eusci_b_i2c_ex2_masterRXMultiple.c

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/*******************************************************************************
 * MSP430i2xx EUSCI_B I2C - Master receive multiple bytes
 *
 * Description: In this example, the device is configured as an I2C master.
 * When the slave has data available it pulls the IRQ line (P1.0) down to
 * tell the master data is ready. The master interrupts on the GPIO transition
 * and starts an I2C read. The first byte of the slave's packet is the length
 * of the packet, including the length byte. The master then continues to
 * read bytes until all data from the packet has been consumed. All data
 * processing is done in the interrupt service routines and the device stays
 * in LPM0. Run this example before starting the corresponding slave example.
 *
 *
 *                                /|\  /|\
 *                MSP430i2041     10k  10k      MSP430i2041
 *                   slave         |    |         master
 *             -----------------   |    |   -----------------
 *            |     P1.6/UCB0SCL|<-|----+->|P1.6/UCB0SCL     |
 *            |                 |  |       |                 |
 *            |                 |  |       |                 |
 *            |     P1.7/UCB0SDA|<-+------>|P1.7/UCB0SDA     |
 *            |                 |          |                 |
 *            |             P1.0|--------->|P1.0             |
 *            |                 |          |                 |
 *
 * Author: Zack Lalanne
 ******************************************************************************/
 
#include "driverlib.h"
 
#define SLAVE_ADDRESS 0x48
 
static uint8_t RXData[4];
static uint16_t RXDataIndex = 0;
static uint16_t NumOfRXBytes;
 
int main(void)
{
    EUSCI_B_I2C_initMasterParam i2cConfig =
    {
        EUSCI_B_I2C_CLOCKSOURCE_SMCLK,          // SMCLK Clock Source
        4096000,                                // SMCLK = 4.096MHz
        EUSCI_B_I2C_SET_DATA_RATE_400KBPS,      // Desired I2C Clock of 400kHz
        0,                                      // No byte counter threshold
        EUSCI_B_I2C_NO_AUTO_STOP                // No Autostop
    };
 
    WDT_hold(WDT_BASE);
 
    // Setting the DCO to use the internal resistor. DCO will be at 16.384MHz
    CS_setupDCO(CS_INTERNAL_RESISTOR);
 
    // Setting SMCLK = DC0 / 4 = 4.096 MHz
    CS_initClockSignal(CS_SMCLK, CS_CLOCK_DIVIDER_4);
 
    // Setting P1.6 and P1.7 as I2C pins
    GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P1,
            GPIO_PIN6 | GPIO_PIN7,
            GPIO_PRIMARY_MODULE_FUNCTION);
 
    // Using P1.0 as slave interrupt pin
    GPIO_setAsInputPin(GPIO_PORT_P1, GPIO_PIN0);
    GPIO_selectInterruptEdge(GPIO_PORT_P1, GPIO_PIN0,
            GPIO_HIGH_TO_LOW_TRANSITION);
    GPIO_clearInterrupt(GPIO_PORT_P1, GPIO_PIN0);
    GPIO_enableInterrupt(GPIO_PORT_P1, GPIO_PIN0);
 
    // Setting up I2C communication at 400kHz using SMCLK
    EUSCI_B_I2C_initMaster(EUSCI_B0_BASE, &i2cConfig);
 
    // Set master in transmit mode
    EUSCI_B_I2C_setMode(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_MODE);
 
    // Settings slave address
    EUSCI_B_I2C_setSlaveAddress(EUSCI_B0_BASE, SLAVE_ADDRESS);
 
    // Enable the module for operation
    EUSCI_B_I2C_enable(EUSCI_B0_BASE);
 
    // Clear needed I2C interrupts
    EUSCI_B_I2C_clearInterrupt(EUSCI_B0_BASE,
            EUSCI_B_I2C_RECEIVE_INTERRUPT0);
 
    // Go to sleep and wait for LPM exit
    __bis_SR_register(LPM0_bits | 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)
{
    switch(__even_in_range(UCB0IV, USCI_I2C_UCBIT9IFG))
    {
        case USCI_NONE: break;
        case USCI_I2C_UCALIFG: break;
        case USCI_I2C_UCNACKIFG: break;
        case USCI_I2C_UCSTTIFG: break;
        case USCI_I2C_UCSTPIFG: break;
        case USCI_I2C_UCRXIFG3: break;
        case USCI_I2C_UCTXIFG3: break;
        case USCI_I2C_UCRXIFG2: break;
        case USCI_I2C_UCTXIFG2: break;
        case USCI_I2C_UCRXIFG1: break;
        case USCI_I2C_UCTXIFG1: break;
        case USCI_I2C_UCRXIFG0:
 
                                // Send stop if second to last byte
                                if(RXDataIndex == NumOfRXBytes - 2)
                                {
                                    EUSCI_B_I2C_masterReceiveMultiByteStop(EUSCI_B0_BASE);
                                }
 
                                RXData[RXDataIndex++] = EUSCI_B_I2C_masterReceiveMultiByteNext(EUSCI_B0_BASE);
 
                                if(RXDataIndex == 1)
                                {
                                    // Save length of packet if first byte
                                    NumOfRXBytes = RXData[0];
                                }
                                else if(RXDataIndex == NumOfRXBytes)
                                {
                                    // Stop receiving data if last byte
                                    EUSCI_B_I2C_disableInterrupt(EUSCI_B0_BASE,
                                            EUSCI_B_I2C_RECEIVE_INTERRUPT0);
                                    GPIO_enableInterrupt(GPIO_PORT_P1, GPIO_PIN0);
                                    RXDataIndex = 0;
                                    NumOfRXBytes = 0;
                                }
                                break;
        case USCI_I2C_UCTXIFG0: break;
        case USCI_I2C_UCBCNTIFG: break;
        case USCI_I2C_UCCLTOIFG: break;
        case USCI_I2C_UCBIT9IFG: break;
        default: break;
    }
}
 
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=PORT1_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(PORT1_VECTOR)))
#endif
void PORT1_ISR(void)
{
    switch(__even_in_range(P1IV, 0x10))
    {
        case 0x00: break;               // No interrupt
        case 0x02:                      // P1.0 interrupt
                   // Initiate an I2C read
                   EUSCI_B_I2C_masterReceiveStart(EUSCI_B0_BASE);
                   EUSCI_B_I2C_enableInterrupt(EUSCI_B0_BASE,
                           EUSCI_B_I2C_RECEIVE_INTERRUPT0);
                   GPIO_disableInterrupt(GPIO_PORT_P1, GPIO_PIN0);
                   break;
        case 0x04: break;               // P1.1 interrupt
        case 0x06: break;               // P1.2 interrupt
        case 0x08: break;               // P1.3 interrupt
        case 0x0A: break;               // P1.4 interrupt
        case 0x0C: break;               // P1.5 interrupt
        case 0x0E: break;               // P1.6 interrupt
        case 0x10: break;               // P1.7 interrupt
    }
}