eusci_b_spi_ex1_master.c

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#include "driverlib.h"
 
//*****************************************************************************
//                     MSP430F67791A
//*****************************************************************************
 
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 UCB0CLK, UCB0SIMO, UCB0SOMI
    //Set P2.5, P2.6, P2.7 as Module Function Input.
    GPIO_setAsPeripheralModuleFunctionInputPin(
            GPIO_PORT_P2,
            GPIO_PIN5 + GPIO_PIN6 + GPIO_PIN7
            );
 
    //Set the XT1 frequency to UCS
    UCS_setExternalClockSource(32768, 0);
 
    //Initialize Master
    EUSCI_B_SPI_initMasterParam param = {0};
    param.selectClockSource = EUSCI_B_SPI_CLOCKSOURCE_SMCLK;
    param.clockSourceFrequency = UCS_getSMCLK();
    param.desiredSpiClock = 500000;
    param.msbFirst = EUSCI_B_SPI_MSB_FIRST;
    param.clockPhase = EUSCI_B_SPI_PHASE_DATA_CHANGED_ONFIRST_CAPTURED_ON_NEXT;
    param.clockPolarity = EUSCI_B_SPI_CLOCKPOLARITY_INACTIVITY_HIGH;
    param.spiMode = EUSCI_B_SPI_3PIN;
    EUSCI_B_SPI_initMaster(EUSCI_B0_BASE, &param);
 
    //Enable SPI module
    EUSCI_B_SPI_enable(EUSCI_B0_BASE);
 
    EUSCI_B_SPI_clearInterrupt(EUSCI_B0_BASE,
            EUSCI_B_SPI_RECEIVE_INTERRUPT);
    // Enable USCI_B0 RX interrupt
    EUSCI_B_SPI_enableInterrupt(EUSCI_B0_BASE,
            EUSCI_B_SPI_RECEIVE_INTERRUPT);
 
    //Wait for slave to initialize
    __delay_cycles(100);
 
    TXData = 0x1;                             // Holds TX data
 
    //USCI_B0 TX buffer ready?
    while (!EUSCI_B_SPI_getInterruptStatus(EUSCI_B0_BASE,
                EUSCI_B_SPI_TRANSMIT_INTERRUPT)) ;
 
    //Transmit Data to slave
    EUSCI_B_SPI_transmitData(EUSCI_B0_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_B0_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_B0_VECTOR)))
#endif
void USCI_B0_ISR (void)
{
    switch (__even_in_range(UCB0IV, USCI_SPI_UCTXIFG))
    {
        case USCI_SPI_UCRXIFG:      // UCRXIFG
            //USCI_B0 TX buffer ready?
            while (!EUSCI_B_SPI_getInterruptStatus(EUSCI_B0_BASE,
                        EUSCI_B_SPI_TRANSMIT_INTERRUPT));
 
            RXData = EUSCI_B_SPI_receiveData(EUSCI_B0_BASE);
 
            //Increment data
            TXData++;
 
            //Send next value
            EUSCI_B_SPI_transmitData(EUSCI_B0_BASE,
                    TXData
                    );
 
            //Delay between transmissions for slave to process information
            __delay_cycles(40);
            break;
        default:
            break;
    }
}