MSP430FR2476: EusciB-I2c - first byte not transmitted starting from second transmission

Hi everyone,

thanks to Bruce's help I am progressing in my project, but I still sometime face issues which are a bit weird.

Now, the problem I am having in this moment is that for some reason, my I2C register write function stops working

properly if I call it more than once. 

I go in the details: to communicate with the device I am using (an ST25DV), I need to send on I2C the following structure

I2CADDRESS | REG_MSB | REG_LSB | DATA_1 | ... | DATA_n | STOP

Essentially, I need to transmit 2 bytes of register address and 1...n bytes of data to write in the register. So far so good.

To do so, I wrote this function based on the EUSCI_I2C driverlib

int ST25DV_register_write(uint8_t * dataBytes, uint16_t memAddress, uint8_t numberOfBytes, uint8_t device_address)
{
    //Specify slave address
    EUSCI_B_I2C_setSlaveAddress(EUSCI_B1_BASE,
        device_address
        );

    //Set in transmit mode
    EUSCI_B_I2C_setMode(EUSCI_B1_BASE,
        EUSCI_B_I2C_TRANSMIT_MODE
        );

    //Enable I2C Module to start operations
    EUSCI_B_I2C_enable(EUSCI_B1_BASE);

    __delay_cycles(1000);
    //Send single byte data.
    EUSCI_B_I2C_masterSendMultiByteStart(EUSCI_B1_BASE,
                                         memAddress >> 8);

    EUSCI_B_I2C_masterSendMultiByteNext(EUSCI_B1_BASE,
                                        memAddress & 0xFF
        );
    while (!EUSCI_B_I2C_getInterruptStatus (EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0)) /*EMPTY*/; // Wait for shift register to finish

    uint8_t totalSent = 0;
    while (totalSent < numberOfBytes - 1)
    {
        EUSCI_B_I2C_masterSendMultiByteNext(EUSCI_B1_BASE,
                                            dataBytes[totalSent]
            );
        totalSent++;
    }
    EUSCI_B_I2C_masterSendMultiByteNext(EUSCI_B1_BASE,
                                        dataBytes[totalSent]
        );

    while (!EUSCI_B_I2C_getInterruptStatus (EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0))
        EUSCI_B_I2C_masterSendMultiByteStop(EUSCI_B1_BASE);
    while (!EUSCI_B_I2C_getInterruptStatus (EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_INTERRUPT0))

    EUSCI_B_I2C_disable(EUSCI_B1_BASE);

    return 0;
}

The initial setup of the I2C (speed, pins etc.) is done once at the beginning.

Now, let's say I want to write "0xA0" in register 0x0000. If this is the first call to the write_register function, I obtain the correct trace reported in the screenshot below.

If I want to do the same operation, but AFTER I already called the write_register function to write something else, this is the trace I get

As you can see, the first byte of the address is missing. 

In a previous discussion here (

MSP430FR2476: Driverlib: Eusci_B I2C multibyte transmission not working - MSP low-power microcontroller...

e2e.ti.com

Part Number: MSP430FR2476 Hello again, I am having a pretty hard time with this I2C, I am glad this forum is so helpful. So here is my new issue. Thanks to

it was suggested to wait for the transmission to end before sending the next byte, and as you can see in the code this is what I am doing.

I tried different combinations of the driverlib functions (for example using a sendNextByte and then sending a Stop at the end of the transmission), 

but I obtain always the same wrong behaviour. I also tried to insert a delay_cycles before staring a new I2C transmission but again, with no luck.

Thanks in advance for the help and have a nice day!

Lorenzo