MSP432P401R: How to use the clock low time-out select feature (UCCTLO.UCBxCTLW1) to enable a timeout window in I2C communication?

/* --COPYRIGHT--,BSD
 * Copyright (c) 2017, Texas Instruments Incorporated
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * *  Redistributions of source code must retain the above copyright
 *    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,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * --/COPYRIGHT--*/
/******************************************************************************
 *  MSP432 I2C - EUSCI_B0 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 | 0x48Addr |  <10 Byte Read>   | Stop  |
 *  |    W     |      |    R     |                   |       |
 *  |__________|______|__________|___________________|_______|
 *
 *  ACLK = n/a, MCLK = HSMCLK = SMCLK = BRCLK = default DCO = ~3.0MHz
 *
 *                                /|\  /|\
 *                MSP432P4111     10k  10k      MSP432P4111
 *                   slave         |    |         master
 *             -----------------   |    |   -----------------
 *            |     P1.6/UCB0SDA|<-|----+->|P1.6/UCB0SDA     |
 *            |                 |  |       |                 |
 *            |                 |  |       |                 |
 *            |     P1.7/UCB0SCL|<-+------>|P1.7/UCB0SCL     |
 *            |                 |          |                 |
 *
  *****************************************************************************/
/* 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[] = {0x04};
static uint8_t RXData[NUM_OF_REC_BYTES];
static volatile uint32_t xferIndex;
static volatile bool stopSent;
unsigned int i=0, timeout=0;

/* 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)
{
    /* 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);
    // Add clock low timeout , interrupt triggered if slave hold SCL>28ms
    EUSCI_B0->CTLW0 |= EUSCI_A_CTLW0_SWRST;
    EUSCI_B0->CTLW1 |= EUSCI_B_CTLW1_CLTO0;
    EUSCI_B0->CTLW0 &= ~EUSCI_A_CTLW0_SWRST;

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

    /* Enable I2C Module to start operations */
    MAP_I2C_enableModule(EUSCI_B0_BASE);
    MAP_Interrupt_enableInterrupt(INT_EUSCIB0);

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

    MAP_Interrupt_enableSleepOnIsrExit();

    /* Send start and the first byte of the transmit buffer. */
    MAP_I2C_masterSendMultiByteStart(EUSCI_B0_BASE, TXData[0]);

    /* Sent the first byte, now we need to initiate the read */
    xferIndex = 0;
    MAP_I2C_masterReceiveStart(EUSCI_B0_BASE);
    MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_INTERRUPT0);
    // Added line to enable clock low timeout interrupt
    MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_CLOCK_LOW_TIMEOUT_INTERRUPT);
    MAP_PCM_gotoLPM0InterruptSafe();

    P1->DIR |= BIT0;                        // P1.0 set as output
    P1->OUT &= ~BIT0;

    while (1)                               // continuous loop
    {
        if(timeout)
            P1->OUT ^= BIT0;                // Blink P1.0 LED

        for (i = 20000; i > 0; i--);        // Delay
    }
}

/*******************************************************************************
 * 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);
    // check for clock low timeout and blink LED, update timeoutcounter
    if (status & EUSCI_B_I2C_CLOCK_LOW_TIMEOUT_INTERRUPT)
    {
        //increment timeout counter
        timeout++;
    }

    /* 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_disableInterrupt(EUSCI_B0_BASE,
                    EUSCI_B_I2C_RECEIVE_INTERRUPT0);
            MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_STOP_INTERRUPT);

            /*
             * Switch order so that stop is being set during reception of last
             * byte read byte so that next byte can be read.
             */
            MAP_I2C_masterReceiveMultiByteStop(EUSCI_B0_BASE);
            RXData[xferIndex++] = MAP_I2C_masterReceiveMultiByteNext(
                    EUSCI_B0_BASE);
        } else
        {
            RXData[xferIndex++] = MAP_I2C_masterReceiveMultiByteNext(
            EUSCI_B0_BASE);
        }
    }
    else if (status & EUSCI_B_I2C_STOP_INTERRUPT)
    {
        MAP_Interrupt_disableSleepOnIsrExit();
        MAP_I2C_disableInterrupt(EUSCI_B0_BASE,
                                 EUSCI_B_I2C_STOP_INTERRUPT);
    }
}

