA PaRAM sets to transmit 'enter' message. */
    UartEDMATxConfTransfer(EDMA3_UART_TX_CHA_NUM,
                           EDMA3_UART_TX_CHA_NUM,
                           enter,
                           sizeof(enter) - 1);
 
    /* Wait for return from callback */
    while(0 == clBackFlag);
    clBackFlag = 0;

    /********************* Receiving Data from User *************************/

    /* Configuring the PaRAM set for reception. */
    UartEDMARxConfTransfer(EDMA3_UART_RX_CHA_NUM,
                           EDMA3_UART_RX_CHA_NUM,
                           rxBuffer,
                           sizeof(rxBuffer));
    
    /* Wait for return from callback */
   while(0 == clBackFlag);     clBackFlag = 0;

    /******************* Echoing received bytes *****************************/

    /* Configuring the PaRAM set to transmit the bytes that were received. */
    UartEDMATxConfTransfer(EDMA3_UART_TX_CHA_NUM,
                           EDMA3_UART_TX_CHA_NUM,
                           rxBuffer,
                           sizeof(rxBuffer));

    /* Wait for return from callback */
    while(0 == clBackFlag);
    clBackFlag = 0;

    /******************* Freeing of allocated channels **********************/

    /* Free EDMA3 Channels for TX and RX */
    EDMA3FreeChannel(SOC_EDMA30CC_0_REGS, EDMA3_CHANNEL_TYPE_DMA,
                     EDMA3_UART_TX_CHA_NUM, EDMA3_TRIG_MODE_EVENT,
                     EDMA3_UART_TX_CHA_NUM, EVT_QUEUE_NUM);

    EDMA3FreeChannel(SOC_EDMA30CC_0_REGS, EDMA3_CHANNEL_TYPE_DMA,
                     EDMA3_UART_RX_CHA_NUM, EDMA3_TRIG_MODE_EVENT,
                     EDMA3_UART_RX_CHA_NUM, EVT_QUEUE_NUM);

    /* Support for Automation Testing. */
    PRINT_RESULT_PASS();

    while(1);
}

谢谢你的回复。用DMA将数据从DDR拷到DDR的这种方式与uart_edma示例在DMA配制上的区别有哪些，谢谢。

谢谢你的回复。我对这个示例我点疑问：就是从串口收数据时，怎么没有通过DMA将数据搬到指定rxBuffer数组里面去，因为通过调试我发现rxBuffer数组里面全是0。

    /* Configuring the PaRAM set for reception. */
    UartEDMARxConfTransfer(EDMA3_UART_RX_CHA_NUM,
                           EDMA3_UART_RX_CHA_NUM,
                           rxBuffer,
                           sizeof(rxBuffer));
    
    /* Wait for return from callback */
    while(0 == clBackFlag);

差别主要是在写parameter表的时候，你要拷贝的源地址和目的地址的差异。用EDMA之前，建议先好好看看TRM手册上面的EDMA章节，说的还是挺详细的。

谢谢你的指导。我拿到的这个Demo示例中怎么从串口通过DMA搬数据，怎么目的数组rxBuffer没有数据，希望能够给予指导下。

    /********************* Receiving Data from User *************************/

    /* Configuring the PaRAM set for reception. */
    UartEDMARxConfTransfer(EDMA3_UART_RX_CHA_NUM,
                           EDMA3_UART_RX_CHA_NUM,
                           rxBuffer,
                           sizeof(rxBuffer));

    /* Wait for return from callback */
    while(0 == clBackFlag);

是的，谢谢你的指导，程序中确实开了Cache，关闭就看到数据了。

你好，将UART_EDMA示例修改为从DDR到DDR的，我只修改目的地址，但是EVENT Num如何进行修改，谢谢。

Steven Liu, 您好，请问一下，修改uart edma，怎样可以实现串口的不定长DMA接收数据？

AM335x的串口接收超时中断Rx timeout interrupt 不能单独使能啊。

谢谢了！

用定时器固定周期的读DMA接收的长度来判断是否接收完成，也可以使用UART的空闲中断来处理