dma_ex3_singleTransferSPI.c

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 * Copyright (c) 2017, Texas Instruments Incorporated
 * All rights reserved.
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 *    notice, this list of conditions and the following disclaimer.
 *
 * *  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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//******************************************************************************
//******************************************************************************
 
#include "driverlib.h"
 
char TxString;
char RxString;
 
void main (void)
{
    //Initialize Watchdog in Interval Timer Mode
    /*
     * Base Address of WDT module
     * Use ACLK as clock source to WDT module
     * Divide ACLK by 32k to assert interval every 1 second
     */
    WDT_A_initIntervalTimer(WDT_A_BASE,
        WDT_A_CLOCKSOURCE_ACLK,
        WDT_A_CLOCKDIVIDER_32K);
 
    //Enable Watchdog Interupt
    SFR_clearInterrupt(WDTIE);
    SFR_enableInterrupt(WDTIE);
 
    //Clear P1.0 LED off
    GPIO_setOutputLowOnPin(
 
        GPIO_PORT_P1,
        GPIO_PIN0
        );
 
    //Set P1.0 to output direction
    GPIO_setAsOutputPin(
        GPIO_PORT_P1,
        GPIO_PIN0
        );
 
    //P3.4,3 & P2.7 option select
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P3,
        GPIO_PIN4 + GPIO_PIN3
        );
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P2,
        GPIO_PIN7
        );
 
    //Initialize Master
    USCI_A_SPI_initMasterParam param = {0};
    param.selectClockSource = USCI_A_SPI_CLOCKSOURCE_ACLK;
    param.clockSourceFrequency = UCS_getACLK();
    param.desiredSpiClock = 500000;
    param.msbFirst = USCI_A_SPI_MSB_FIRST;
    param.clockPhase = USCI_A_SPI_PHASE_DATA_CAPTURED_ONFIRST_CHANGED_ON_NEXT;
    param.clockPolarity = USCI_A_SPI_CLOCKPOLARITY_INACTIVITY_HIGH;
    USCI_A_SPI_initMaster(USCI_A0_BASE, &param);
 
    //Enable SPI module
    USCI_A_SPI_enable(USCI_A0_BASE);
 
    //Wait for slave to init
    __delay_cycles(100);
 
    //USCI_A0 TX buffer ready?
    while (!USCI_A_SPI_getInterruptStatus(USCI_A0_BASE, UCTXIFG)) ;
 
 
    //Initialize and Setup DMA Channel 0
    /*
     * Configure DMA channel 0
     * Configure channel for single transfer
     * DMA transfers will be disabled and interrupt flag will be set after every
     *   1 transfer
     * Use DMA Trigger Source 17 (UCA0TXIFG)
     * Transfer Byte-to-byte
     * Trigger transfer on signal held high
     */
    DMA_initParam param0 = {0};
    param0.channelSelect = DMA_CHANNEL_0;
    param0.transferModeSelect = DMA_TRANSFER_SINGLE;
    param0.transferSize = 1;
    param0.triggerSourceSelect = DMA_TRIGGERSOURCE_17;
    param0.transferUnitSelect = DMA_SIZE_SRCBYTE_DSTBYTE;
    param0.triggerTypeSelect = DMA_TRIGGER_HIGH;
    DMA_init(&param0);
    /*
     * Configure DMA channel 0
     * Use TxString as source
     * Increment source address after every transfer
     */
    DMA_setSrcAddress(DMA_CHANNEL_0,
        (uint32_t)(uintptr_t)&TxString,
        DMA_DIRECTION_INCREMENT);
    /*
     * Configure DMA channel 0
     * Use SPI TX Buffer as destination
     * Don't move the destination address after every transfer
     */
    DMA_setDstAddress(DMA_CHANNEL_0,
        USCI_A_SPI_getTransmitBufferAddressForDMA(USCI_A0_BASE),
        DMA_DIRECTION_UNCHANGED);
 
    //Initialize and Setup DMA Channel 1
    /*
     * Configure DMA channel 1
     * Configure channel for single transfer
     * DMA transfers will be disabled and interrupt flag will be set after every
     *   1 transfer
     * Use DMA Trigger Source 16 (UCA0RXIFG)
     * Transfer Byte-to-byte
     * Trigger transfer on signal held high
     */
        
    DMA_initParam param1 = {0};
    param1.channelSelect = DMA_CHANNEL_1;
    param1.transferModeSelect = DMA_TRANSFER_SINGLE;
    param1.transferSize = 1;
    param1.triggerSourceSelect = DMA_TRIGGERSOURCE_16;
    param1.transferUnitSelect = DMA_SIZE_SRCBYTE_DSTBYTE;
    param1.triggerTypeSelect = DMA_TRIGGER_HIGH;
    DMA_init(&param1);
    
    /*
     * Configure DMA channel 1
     * Use SPI RX Buffer as source
     * Don't move the source address after every transfer
     */
    DMA_setSrcAddress(DMA_CHANNEL_1,
        USCI_A_SPI_getReceiveBufferAddressForDMA(USCI_A0_BASE),
        DMA_DIRECTION_UNCHANGED);
    /*
     * Configure DMA channel 1
     * Use RxString as destination
     * Increment destination address after every transfer
     */
    DMA_setDstAddress(DMA_CHANNEL_1,
        (uint32_t)(uintptr_t)&RxString,
        DMA_DIRECTION_INCREMENT);
 
    //Clear TxString && RxString
    TxString = RxString = 0;
 
    //Enter LPM3 w/ interrupts
    __bis_SR_register(LPM3_bits + GIE);
    //For Debugger
    __no_operation();
}
 
//------------------------------------------------------------------------------
//Trigger DMA0 & DMA1 block transfer.
//------------------------------------------------------------------------------
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=WDT_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(WDT_VECTOR)))
#endif
void WDT_A_ISR (void)
{
    if (TxString - 1 == RxString){
        //set P1.0
        GPIO_setOutputHighOnPin(
 
            GPIO_PORT_P1,
            GPIO_PIN0
            );
    } else   {
        //Clear P1.0 LED off
        GPIO_setOutputLowOnPin(
 
            GPIO_PORT_P1,
            GPIO_PIN0
            );
    }
 
    //Increment TxString counter
    TxString++;
 
    //Enable DMA transfers on channel 1
    DMA_enableTransfers(DMA_CHANNEL_1);
 
    //Enable DMA transfers on channel 0
    DMA_enableTransfers(DMA_CHANNEL_0);
}