4.2 SAM E70 Xplained Ultra Evaluation Kit

To develop and run the application, follow these steps:

1. Open the main.c file of the project and add the required variables outside the main() function.

   uint8_t __attribute__ ((aligned(32))) Tx[10] = {0x1F, 0x2F, 0x3F, 0x4F, 0x5F, 0x6F, 0x7F, 0x8F, 0x9F, 0xAF};
   uint8_t __attribute__ ((aligned(32)))Rx[10];
   
   /* transfer done flag */
   volatile bool Rx_transfer_done = false;
   volatile bool Tx_transfer_done = false;
   

2. Add the DMA Event Handler for both Tx and Rx outside of the main() function.

   /* This is called after transfer is done */
   void Tx_DMA_EventHandler(XDMAC_TRANSFER_EVENT event, uintptr_t context)
   {
       if (event == XDMAC_TRANSFER_COMPLETE)
       {
           Tx_transfer_done = true;
       }
   }
   
   void Rx_DMA_EventHandler(XDMAC_TRANSFER_EVENT event, uintptr_t context)
   {
       if (event == XDMAC_TRANSFER_COMPLETE)
       {
           Rx_transfer_done = true;
       }
   }
   

3. Add the DMA Callback register function, cache invalidate function, and DMA Channel transfer function.

       XDMAC_ChannelCallbackRegister(XDMAC_CHANNEL_0, Tx_DMA_EventHandler, (uintptr_t)NULL);
       XDMAC_ChannelCallbackRegister(XDMAC_CHANNEL_1, Rx_DMA_EventHandler, (uintptr_t)NULL);
       
       DCACHE_INVALIDATE_BY_ADDR((uint32_t *)Tx, 10);
       DCACHE_INVALIDATE_BY_ADDR((uint32_t *)Rx, 10);
       
       XDMAC_ChannelTransfer(XDMAC_CHANNEL_1, (void *)&SPI0_REGS->SPI_RDR, Rx, sizeof(Rx));
       XDMAC_ChannelTransfer(XDMAC_CHANNEL_0, Tx, (void *)&SPI0_REGS->SPI_TDR, sizeof(Tx));