MSP432P401M: API to send NACK in llC.h file to Communicate with FDC2212 with I2C

/*
 * -------------------------------------------
 *    MSP432 DriverLib - v4_00_00_11 
 * -------------------------------------------
 *
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 * Copyright (c) 2017, Texas Instruments Incorporated
 * All rights reserved.
 *
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 * modification, are permitted provided that the following conditions
 * are met:
 *
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 *    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,
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 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * --/COPYRIGHT--*/
/******************************************************************************
 *  MSP432 I2C - EUSCI_B0_BASE I2C Master TX  bytes to MSP432 Slave - Repeated Start
 *
 *  Description: This demo connects two MSP432 's via the I2C bus. The master
 *  transmits to the slave. This is the MASTER CODE. It continuously
 *  transmits an array of data and demonstrates how to implement an I2C
 *  master transmitter sending multiple bytes followed by a repeated start,
 *  followed by a read of multiple bytes.  This is a common operation for
 *  reading register values from I2C slave devices such as sensors. The
 *  transaction for the I2C that is written looks as follows:
 *
 *  ________________________________________________________________
 *  |  Start   |      |      |  Start   |                   |       |
 *  | 0x48Addr | 0x04 | 0x00 | 0x48Addr |  <10 Byte Read>   | Stop  |
 *  |    W     |      |      |    R     |                   |       |
 *  |__________|______|______|__________|___________________|_______|
 *
 *  ACLK = n/a, MCLK = HSMCLK = SMCLK = BRCLK = default DCO = ~3.0MHz
 *
 *                                /|\  /|\
 *                MSP432P401      10k  10k      MSP432P401
 *                   slave         |    |         master
 *             -----------------   |    |   -----------------
 *            |     P1.6/UCB0SDA|<-|----+->|P1.6/UCB0SDA     |
 *            |                 |  |       |                 |
 *            |                 |  |       |                 |
 *            |     P1.7/UCB0SCL|<-+------>|P1.7/UCB0SCL     |
 *            |                 |          |                 |
 *
 * Author: Timothy Logan
 *****************************************************************************/
/* DriverLib Defines */
#include <ti/devices/msp432p4xx/driverlib/driverlib.h>

/* Standard Defines */
#include <stdint.h>

#include <stdbool.h>
#include <string.h>

/* Slave Address for I2C Slave */
#define SLAVE_ADDRESS       0x48
#define NUM_OF_REC_BYTES    10

/* Variables */
const uint8_t TXData[2] = {0x04, 0x00};
static uint8_t RXData[NUM_OF_REC_BYTES];
static volatile uint32_t xferIndex;
static volatile bool stopSent;

/* I2C Master Configuration Parameter */
const eUSCI_I2C_MasterConfig i2cConfig =
{
        EUSCI_B_I2C_CLOCKSOURCE_SMCLK,          // SMCLK Clock Source
        3000000,                                // SMCLK = 3MHz
        EUSCI_B_I2C_SET_DATA_RATE_100KBPS,      // Desired I2C Clock of 100khz
        0,                                      // No byte counter threshold
        EUSCI_B_I2C_NO_AUTO_STOP                // No Autostop
};

int main(void)
{
    volatile uint32_t ii;

    /* Disabling the Watchdog  */
    MAP_WDT_A_holdTimer();

    /* Select Port 1 for I2C - Set Pin 6, 7 to input Primary Module Function,
     *   (UCB0SIMO/UCB0SDA, UCB0SOMI/UCB0SCL).
     */
    MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P1,
            GPIO_PIN6 + GPIO_PIN7, GPIO_PRIMARY_MODULE_FUNCTION);
    stopSent = false;
    memset(RXData, 0x00, NUM_OF_REC_BYTES);

    /* Initializing I2C Master to SMCLK at 100khz with no autostop */
    MAP_I2C_initMaster(EUSCI_B0_BASE, &i2cConfig);

