usci_b_spi_ex1_master.c

Go to the documentation of this file.

/* --COPYRIGHT--,BSD
 * Copyright (c) 2017, Texas Instruments Incorporated
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * *  Redistributions of source code must retain the above copyright
 *    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.
 *
 * *  Neither the name of Texas Instruments Incorporated nor the names of
 *    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"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * --/COPYRIGHT--*/
#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_PIN1 + GPIO_PIN2 + GPIO_PIN3
        );
 
    //Initialize Master
    USCI_B_SPI_initMasterParam param = {0};
    param.selectClockSource = USCI_B_SPI_CLOCKSOURCE_SMCLK;
    param.clockSourceFrequency = UCS_getSMCLK();
    param.desiredSpiClock = SPICLK;
    param.msbFirst = USCI_B_SPI_MSB_FIRST;
    param.clockPhase = USCI_B_SPI_PHASE_DATA_CHANGED_ONFIRST_CAPTURED_ON_NEXT;
    param.clockPolarity = USCI_B_SPI_CLOCKPOLARITY_INACTIVITY_HIGH;
    returnValue =  USCI_B_SPI_initMaster(USCI_B0_BASE, &param);
 
    if (STATUS_FAIL == returnValue){
        return;
    }
 
    //Enable SPI module
    USCI_B_SPI_enable(USCI_B0_BASE);
 
    //Enable Receive interrupt
    USCI_B_SPI_clearInterrupt(USCI_B0_BASE, USCI_B_SPI_RECEIVE_INTERRUPT);
    USCI_B_SPI_enableInterrupt(USCI_B0_BASE, USCI_B_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_B_SPI_getInterruptStatus(USCI_B0_BASE,
               USCI_B_SPI_TRANSMIT_INTERRUPT)) ;
 
    //Transmit Data to slave
    USCI_B_SPI_transmitData(USCI_B0_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_B0_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_B0_VECTOR)))
#endif
void USCI_B0_ISR (void)
{
    switch (__even_in_range(UCB0IV,4)){
        //Vector 2 - RXIFG
        case 2:
            //USCI_A0 TX buffer ready?
            while (!USCI_B_SPI_getInterruptStatus(USCI_B0_BASE,
                       USCI_B_SPI_TRANSMIT_INTERRUPT)) ;
 
            receiveData = USCI_B_SPI_receiveData(USCI_B0_BASE);
 
            //Increment data
            transmitData++;
 
            //Send next value
            USCI_B_SPI_transmitData(USCI_B0_BASE,
            transmitData
            );
 
            //Delay between transmissions for slave to process information
            __delay_cycles(40);
 
            break;
        default: break;
    }
}