TM4C129EKCPDT: I2C ACK/NACK issue

Hi Archie,

 I'm not familiar with TMP1075NDRLR but does your I2C waveform for reads conform to what is shown in  TMP1075NDRLR  datasheet.

In your code, I don't see you start with a slave address byte. Your first line starts with MAP_I2CMasterDataPut(I2C2_BASE, 0x00) which is writing data to the TX buffer. What is this for? Where are you starting a Slave Address byte for read like shown in the above timing diagram?

Below is an example reading from a I2C device. 

void
I2CReadCommand(uint32_t * pui32DataRx)
{
    //
    // Modify the data direction to true, so that seeing the address will
    // indicate that the I2C Master is initiating a read from the slave.
    //
    MAP_I2CMasterSlaveAddrSet(I2C7_BASE, SHT21_I2C_ADDRESS, true);

    //
    // Setup for first read.  Use I2C_MASTER_CMD_BURST_RECEIVE_START
    // to start a burst mode read.  The I2C master continues to own
    // the bus at the end of this transaction.
    //
    MAP_I2CMasterControl(I2C7_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START);

    //
    // Wait until master module is done transferring.
    // The I2C module has a delay in setting the Busy flag in the register so
    // there needs to be a delay before checking the Busy bit.  The below loops
    // wait until the Busy flag is set, and then wait until it is cleared to
    // indicate that the transaction is complete.  This can take up to 633 CPU
    // cycles @ 100 kbit I2C Baud Rate and 120 MHz System Clock.  Therefore, a
    // while loop is used instead of SysCtlDelay.
    //
    while(!MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    while(MAP_I2CMasterBusy(I2C7_BASE))
    {
    }

    //
    // Read the first byte data from the slave.
    //
    pui32DataRx[0] = MAP_I2CMasterDataGet(I2C7_BASE);

    //
    // Setup for the second read.  Use I2C_MASTER_CMD_BURST_RECEIVE_CONT
    // to continue the burst mode read.  The I2C master continues to own
    // the bus at the end of this transaction.
    //
    MAP_I2CMasterControl(I2C7_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);

    //
    // Wait until master module is done transferring.
    //
    while(!MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    while(MAP_I2CMasterBusy(I2C7_BASE))
    {
    }

    //
    // Read the second byte data from the slave.
    //
    pui32DataRx[1] = MAP_I2CMasterDataGet(I2C7_BASE);

    //
    // Setup for the third read.  Use I2C_MASTER_CMD_BURST_RECEIVE_FINISH
    // to terminate the I2C transaction.  At the end of this transaction,
    // the STOP bit will be issued and the I2C bus is returned to the
    // Idle state.
    //
    MAP_I2CMasterControl(I2C7_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);

    //
    // Wait until master module is done transferring.
    //
    while(!MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    while(MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    
    //
    // Note the third 8-bit data is the checksum byte.  It will be
    // left to the users as an exercise if they want to verify if the
    // checksum is correct.
    pui32DataRx[2] = MAP_I2CMasterDataGet(I2C7_BASE);
}

I don't think your waveform is conforming to the read sequence specified in the TMP1075 datasheet. Look at the waveform below for reading one byte of data from the sensor. In order to read, you need to provide the first frame to which is a slave address byte for WRITE direction. The second frame is to specify the register that you want to read from. The in the third frame you need to provide a slave address byte again for READ direction. The fourth frame is the data returned by the sensor device. In your waveform, I don't see the first two frames. I only see you start with frame 3 followed by three more reads. Can you show the first two frames. 

Archie,

  Thank you for your kind words. Glad the issue is resolved.