dma_ex2_repeatedBlockUART.c

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 * Copyright (c) 2017, Texas Instruments Incorporated
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 * *  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"
 
static char String1[] = { "Hello World\r\n" };
 
void main (void)
{
    //Stop Watchdog Timer
    WDT_A_hold(WDT_A_BASE);
 
    //P3.4 = USCI_A0 TXD
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P3,
        GPIO_PIN3
        );
 
    USCI_A_UART_initParam param1 = {0};
    param1.selectClockSource = USCI_A_UART_CLOCKSOURCE_SMCLK;
    param1.clockPrescalar = 6;
    param1.firstModReg = 13;
    param1.secondModReg = 0;
    param1.parity = USCI_A_UART_NO_PARITY;
    param1.msborLsbFirst = USCI_A_UART_LSB_FIRST;
    param1.numberofStopBits = USCI_A_UART_ONE_STOP_BIT;
    param1.uartMode = USCI_A_UART_MODE;
    param1.overSampling = USCI_A_UART_OVERSAMPLING_BAUDRATE_GENERATION;
 
    if (STATUS_FAIL == USCI_A_UART_init(USCI_A0_BASE, &param1)){
        return;
    }
    
    //Enable UART module for operation
    USCI_A_UART_enable(USCI_A0_BASE);
 
 
    //Initialize and Setup DMA Channel 0
    /*
     * Configure DMA channel 0
     * Configure channel for repeated single transfers
     * DMA interrupt flag will be set after every 12 transfers
     * Use DMA Trigger Source 1 (TA0CCR0IFG)
     * Transfer Byte-to-byte
     * Trigger Upon Rising Edge of Trigger Source Signal
     */
    DMA_initParam param2 = {0};
    param2.channelSelect = DMA_CHANNEL_0;
    param2.transferModeSelect = DMA_TRANSFER_REPEATED_SINGLE;
    param2.transferSize = (sizeof String1 - 1);
    param2.triggerSourceSelect = DMA_TRIGGERSOURCE_1;
    param2.transferUnitSelect = DMA_SIZE_SRCBYTE_DSTBYTE;
    param2.triggerTypeSelect = DMA_TRIGGER_RISINGEDGE;
    DMA_init(&param2);
    /*
     * Configure DMA channel 0
     * Use String1 as source
     * Increment source address after every transfer
     */
    DMA_setSrcAddress(DMA_CHANNEL_0,
        (uint32_t)(uintptr_t)String1,
        DMA_DIRECTION_INCREMENT);
    /*
     * Base Address of the DMA Module
     * Configure DMA channel 0
     * Use UART TX Buffer as destination
     * Don't move the destination address after every transfer
     */
    DMA_setDstAddress(DMA_CHANNEL_0,
        USCI_A_UART_getTransmitBufferAddressForDMA(USCI_A0_BASE),
        DMA_DIRECTION_UNCHANGED);
 
    //Enable transfers on DMA channel 0
    DMA_enableTransfers(DMA_CHANNEL_0);
 
    //For DMA0 trigger
    Timer_A_initCompareModeParam initCompareModeParam = {0};
    initCompareModeParam.compareRegister = TIMER_A_CAPTURECOMPARE_REGISTER_2;
    initCompareModeParam.compareInterruptEnable = TIMER_A_CAPTURECOMPARE_INTERRUPT_DISABLE;
    initCompareModeParam.compareOutputMode = TIMER_A_OUTPUTMODE_OUTBITVALUE;
    initCompareModeParam.compareValue = 1;
    Timer_A_initCompareMode(TIMER_A0_BASE, &initCompareModeParam);
 
    //Timer sourced by SMCLK, starts in up-mode
    Timer_A_initUpModeParam initUpModeParam = {0};
    initUpModeParam.clockSource = TIMER_A_CLOCKSOURCE_SMCLK;
    initUpModeParam.clockSourceDivider = TIMER_A_CLOCKSOURCE_DIVIDER_1;
    initUpModeParam.timerPeriod = 0x8192;
    initUpModeParam.timerInterruptEnable_TAIE = TIMER_A_TAIE_INTERRUPT_DISABLE;
    initUpModeParam.captureCompareInterruptEnable_CCR0_CCIE =
        TIMER_A_CAPTURECOMPARE_INTERRUPT_DISABLE;
    initUpModeParam.timerClear = TIMER_A_SKIP_CLEAR;
    initUpModeParam.startTimer = true;
    Timer_A_initUpMode(TIMER_A0_BASE, &initUpModeParam);
    
 
    //Enter LPM3
    _BIS_SR(LPM3_bits);
}