CCS/MSP430F5529: I2C Diver library usci_b_i2c.c

Part Number: MSP430F5529
Other Parts Discussed in Thread: MSP430WARE

Tool/software: Code Composer Studio

Hi

I use a function from this library to recieve bytes from a slave device.

Here is the original code:

uint8_t USCI_B_I2C_masterReceiveMultiByteFinish (uint16_t baseAddress)
{
    uint8_t receiveData;

    //Send stop condition.
    HWREG8(baseAddress + OFS_UCBxCTL1) |= UCTXSTP;

    //Capture data from receive buffer after setting stop bit due to
    //MSP430 I2C critical timing.
    receiveData = HWREG8(baseAddress + OFS_UCBxRXBUF);

    //Wait for Stop to finish
    while (HWREG8(baseAddress + OFS_UCBxCTL1) & UCTXSTP);

    //Wait for RX buffer
    while (!(HWREG8(baseAddress + OFS_UCBxIFG) & UCRXIFG));

    return receiveData;
}

This code didn't work for my device. However, when I move the data recieve line to the bottom of the code it worked. Am I doing something wrong or is this a bug. My understading is that the processor should recieve the RXIFG interrupt before reading the data not after.

Here is how I modified the code:

uint8_t USCI_B_I2C_masterReceiveMultiByteFinish (uint16_t baseAddress)
{
    uint8_t receiveData;

    //Send stop condition.
    HWREG8(baseAddress + OFS_UCBxCTL1) |= UCTXSTP;

    //Wait for Stop to finish
    while (HWREG8(baseAddress + OFS_UCBxCTL1) & UCTXSTP);

    //Wait for RX buffer
    while (!(HWREG8(baseAddress + OFS_UCBxIFG) & UCRXIFG));

   //Capture data from receive buffer after setting stop bit due to
    //MSP430 I2C critical timing.
    receiveData = HWREG8(baseAddress + OFS_UCBxRXBUF);

    return receiveData;
}