usci_b_i2c_ex4_masterRxMultiple.c

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#include "driverlib.h"
 
//*****************************************************************************
//
//*****************************************************************************
 
//*****************************************************************************
//
//Set the address for slave module. This is a 7-bit address sent in the
//following format:
//[A6:A5:A4:A3:A2:A1:A0:RS]
//
//A zero in the "RS" position of the first byte means that the master
//transmits (sends) data to the selected slave, and a one in this position
//means that the master receives data from the slave.
//
//*****************************************************************************
#define SLAVE_ADDRESS 0x48
//*****************************************************************************
//
//Specify Expected Receive data count.
//
//*****************************************************************************
#define RXCOUNT 0x05
 
unsigned char receiveBuffer[10] = { 0x01, 0x01, 0x01, 0x01, 0x01,
                                    0x01, 0x01, 0x01, 0x01, 0x01};
unsigned char *receiveBufferPointer;
unsigned char receiveCount = 0;
 
void main ()
{
    //Stop WDT
    WDT_A_hold(WDT_A_BASE);
 
    //Assign I2C pins to USCI_B0
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P3,
        GPIO_PIN1 + GPIO_PIN2
        );
 
    //Initialize Master
    USCI_B_I2C_initMasterParam param = {0};
    param.selectClockSource = USCI_B_I2C_CLOCKSOURCE_SMCLK;
    param.i2cClk = UCS_getSMCLK();
    param.dataRate = USCI_B_I2C_SET_DATA_RATE_100KBPS;
    USCI_B_I2C_initMaster(USCI_B0_BASE, &param);
 
    //Specify slave address
    USCI_B_I2C_setSlaveAddress(USCI_B0_BASE,
        SLAVE_ADDRESS
        );
 
    //Set receive mode
    USCI_B_I2C_setMode(USCI_B0_BASE,
        USCI_B_I2C_RECEIVE_MODE
        );
 
    //Enable I2C Module to start operations
    USCI_B_I2C_enable(USCI_B0_BASE);
 
    //Enable master Receive interrupt
    USCI_B_I2C_enableInterrupt(USCI_B0_BASE,
            USCI_B_I2C_RECEIVE_INTERRUPT
        );
 
    //wait for bus to be free
    while (USCI_B_I2C_isBusBusy(USCI_B0_BASE )) ;
 
    while (1)
    {
        receiveBufferPointer = (unsigned char *)receiveBuffer;
        receiveCount = RXCOUNT;
 
        //Initialize multi reception
        USCI_B_I2C_masterReceiveMultiByteStart(USCI_B0_BASE);
 
        //Enter low power mode 0 with interrupts enabled.
        __bis_SR_register(LPM0_bits + GIE);
        __no_operation();
    }
}
 
//******************************************************************************
//
//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,12)){
        case USCI_I2C_UCRXIFG:
        {
            //Decrement RX byte counter
            receiveCount--;
 
            if (receiveCount){
                if (receiveCount == 1) {
                    //Initiate end of reception -> Receive byte with NAK
                    *receiveBufferPointer++ =
                        USCI_B_I2C_masterReceiveMultiByteFinish(
                                USCI_B0_BASE
                            );
                }
                else {
                    //Keep receiving one byte at a time
                    *receiveBufferPointer++ = USCI_B_I2C_masterReceiveMultiByteNext(
                            USCI_B0_BASE
                        );
                }
            }
            else {
                //Receive last byte
                *receiveBufferPointer = USCI_B_I2C_masterReceiveMultiByteNext(
                        USCI_B0_BASE
                    );
                __bic_SR_register_on_exit(LPM0_bits);
            }
            break;
        }
    }
}