bug in i2c driver for kinetis?

mastupristi — Wed, 12 Apr 2017 15:38:25 GMT

I'm refering to KSDK 2.2 for Kinetis K64

I you try to do an empty transfer the stop condition is never issued.

the case is:

    i2c_master_transfer_t masterXfer;

    masterXfer.slaveAddress = I2C_EEPROM_ADDRESS;
    masterXfer.direction = kI2C_Write;
    masterXfer.subaddress = 0;
    masterXfer.subaddressSize = 0;
    masterXfer.data = NULL;
    masterXfer.dataSize = 0;
    masterXfer.flags = kI2C_TransferDefaultFlag;

    I2C_MasterTransferBlocking(I2C0, &masterXfer);

this is useful to detect busy status of 24cXX i2c memories.

at the end of I2C_MasterTransferBlocking() funtion there is:

    /* Transmit data. */
    if ((xfer->direction == kI2C_Write) && (xfer->dataSize > 0))
    {
        /* Send Data. */
        result = I2C_MasterWriteBlocking(base, xfer->data, xfer->dataSize, xfer->flags);
    }

    /* Receive Data. */
    if ((xfer->direction == kI2C_Read) && (xfer->dataSize > 0))
    {
        result = I2C_MasterReadBlocking(base, xfer->data, xfer->dataSize, xfer->flags);
    }

    return result;
}

in case xfer->dataSize is zero there is no explicit or implicit call to I2C_MasterStop(), so I have solved adding this:

    /* Transmit data. */
    if ((xfer->direction == kI2C_Write) && (xfer->dataSize > 0))
    {
        /* Send Data. */
        result = I2C_MasterWriteBlocking(base, xfer->data, xfer->dataSize, xfer->flags);
    }

    /* Receive Data. */
    if ((xfer->direction == kI2C_Read) && (xfer->dataSize > 0))
    {
        result = I2C_MasterReadBlocking(base, xfer->data, xfer->dataSize, xfer->flags);
    }

    /* In case no data has to be transfer we have to send stop condition */
    if( 0 == xfer->dataSize )
    {
        result = I2C_MasterStop(base);
    }

    return result;
}

Can this patch be considered to be merge in the official source tree?

best regards

Re: bug in i2c driver for kinetis?

IvanRuiz — Wed, 19 Apr 2017 22:31:13 GMT

Hello, thank you for noticing this.

After a start condition has been sent and to prevent the bus to be left busy, there is a function which checks whether an arbitration lost has occurred and also checks for NAK:

/* Check if there's transfer error. */
result = I2C_CheckAndClearError(base, base->S);

If a NAK flag is detected, it will send the stop condition:

/* Return if error. */
if (result)
{
if (result == kStatus_I2C_Nak)
{
result = kStatus_I2C_Addr_Nak;

I2C_MasterStop(base);
}

So if no data has to be transferred, it will send a stop condition and the bus will no longer be busy.

Best regards,

Ivan Ruiz.

topic bug in i2c driver for kinetis? in Kinetis Software Development Kit

bug in i2c driver for kinetis?

Re: bug in i2c driver for kinetis?