EVM430-FR6047: I2C clock synchronization

Hi Lasse,

Can you explain a bit about the code running on the CC1310:

1) What SimpleLink CC13x0 SDK are you using?

2) What example project is you application based on?

3) What tasks are defined on the device and what tasks are running simultaneously with the I2C?

Thank you for your reply Marie.

In reply to your questions this is what I have:

0) I think I forgot to mention that I have checked the voltage at SDA and SCL which are good, so the pull-up resistors are okay.

1) Simplelink SDK: simplelink_cc13x0_sdk_3_20_00_23

2) The project is originally based on the i2ctmp project (but not much remain from that apart from the I2C_init part)

3) I have 1 task running - mainThread - which calls my setparameters() function.

So it should be the only task running. At the time of writing the original post setparameters() was called in a while(1) loop

while(1)
{
setparameters();
sleep(1); //had a breakpoint here and then checked the MSP for the parameters
}

As you can see in the first post this function then calls a I2CCommunications function which does this:

bool I2CCommunication(struct I2CtransactionStruct *CommStruct)
{

i2c = I2C_open(Board_I2C0, &i2cParams);

    if (CommStruct->write) 
{
        i2cTransaction.writeBuf = Write_buffer;
        i2cTransaction.writeCount = CommStruct->length;
        i2cTransaction.readBuf = 0;
        i2cTransaction.readCount = 0;
    } else (!CommStruct->write) {
        i2cTransaction.writeBuf = 0;
        i2cTransaction.writeCount = 0;
        i2cTransaction.readBuf = Read_buffer;
        i2cTransaction.readCount = CommStruct->length;
    }

//Prepare write message if CommStruct->write

  //loop to handle each transmitted or received package
    while (CommStruct->count-- > 0) {

        if (CommStruct->wait) {
            //sem_res_bool = Semaphore_pend(captureSem, (7000 * (1000 / Clock_tickPeriod)));

            while (GPIO_read(Board_DIO1) == 1) {
                //Do nothing
            }
            interrupt_counter++;
            //sem_res = sem_timedwait(&captureSem, &ts);

        }

        if ((res = I2C_transfer(i2c, Transaction) == true)) {
        } else {
            I2C_close(i2c);
            return false;
        }

//unpack package if it was a received package
}

I have highlighted some code which solved some of the issues.

I have commented the semaphore part out (tried both your API and POSIX). This part waits for the COMM_IRQ line interrupt when I expect a read package.
Without the semaphore but just a simple while loop it actually works as planned.

However, the clock synchronization part remains (sorry about the IRQ line just being capped).



So to sum up.
1) I can set the parameters without the semaphores (will have to try again with that part later)
2) The update valid flag is now set
3) It works even though I have the clock synchronization problem

TI's I2C troubleshooting guide (I think it was there) mentioned that even though clk sync is part of the I2C protocol, its preferable to avoid it. So the question remains why its there?
But perhaps its not that easy a question to answer.

Hi Lasse, 

Could you please elaborate more on your CC1310 code? To be more precise, could you include I2C params used as well as the definition of "I2CtransactionStruct" as well as what "Transaction" in I2C_transfer(i2c, Transaction) is.

I would assume "Transaction" to read "i2cTransaction". I'm not sure I understand your architecture with the "commStruct" and how it works in the bigger picture. To give any good feedback to why it seems like you are stretching the clock I would need to know all details about your custom build up. If you do not want to share it here, feel free to reach out to me in PM.