eusci_b_i2c_ex1_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
 
//******************************************************************************
//  MSP430F5xx_6xx Demo - USCI_B0 I2C Master RX multiple bytes from MSP430 Slave
//
//  Description: This demo connects two MSP430's via the I2C bus. The master
//  reads 5 bytes from the slave. This is the MASTER CODE. The data from the slave
//  transmitter begins at 0 and increments with each transfer.
//  The USCI_B0 RX interrupt is used to know when new data has been received.
//  ACLK = n/a, MCLK = SMCLK = BRCLK =  DCO = ~1MHz
//
//                                /|\  /|\
//               MSP430F67791A     10k  10k     MSP430F67791A
//                   slave         |    |        master
//             -----------------   |    |   -----------------
//           -|XIN  P2.6/UCB0SDA|<-|----+->|P2.6/UCB0SDA  XIN|-
//            |                 |  |       |                 | 32kHz
//           -|XOUT             |  |       |             XOUT|-
//            |     P2.5/UCB0SCL|<-+------>|P2.5/UCB0SCL     |
//            |                 |          |             P1.0|--> LED
//
//******************************************************************************
uint8_t RXData;
void main (void)
{
    WDT_A_hold(WDT_A_BASE);
 
    //Set the XT1 frequency to UCS
    UCS_setExternalClockSource(32768, 0);
 
    //Configure Pins for I2C (UCB0SCL, UCB0SDA)
    //Set P2.5 and P2.6 as Module Function Input
    GPIO_setAsPeripheralModuleFunctionInputPin(
            GPIO_PORT_P2,
            GPIO_PIN5 + GPIO_PIN6
            );
 
    //Init I2C master
    EUSCI_B_I2C_initMasterParam param = {0};
    param.selectClockSource = EUSCI_B_I2C_CLOCKSOURCE_SMCLK;
    param.i2cClk = UCS_getSMCLK();
    param.dataRate = EUSCI_B_I2C_SET_DATA_RATE_400KBPS;
    param.byteCounterThreshold = RXCOUNT;
    param.autoSTOPGeneration = EUSCI_B_I2C_SEND_STOP_AUTOMATICALLY_ON_BYTECOUNT_THRESHOLD;
    EUSCI_B_I2C_initMaster(EUSCI_B0_BASE, &param);
 
    //Specify slave address
    EUSCI_B_I2C_setSlaveAddress(EUSCI_B0_BASE,
            SLAVE_ADDRESS
            );
 
    //Set Master in receive mode
    EUSCI_B_I2C_setMode(EUSCI_B0_BASE,
            EUSCI_B_I2C_RECEIVE_MODE
            );
 
    //Enable I2C Module to start operations
    EUSCI_B_I2C_enable(EUSCI_B0_BASE);
 
    EUSCI_B_I2C_clearInterrupt(EUSCI_B0_BASE,
            EUSCI_B_I2C_RECEIVE_INTERRUPT0 +
            EUSCI_B_I2C_BYTE_COUNTER_INTERRUPT +
            EUSCI_B_I2C_NAK_INTERRUPT
            );
 
    //Enable master Receive interrupt
    EUSCI_B_I2C_enableInterrupt(EUSCI_B0_BASE,
            EUSCI_B_I2C_RECEIVE_INTERRUPT0 +
            EUSCI_B_I2C_BYTE_COUNTER_INTERRUPT +
            EUSCI_B_I2C_NAK_INTERRUPT
            );
 
    //Set P1.0 as an output pin.
    GPIO_setAsOutputPin(
            GPIO_PORT_P1,
            GPIO_PIN0
            );
 
    while (1)
    {
        __delay_cycles(2000);
 
        while (EUSCI_B_I2C_SENDING_STOP ==
                EUSCI_B_I2C_masterIsStopSent(EUSCI_B0_BASE));
 
        EUSCI_B_I2C_masterReceiveStart(EUSCI_B0_BASE);
 
        // Enter LPM0 w/ interrupt
        __bis_SR_register(CPUOFF+GIE);
    }
}
 
#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 USCIB0_ISR(void)
{
    static uint8_t count = 0;
    switch(__even_in_range(UCB0IV, USCI_I2C_UCBIT9IFG))
    {
        case USCI_NONE:             // No interrupts break;
            break;
        case USCI_I2C_UCALIFG:      // Arbitration lost
            break;
        case USCI_I2C_UCNACKIFG:    // NAK received (master only)
            EUSCI_B_I2C_masterReceiveStart(EUSCI_B0_BASE);
            break;
        case USCI_I2C_UCSTTIFG:     // START condition detected with own address (slave mode only)
            break;
        case USCI_I2C_UCSTPIFG:     // STOP condition detected (master & slave mode)
            break;
        case USCI_I2C_UCRXIFG3:     // RXIFG3
            break;
        case USCI_I2C_UCTXIFG3:     // TXIFG3
            break;
        case USCI_I2C_UCRXIFG2:     // RXIFG2
            break;
        case USCI_I2C_UCTXIFG2:     // TXIFG2
            break;
        case USCI_I2C_UCRXIFG1:     // RXIFG1
            break;
        case USCI_I2C_UCTXIFG1:     // TXIFG1
            break;
        case USCI_I2C_UCRXIFG0:     // RXIFG0
            // Get RX data
            RXData = EUSCI_B_I2C_masterReceiveSingle(
                    EUSCI_B0_BASE
                    );
            if (++count >= RXCOUNT) {
                count = 0;
                __bic_SR_register_on_exit(CPUOFF); // Exit LPM0
            }
            break; // Vector 24: RXIFG0 break;
        case USCI_I2C_UCTXIFG0:     // TXIFG0
            break;
        case USCI_I2C_UCBCNTIFG:    // Byte count limit reached (UCBxTBCNT)
            GPIO_toggleOutputOnPin(
                    GPIO_PORT_P1,
                    GPIO_PIN0
                    );
            break;
        case USCI_I2C_UCCLTOIFG:    // Clock low timeout - clock held low too long
            break;
        case USCI_I2C_UCBIT9IFG:    // Generated on 9th bit of a transmit (for debugging)
            break;
        default:
            break;
    }
}