    /* Specify slave address */
    MAP_I2C_setSlaveAddress(EUSCI_B0_BASE, SLAVE_ADDRESS);

    /* Set Master in transmit mode */
    MAP_I2C_setMode(EUSCI_B0_BASE, EUSCI_B_I2C_TRANSMIT_MODE);

    /* Enable I2C Module to start operations */
    MAP_I2C_enableModule(EUSCI_B0_BASE);

    /* Enable and clear the interrupt flag */
    MAP_I2C_clearInterruptFlag(EUSCI_B0_BASE,
            EUSCI_B_I2C_TRANSMIT_INTERRUPT0 + EUSCI_B_I2C_RECEIVE_INTERRUPT0);
    //Enable master Receive interrupt
    MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
    MAP_Interrupt_enableSleepOnIsrExit();
    MAP_Interrupt_enableInterrupt(INT_EUSCIB0);

    while (1)
    {
        /* Making sure the last transaction has been completely sent out */
        while (MAP_I2C_masterIsStopSent(EUSCI_B0_BASE) == EUSCI_B_I2C_SENDING_STOP);

        /* Send start and the first byte of the transmit buffer. We have to send
         * two bytes to clean out whatever is in the buffer from a previous
         * send  */
        MAP_I2C_masterSendMultiByteStart(EUSCI_B0_BASE, TXData[0]);
        MAP_I2C_masterSendMultiByteNext(EUSCI_B0_BASE, TXData[0]);


        /* Enabling transfer interrupt after stop has been sent */
        MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0);

        /* While the stop condition hasn't been sent out... */
        while(!stopSent)
        {
            MAP_PCM_gotoLPM0InterruptSafe();
        }

        stopSent = false;
    }
}

/*******************************************************************************
 * eUSCIB0 ISR. The repeated start and transmit/receive operations happen
 * within this ISR.
 *******************************************************************************/
void EUSCIB0_IRQHandler(void)
{
    uint_fast16_t status;

    status = MAP_I2C_getEnabledInterruptStatus(EUSCI_B0_BASE);
    MAP_I2C_clearInterruptFlag(EUSCI_B0_BASE, status);

    /* If we reached the transmit interrupt, it means we are at index 1 of
     * the transmit buffer. When doing a repeated start, before we reach the
     * last byte we will need to change the mode to receive mode, set the start
     * condition send bit, and then load the final byte into the TXBUF.
     */
    if (status & EUSCI_B_I2C_TRANSMIT_INTERRUPT0)
    {
        MAP_I2C_masterSendMultiByteNext(EUSCI_B0_BASE, TXData[1]);
        MAP_I2C_disableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
        MAP_I2C_setMode(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_MODE);
        xferIndex = 0;
        MAP_I2C_masterReceiveStart(EUSCI_B0_BASE);
        MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_INTERRUPT0);

    }

    /* Receives bytes into the receive buffer. If we have received all bytes,
     * send a STOP condition */
    if (status & EUSCI_B_I2C_RECEIVE_INTERRUPT0)
    {
        if(xferIndex == NUM_OF_REC_BYTES - 2)
        {
            MAP_I2C_masterReceiveMultiByteStop(EUSCI_B0_BASE);
            RXData[xferIndex++] = MAP_I2C_masterReceiveMultiByteNext(EUSCI_B0_BASE);
        }
        else if(xferIndex == NUM_OF_REC_BYTES - 1)
        {
            RXData[xferIndex++] = MAP_I2C_masterReceiveMultiByteNext(EUSCI_B0_BASE);
            MAP_I2C_disableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_INTERRUPT0);
            MAP_I2C_setMode(EUSCI_B0_BASE, EUSCI_B_I2C_TRANSMIT_MODE);
            xferIndex = 0;
            stopSent = true;
            MAP_Interrupt_disableSleepOnIsrExit();
        }
        else
        {
            RXData[xferIndex++] = MAP_I2C_masterReceiveMultiByteNext(EUSCI_B0_BASE);
        }

    }
}