eusci_b_i2c_ex3_slaveRxMultiple.c

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#include "driverlib.h"
 
//******************************************************************************
//  EUSCI_B0 I2C Slave RX single bytes from MSP430 Master
//
//  Description: This demo connects two MSP430's via the I2C bus. The master
//  transmits to the slave. This is the slave code. The interrupt driven
//  data receiption is demonstrated using the USCI_B0 RX interrupt.
//
//   Tested on MSP430FR5969
//
//                                /|\  /|\
//                                10k  10k
//                   slave         |    |         master
//             -----------------   |    |   -----------------
//           -|XIN  P1.6/UCB0SDA|<-|----+->|P1.6/UCB0SDA  XIN|-
//            |                 |  |       |                 |
//           -|XOUT             |  |       |             XOUT|-
//            |     P1.7/UCB0SCL|<-+------>|P1.7/UCB0SCL     |
//            |                 |          |                 |
//            |                 |          |                 |
//
 
//******************************************************************************
//*****************************************************************************
//
//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
 
uint8_t RXData;
 
void main(void)
{
    WDT_A_hold(WDT_A_BASE);
 
    // Configure Pins for I2C
    //Set P1.6 and P1.7 as Secondary Module Function Input.
    /*
 
    * Select Port 1
    * Set Pin 6, 7 to input Secondary Module Function, (UCB0SIMO/UCB0SDA, UCB0SOMI/UCB0SCL).
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P1,
        GPIO_PIN6 + GPIO_PIN7,
        GPIO_SECONDARY_MODULE_FUNCTION
    );
 
      /*
     * Disable the GPIO power-on default high-impedance mode to activate
     * previously configured port settings
     */
    PMM_unlockLPM5();
 
    // eUSCI configuration
    EUSCI_B_I2C_initSlaveParam param = {0};
    param.slaveAddress = SLAVE_ADDRESS;
    param.slaveAddressOffset = EUSCI_B_I2C_OWN_ADDRESS_OFFSET0;
    param.slaveOwnAddressEnable = EUSCI_B_I2C_OWN_ADDRESS_ENABLE;
    EUSCI_B_I2C_initSlave(EUSCI_B0_BASE, &param);
 
    EUSCI_B_I2C_enable(EUSCI_B0_BASE);
 
    EUSCI_B_I2C_clearInterrupt(EUSCI_B0_BASE,
                EUSCI_B_I2C_RECEIVE_INTERRUPT0
                );
 
    EUSCI_B_I2C_enableInterrupt(EUSCI_B0_BASE,
                EUSCI_B_I2C_RECEIVE_INTERRUPT0
                );
 
    __bis_SR_register(CPUOFF + GIE);        // Enter LPM0 w/ interrupts
    __no_operation();
}
 
//------------------------------------------------------------------------------
// The USCI_B0 data ISR RX vector is used to move received data from the I2C
// master to the MSP430 memory.
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
// The USCI_B0 state ISR TX vector is used to wake up the CPU from LPM0 in order
// to process the received data in the main program. LPM0 is only exit in case
// of a (re-)start or stop condition when actual data was received.
//------------------------------------------------------------------------------
#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)
{
    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)
            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
          RXData = EUSCI_B_I2C_slaveGetData(EUSCI_B0_BASE);
            break;
        case USCI_I2C_UCTXIFG0:     // TXIFG0
            break;
        case USCI_I2C_UCBCNTIFG:    // Byte count limit reached (UCBxTBCNT)
            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;
    }
}