/* --COPYRIGHT--,BSD,BSD
 * Copyright (c) 2017, Texas Instruments Incorporated
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * *  Redistributions of source code must retain the above copyright
 *    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,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * --/COPYRIGHT--*/
/******************************************************************************
 *  MSP432 I2C - EUSCI_B0 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 | 0x48Addr |  <10 Byte Read>   | Stop  |
 *  |    W     |      |    R     |                   |       |
 *  |__________|______|__________|___________________|_______|
 *
 *  ACLK = n/a, MCLK = HSMCLK = SMCLK = BRCLK = default DCO = ~3.0MHz
 *
 *                                /|\  /|\
 *                MSP432P4111     10k  10k      MSP432P4111
 *                   slave         |    |         master
 *             -----------------   |    |   -----------------
 *            |     P1.6/UCB0SDA|<-|----+->|P1.6/UCB0SDA     |
 *            |                 |  |       |                 |
 *            |                 |  |       |                 |
 *            |     P1.7/UCB0SCL|<-+------>|P1.7/UCB0SCL     |
 *            |                 |          |                 |
 *
 *****************************************************************************/
/* DriverLib Includes */
#include <ti/devices/msp432p4xx/driverlib/driverlib.h>

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

/* Application Defines */
#define SLAVE_ADDRESS       0x48
#define NUM_OF_RX_BYTES        1
#define NUM_OF_TX_BYTES        10

/* Application Variables */
static volatile uint8_t RXData[NUM_OF_RX_BYTES];
static volatile uint32_t xferIndex;
const uint32_t TXData[NUM_OF_TX_BYTES] =
{
     0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99
};

int main(void)
{
    /* Disabling the Watchdog  */
    MAP_WDT_A_holdTimer();
    xferIndex = 0;

    /* 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);

    /* eUSCI I2C Slave Configuration */
    MAP_I2C_initSlave(EUSCI_B0_BASE, SLAVE_ADDRESS, EUSCI_B_I2C_OWN_ADDRESS_OFFSET0,
            EUSCI_B_I2C_OWN_ADDRESS_ENABLE);

    /* Enable the module and enable interrupts */
    MAP_I2C_enableModule(EUSCI_B0_BASE);
    MAP_I2C_clearInterruptFlag(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_INTERRUPT0);
    MAP_I2C_enableInterrupt(EUSCI_B0_BASE, EUSCI_B_I2C_RECEIVE_INTERRUPT0);
    MAP_Interrupt_enableInterrupt(INT_EUSCIB0);
    MAP_Interrupt_enableSleepOnIsrExit();
    MAP_Interrupt_enableMaster();

    /* Sleeping while not in use */
    while (1)
    {
        MAP_PCM_gotoLPM0();
    }
}

/*******************************************************************************
 * 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);

    /* RXIFG */
    if (status & EUSCI_B_I2C_RECEIVE_INTERRUPT0)
    {
        RXData[xferIndex++] = MAP_I2C_slaveGetData(EUSCI_B0_BASE);

        /* Resetting the index if we are at the end */
        if (xferIndex == NUM_OF_RX_BYTES)
        {
            xferIndex = 0;
            MAP_I2C_disableInterrupt(EUSCI_B0_BASE,
                                     EUSCI_B_I2C_RECEIVE_INTERRUPT0);
            MAP_I2C_enableInterrupt(EUSCI_B0_BASE,
                                    EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
        }
    }

    /* TXIFG */
    if (status & EUSCI_B_I2C_TRANSMIT_INTERRUPT0)
    {
        __delay_cycles(90000);
        MAP_I2C_slavePutData(EUSCI_B0_BASE, TXData[xferIndex++]);

        /* Resetting the index if we are at the end */
        if (xferIndex == NUM_OF_TX_BYTES)
        {
            xferIndex = 0;
            MAP_I2C_disableInterrupt(EUSCI_B0_BASE,
                                     EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
            MAP_I2C_enableInterrupt(EUSCI_B0_BASE,
                                    EUSCI_B_I2C_RECEIVE_INTERRUPT0);
        }
    }
}