DMA Configuration & Integration

/* DMA configuration: ADC -> RAM for engine sensor group */
/* ADC triggers DMA on each conversion complete; no CPU involvement */
#include "Dma.h"
#include "Adc.h"

#define DMA_CH_ADC_ENGINE    ((Dma_ChannelType)4u)
#define ADC_RESULT_REG_BASE  0xF0024800u  /* Aurix VADC result register */
#define ADC_GROUP_SIZE       4u            /* 4 channels */

static uint16 g_adc_dma_buffer[ADC_GROUP_SIZE];  /* DMA writes here */

const Dma_ChannelConfigType Dma_ChannelConfig[] = {
    {
        .DmaChannelId       = DMA_CH_ADC_ENGINE,
        .DmaSrcAddr         = ADC_RESULT_REG_BASE,  /* ADC result registers */
        .DmaDestAddr        = (uint32)g_adc_dma_buffer,
        .DmaTransferCount   = ADC_GROUP_SIZE,
        .DmaDataWidth       = DMA_WIDTH_16BIT,
        .DmaSrcAddrInc      = DMA_ADDR_INC_4,       /* step 4 bytes between results */
        .DmaDestAddrInc     = DMA_ADDR_INC_2,       /* step 2 bytes in buffer */
        .DmaTriggerSource   = DMA_TRIG_ADC0_GROUP0, /* ADC hardware trigger */
        .DmaTransferComplete= Dma_Adc_TransferComplete, /* ISR callback */
    },
};

/* ISR: fires after DMA copies all 4 ADC results to g_adc_dma_buffer */
void Dma_Adc_TransferComplete(void)
{
    /* g_adc_dma_buffer now has fresh ADC results */
    /* No Adc_ReadGroup() call needed -- DMA already copied data */
    IoHwAb_SetAdcGroupReady(IOHWAB_GROUP_ENGINE_SENSORS);
}

/* DMA-assisted SPI: transfer 256-byte buffer to external flash */
/* Without DMA: CPU writes each byte to SPI FIFO (256 interrupts) */
/* With DMA:    CPU sets up DMA once; DMA feeds SPI FIFO autonomously */

#include "Spi.h"
#include "Dma.h"

static uint8 g_spi_tx_buf[256];
static uint8 g_spi_rx_buf[256];

/* For large SPI transfers, MCAL Spi driver uses DMA internally */
/* Configuration: SpiDmaChannelRef in SPI ARXML config */
/*   SpiHwUnit QSPI0: DmaTxChannel = DMA_CH_SPI0_TX (channel 8) */
/*                   DmaRxChannel = DMA_CH_SPI0_RX (channel 9) */

/* When Spi_AsyncTransmit() is called for a sequence with >4 bytes, */
/* the Spi MCAL driver automatically uses DMA instead of interrupt */
/* mode, transparent to the caller: */

void ExternalFlash_Write(const uint8* data, uint16 len)
{
    uint16 i;
    for (i = 0; i < len; i++) g_spi_tx_buf[i] = data[i];

    /* Set up External Buffer (EB) channel for variable-length transfer */
    Spi_SetupEB(SPI_CH_EXTFLASH_DATA, g_spi_tx_buf, g_spi_rx_buf, len);

    /* SPI MCAL uses DMA internally for this 256-byte transfer */
    /* CPU is free during the 128 us transfer at 2 MHz */
    Spi_AsyncTransmit(SPI_SEQ_EXTFLASH_WRITE);
}