eusci_a_spi_ex1_master.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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 *    from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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//*****************************************************************************
//*****************************************************************************
#include "driverlib.h"
 
uint8_t RXData = 0;
uint8_t TXData = 0;
 
void main(void)
{
    volatile uint16_t i;
 
    //Stop watchdog timer
    WDT_A_hold(WDT_A_BASE);
 
    // Configure Pins for XIN
    //Set P4.1 and P4.2 as Module Function Input.
    /*
 
    * Select Port 4
    * Set Pin 1, 2 to input Module Function, (XIN).
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P4,
        GPIO_PIN1 + GPIO_PIN2,
        GPIO_PRIMARY_MODULE_FUNCTION
    );
 
    //Set external frequency for XT1
    CS_setExternalClockSource(32768);
 
    //Select XT1 as the clock source for SMCLK with no frequency divider
    CS_initClockSignal(CS_SMCLK, CS_XT1CLK_SELECT, CS_CLOCK_DIVIDER_1);
 
    //Start XT1 with no time out
    CS_turnOnXT1(CS_XT1_DRIVE_0);
 
    // Configure SPI Pins for UCA0CLK, UCA0TXD/UCA0SIMO and UCA0RXD/UCA0SOMI
    /*
    * Select Port 1
    * Set Pin 0, Pin 1 and Pin 2 to input Secondary Module Function
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P1,
        GPIO_PIN0 + GPIO_PIN1 + GPIO_PIN2,
        GPIO_PRIMARY_MODULE_FUNCTION
    );
 
    /*
     * Disable the GPIO power-on default high-impedance mode to activate
     * previously configured port settings
     */
    PMM_unlockLPM5();
 
    //Initialize Master
    EUSCI_A_SPI_initMasterParam param = {0};
    param.selectClockSource = EUSCI_A_SPI_CLOCKSOURCE_SMCLK;
    param.clockSourceFrequency = CS_getSMCLK();
    param.desiredSpiClock = 500000;
    param.msbFirst = EUSCI_A_SPI_MSB_FIRST;
    param.clockPhase = EUSCI_A_SPI_PHASE_DATA_CHANGED_ONFIRST_CAPTURED_ON_NEXT;
    param.clockPolarity = EUSCI_A_SPI_CLOCKPOLARITY_INACTIVITY_HIGH;
    param.spiMode = EUSCI_A_SPI_3PIN;
    EUSCI_A_SPI_initMaster(EUSCI_A0_BASE, &param);
 
    //Enable SPI module
    EUSCI_A_SPI_enable(EUSCI_A0_BASE);
 
    //Clear receive interrupt flag
    EUSCI_A_SPI_clearInterrupt(EUSCI_A0_BASE,
          EUSCI_A_SPI_RECEIVE_INTERRUPT
          );
 
    // Enable USCI_A0 RX interrupt
    EUSCI_A_SPI_enableInterrupt(EUSCI_A0_BASE,
                         EUSCI_A_SPI_RECEIVE_INTERRUPT);
 
    //Wait for slave to initialize
    __delay_cycles(100);
 
    TXData = 0x1;                             // Holds TX data
 
    //USCI_A0 TX buffer ready?
    while (!EUSCI_A_SPI_getInterruptStatus(EUSCI_A0_BASE,
              EUSCI_A_SPI_TRANSMIT_INTERRUPT)) ;
 
    //Transmit Data to slave
    EUSCI_A_SPI_transmitData(EUSCI_A0_BASE, TXData);
 
    __bis_SR_register(LPM0_bits + GIE);      // CPU off, enable interrupts
    __no_operation();                       // Remain in LPM0
}
 
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_A0_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_A0_VECTOR)))
#endif
void USCI_A0_ISR(void)
{
    switch(__even_in_range(UCA0IV, USCI_SPI_UCTXIFG))
    {
        case USCI_SPI_UCRXIFG:      // UCRXIFG
            //USCI_A0 TX buffer ready?
            while (!EUSCI_A_SPI_getInterruptStatus(EUSCI_A0_BASE,
                        EUSCI_A_SPI_TRANSMIT_INTERRUPT));
 
            RXData = EUSCI_A_SPI_receiveData(EUSCI_A0_BASE);
 
            //Increment data
            TXData++;
 
            //Send next value
            EUSCI_A_SPI_transmitData(EUSCI_A0_BASE,
                            TXData
                            );
 
            //Delay between transmissions for slave to process information
            __delay_cycles(40);
            break;
        default:
            break;
    }
}