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MSP432P401R: Could not generate clock for I2C communication

Sushrut Kumar Pattar
Prodigy 380 points

Part Number: MSP432P401R

Hello,

I am trying to establish communication between 2 MSP432P401R's using an example code(i2c_master_rw_repeated_start-master_code), but I am not able to generate clock. I debugged the code, the sequence is not entering the EUSCIB0_IRQHandler. 


Could you kindly let me know what would be the problem. 

Thanks,

Sushrut

  • 0
    TI__Guru 74781 points
    Hello,
    Do you have pullups on the I2C lines? Have you downloaded the corresponding slave code on the other device? Can you try another pair of i2c example code?

    dev.ti.com/.../

    dev.ti.com/.../

    Thanks and Regards,
    Chris
  • 0 in reply to Chris Sterzik
    TI__Prodigy 380 points

    Hello Chris,

    Thank you for your reply.

    It is working now, i had forgotten to connect pull up resistors.

    But I am interfacing an external temperature and humidity sensor to MSP432. I am using master code for MSP432. But i have Arduino files for this sensor. Can i get any files for this sensor which is compatible to MSP432.

    I am using CCS for this.

    I am not able to establish communication between MSP432 and sensor,  any example code that you would suggest to interface external sensors like this.

    Thanks,

    Sushrut

  • 0 in reply to Sushrut Kumar Pattar
    TI__Guru 74781 points
    Sushrut,
    Looking at the datasheet it looks like a repeated start example would work well. dev.ti.com/.../

    You would need to adjust the size of the tx to send the command msb and lsb and then the recieve would just be 6 bytes. There also appears to be some commands that do not have a read that follows so you can use the multibyte master code to send the two bytes.

    Chris
  • 0 in reply to Chris Sterzik
    TI__Prodigy 380 points

    Hi Chris,

    Thank you for your reply.

    I tried with the repeated start example code.

    I have changed the msb and lsb of the tx array in the code. But I am not getting any data from the sensor. The cod sequence is entering into the

    if (status & EUSCI_B_I2C_TRANSMIT_INTERRUPT0), but it is not entering the if (status & EUSCI_B_I2C_RECEIVE_INTERRUPT0).

    Also i did not understand why do i need to use the multi byte master code to send two bytes.

    Could you kindly look into it and let me know what i have missed.i2c_master_rw_repeated_start-master_code_MSP_EXP432P401R_nortos_ccs.rar

    Thanks,

    Sushrut

  • 0 in reply to Sushrut Kumar Pattar
    TI__Prodigy 380 points

    Hi Chris,

    I have added header files of the sensor and made changes in the code to receive data from it, but I not able to get data from sensor.

    I am not using any IRQHandler, I am just using  simple commands to read data.

    Could you kindly look into the attached code and help me out to read the data.

    i2c_slave_initiated_read-master_code_Techchallenge.rar

    Thanks,

    Sushrut

  • 0 in reply to Sushrut Kumar Pattar
    TI__Prodigy 380 points

    Hi Chris,

    I am using repeated start master code.

    I debugged the code line by line to check why the MSP is not communicating with sensor.

    I came to know that the code execution is stopping in MAP_I2C_masterSendMultiByteStart command. I went deeper into the function, then the below while loop is not executing. 

    //Poll for transmit interrupt flag.
    while (!BITBAND_PERI(EUSCI_B_CMSIS(moduleInstance)->rIFG.r, UCTXIFG_OFS));

    Basically i am not able to send the start byte to sensor.

    Could you kindly help me out with this?

    Thanks,

    Sushrut

  • 0 in reply to Sushrut Kumar Pattar
    TI__Guru 74781 points
    Sushrut,
    I looked at the code that you sent and I am unable to find the relevant I2C commands. Maybe this example might help:

    dev.ti.com/.../

    Specficially, refer to the i2c_driver.c (starting at line 177 and 350) and how the tmp007.c is accessed.

    /***********************************************************
    Function:
    */
    bool readI2C(uint8_t ui8Addr, uint8_t ui8Reg, uint8_t *Data, uint8_t ui8ByteCount)
    {
    /* Todo: Put a delay */
    /* Wait until ready */
    while (MAP_I2C_isBusBusy(EUSCI_B1_BASE));

    /* Assign Data to local Pointer */
    pData = Data;

    /* Disable I2C module to make changes */
    MAP_I2C_disableModule(EUSCI_B1_BASE);

    /* Setup the number of bytes to receive */
    i2cConfig.byteCounterThreshold = ui8ByteCount;
    i2cConfig.autoSTOPGeneration = EUSCI_B_I2C_SEND_STOP_AUTOMATICALLY_ON_BYTECOUNT_THRESHOLD;
    MAP_I2C_initMaster(EUSCI_B1_BASE, (const eUSCI_I2C_MasterConfig *)&i2cConfig);

    /* Load device slave address */
    MAP_I2C_setSlaveAddress(EUSCI_B1_BASE, ui8Addr);

    /* Enable I2C Module to start operations */
    MAP_I2C_enableModule(EUSCI_B1_BASE);

    /* Enable master STOP and NACK interrupts */
    MAP_I2C_enableInterrupt(EUSCI_B1_BASE, EUSCI_B_I2C_STOP_INTERRUPT +
    EUSCI_B_I2C_NAK_INTERRUPT);

    /* Set our local state to Busy */
    ui8Status = eUSCI_BUSY;

    /* Send start bit and register */
    MAP_I2C_masterSendMultiByteStart(EUSCI_B1_BASE,ui8Reg);

    /* Enable master interrupt for the remaining data */
    MAP_Interrupt_enableInterrupt(INT_EUSCIB1);

    /* NOTE: If the number of bytes to receive = 1, then as target register is being shifted
    * out during the write phase, UCBxTBCNT will be counted and will trigger STOP bit prematurely
    * If count is > 1, wait for the next TXBUF empty interrupt (just after reg value has been
    * shifted out
    */
    while(ui8Status == eUSCI_BUSY)
    {
    if(MAP_I2C_getInterruptStatus(EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0))
    {
    ui8Status = eUSCI_IDLE;
    }
    }

    ui8Status = eUSCI_BUSY;

    /* Turn off TX and generate RE-Start */
    MAP_I2C_masterReceiveStart(EUSCI_B1_BASE);

    /* Enable RX interrupt */
    MAP_I2C_enableInterrupt(EUSCI_B1_BASE, EUSCI_B_I2C_RECEIVE_INTERRUPT0);

    /* Wait for all data be received */
    while(ui8Status == eUSCI_BUSY)
    {

    #ifdef USE_LPM
    MAP_PCM_gotoLPM0();
    #else
    __no_operation();
    #endif
    }

    /* Disable interrupts */
    MAP_I2C_disableInterrupt(EUSCI_B1_BASE, EUSCI_B_I2C_STOP_INTERRUPT +
    EUSCI_B_I2C_NAK_INTERRUPT + EUSCI_B_I2C_RECEIVE_INTERRUPT0);
    MAP_Interrupt_disableInterrupt(INT_EUSCIB1);

    if(ui8Status == eUSCI_NACK)
    {
    return(false);
    }
    else
    {
    return(true);
    }
    }

    Regards,
    Chris

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