eusci_a_spi_ex1_master.c

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#include "driverlib.h"
//*****************************************************************************
//                   MSP430FR5739
//*****************************************************************************
 
uint8_t RXData =0;
uint8_t TXData = 0;
 
void main(void)
{
  volatile uint16_t i;
 
  //Stop watchdog timer
  WDT_A_hold(WDT_A_BASE);
 
    //Set P1.0 as an output pin.
    /*
 
     * Select Port 1
     * Set Pin 0 as output
     */
    GPIO_setAsOutputPin(
        GPIO_PORT_P1,
        GPIO_PIN0
    );
    //Set P1.0 as Output Low.
    /*
 
    * Select Port 1
    * Set Pin 0 to output Low.
    */
    GPIO_setOutputLowOnPin(
        GPIO_PORT_P1,
        GPIO_PIN0
    );
 
    // Configure Pins for LFXIN
    //Set PJ.4 and PJ.5 as Primary Module Function Input.
    /*
 
    * Select Port J
    * Set Pin 4, 5 to input Primary Module Function, (LFXIN).
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_PJ,
        GPIO_PIN4 + GPIO_PIN5,
        GPIO_PRIMARY_MODULE_FUNCTION
    );
 
  //Set external frequency for XT1
  CS_setExternalClockSource(32768,0);
  //Set DCO frequency to max DCO setting
  CS_setDCOFreq(CS_DCORSEL_0,CS_DCOFSEL_3);
  //Select XT1 as the clock source for ACLK with no frequency divider
  CS_initClockSignal(CS_ACLK,CS_XT1CLK_SELECT,CS_CLOCK_DIVIDER_1);
  //Start XT1 with no time out
  CS_turnOnXT1(CS_XT1_DRIVE_0);
 
    // Configure SPI pins
    // Configure Pins for UCA0CLK
    //Set P1.5 as Secondary Module Function Input.
    /*
 
    * Select Port 1
    * Set Pin 5 to input Secondary Module Function, (UCA0CLK).
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P1,
        GPIO_PIN5,
        GPIO_SECONDARY_MODULE_FUNCTION
    );
    // Configure Pins for UCA0TXD/UCA0SIMO, UCA0RXD/UCA0SOMI
    //Set P2.0, P2.1 as Secondary Module Function Input.
    /*
 
    * Select Port 2
    * Set Pin 0, 1 to input Secondary Module Function, (UCA0TXD/UCA0SIMO, UCA0RXD/UCA0SOMI).
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P2,
        GPIO_PIN0 + GPIO_PIN1,
        GPIO_SECONDARY_MODULE_FUNCTION
    );
 
    //Initialize Master
    EUSCI_A_SPI_initMasterParam param = {0};
    param.selectClockSource = EUSCI_A_SPI_CLOCKSOURCE_ACLK;
    param.clockSourceFrequency = CS_getACLK();
    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);
 
    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,4)){
        //Vector 2 - RXIFG
        case 2:
            //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;
    }
}