McSPI with EDMA and DMTimer

Hello,

i have the AM3359 with the ICE-Board. Using CCS5, Sysbios 6.35.01.29, ind_sdk_1.1.01.

I want to use the SPI with DMA and want to write/read via SPI/EDMA continously with a 20kHz DMTimer.

At first i´ve took the example McspiFlash_Edma and sent data out via SPI. (it works, but only one time (single shot)

At which point or with which API function / Registry entry i must work within the DMTimer interrupt to call this procedure (McSPITransfer) ?

Now in the example the function WriteEnable() would be called:

static void WriteEnable(void)
{
    unsigned int dummy = 0;
    unsigned short length = 0;

    //txBuffer[0] = FLASH_WRITE_ENABLE;
    txBuffer[0] = OUTPUTBYTE;
    txBuffer[1] = 0x51;
    txBuffer[2] = 0x53;
    txBuffer[3] = 0x57;
    txBuffer[4] = 0x59;

    length = 5;

    /* Configure the write enable parameters for Edma transfer.*/
    McSpiTxEdmaParamSet(MCSPI_TX_EVENT, MCSPI_TX_EVENT, txBuffer,
                        length);

    /* Configure the write enable parameters for Edma receive.*/
    McSpiRxEdmaParamSet(MCSPI_RX_EVENT, MCSPI_RX_EVENT, (unsigned char *)dummy,
                        length, FALSE);

    /* Register the call-back function for Tx/Rx events of McSPI.*/
    cb_Fxn[MCSPI_TX_EVENT] = &CallBack;
    cb_Fxn[MCSPI_RX_EVENT] = &CallBack;

    McSPITransfer(length);

}

/*
** This function will Assert the Chip select line before transmission, will 
** enable the Edma events for Tx/Rx of McSPI peripheral, will De-assert the 
** Chip select once communication is complete.
*/
static void McSPITransfer(unsigned short length)
{
    /* Set the word count field with the data length to be transferred.*/
    McSPIWordCountSet(SOC_SPI_0_REGS, length);
    
    /* Force the SPIEN to low state.*/
    McSPICSAssert(SOC_SPI_0_REGS, MCSPI_CH_NUM);

    /* Enable the Tx/Rx DMA events for McSPI. */
    McSPIDMAEnable(SOC_SPI_0_REGS, (MCSPI_DMA_RX_EVENT | MCSPI_DMA_TX_EVENT), 
                   MCSPI_CH_NUM);

    /* Enable the McSPI channel for communication.*/
    McSPIChannelEnable(SOC_SPI_0_REGS, MCSPI_CH_NUM);


    /* wait for IPR18 is set / TX complection code
     * EDMA3CC_IPR_I18 (0x00040000u)
     * EDMA3CC_IPR_I18_SHIFT (0x00000012u)
     *
     */
	unsigned int val = 0;
    val = HWREG(SOC_EDMA30CC_0_REGS + EDMA3CC_IPR); //check in debug

    while(EDMA3CC_IPR_I18 !=
    		(HWREG(SOC_EDMA30CC_0_REGS + EDMA3CC_IPR) &
    				EDMA3CC_IPR_I18));

    val = (HWREG(SOC_EDMA30CC_0_REGS + EDMA3CC_IPR) & EDMA3CC_IPR_I18); //check in debug

    /* Force the SPIEN to high state.*/
   McSPICSDeAssert(SOC_SPI_0_REGS, MCSPI_CH_NUM);

    /* Disable the McSPI channel for communication.*/
   McSPIChannelDisable(SOC_SPI_0_REGS, MCSPI_CH_NUM);
}

After McSPIChannelEnable i can see the 5bytes from txBuffer[] sent via SPI out.

After the breakpoint @while() i let the program run with F6 (step over) and when i run the McSPIDeAssert function I can see in Debug-window that the CortexA8 (running) is in in running mode.

But i cannot find the debug cursor.

In the example are also two ISR function Edma3ComplHandlerIsr and Edma3ErrorHandlerIsr, i have a breakpoint in this functions, but i never reach them?!

1. With which funtion/register i can start the SPI/EDMA transfer everaytime in 20kHz period?

2. Is it necassary after data transceive to use these functions McSPICSDeAssert(),    McSPIChannelDisable() and then before new transfer-data to Assert and ChannEnable the McSPI ? ?

Can anyone give me a hint to use SPI/EDMA periodically?

Thank you