usci_a_spi_ex1_master.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
 *    documentation and/or other materials provided with the distribution.
 *
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 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include "driverlib.h"
 
//*****************************************************************************
//*****************************************************************************
 
//*****************************************************************************
//
//Specify desired frequency of SPI communication
//
//*****************************************************************************
#define SPICLK                          500000
 
uint8_t transmitData = 0x00, receiveData = 0x00;
uint8_t returnValue = 0x00;
 
void main (void)
{
    //Stop watchdog timer
    WDT_A_hold(WDT_A_BASE);
 
    //Set P1.1 for slave reset
    GPIO_setOutputHighOnPin(
 
        GPIO_PORT_P1,
        GPIO_PIN1
        );
 
    //Set P1.1 for slave reset
    //Set P1.0 to output direction
    GPIO_setAsOutputPin(
        GPIO_PORT_P1,
        GPIO_PIN0
        );
 
    //P3.5,4,0 option select
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P3,
        GPIO_PIN5 + GPIO_PIN4 + GPIO_PIN0
        );
 
    //Initialize Master
    USCI_A_SPI_initMasterParam param = {0};
    param.selectClockSource = USCI_A_SPI_CLOCKSOURCE_SMCLK;
    param.clockSourceFrequency = UCS_getSMCLK();
    param.desiredSpiClock = SPICLK;
    param.msbFirst = USCI_A_SPI_MSB_FIRST;
    param.clockPhase = USCI_A_SPI_PHASE_DATA_CHANGED_ONFIRST_CAPTURED_ON_NEXT;
    param.clockPolarity = USCI_A_SPI_CLOCKPOLARITY_INACTIVITY_HIGH;
    returnValue =  USCI_A_SPI_initMaster(USCI_A0_BASE, &param);
 
    if (STATUS_FAIL == returnValue){
        return;
    }
 
    //Enable SPI module
    USCI_A_SPI_enable(USCI_A0_BASE);
 
    //Enable Receive interrupt
    USCI_A_SPI_clearInterrupt(USCI_A0_BASE,
        USCI_A_SPI_RECEIVE_INTERRUPT);
    USCI_A_SPI_enableInterrupt(USCI_A0_BASE,
        USCI_A_SPI_RECEIVE_INTERRUPT);
 
    //Now with SPI signals initialized, reset slave
    GPIO_setOutputLowOnPin(
        GPIO_PORT_P1,
        GPIO_PIN1
        );
 
    //LED On
    GPIO_setOutputHighOnPin(
        GPIO_PORT_P1,
        GPIO_PIN0
        );
 
    //Wait for slave to initialize
    __delay_cycles(100);
 
    //Initialize data values
    transmitData = 0x00;
 
    //USCI_A0 TX buffer ready?
    while (!USCI_A_SPI_getInterruptStatus(USCI_A0_BASE,
               USCI_A_SPI_TRANSMIT_INTERRUPT)) ;
 
    //Transmit Data to slave
    USCI_A_SPI_transmitData(USCI_A0_BASE, transmitData);
 
    //CPU off, enable interrupts
    __bis_SR_register(LPM0_bits + GIE);
}
 
//******************************************************************************
//
//This is the USCI_B0 interrupt vector service routine.
//
//******************************************************************************
#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 (!USCI_A_SPI_getInterruptStatus(USCI_A0_BASE,
                       USCI_A_SPI_TRANSMIT_INTERRUPT)) ;
 
            receiveData = USCI_A_SPI_receiveData(USCI_A0_BASE);
 
            //Increment data
            transmitData++;
 
            //Send next value
            USCI_A_SPI_transmitData(USCI_A0_BASE,
            transmitData
            );
 
            //Delay between transmissions for slave to process information
            __delay_cycles(40);
 
            break;
        default: break;
    }
}