Halcogen I2C driver not detecting missing slave?

Thomas,

I've contacted the Halcogen team to ask them to have a look to your problem.

Hi,
Checkout my post on this issue: e2e.ti.com/.../394139

At the end of the day the silicon can't detect when a slave does not ACK during its addressing phase, so you have to check for a NACK on the first data byte and ignore any checks during the addressing phase.

Cheers
Stomp!

Hi

Please try  christian suggestion in the post and let us know if you still need some help

Hi,

the missing slave problem is solved with ignoring NAK's on slave addressing.

But now the Arbitration loss problem occured.

The Halcogen driver also does not handles this problem.
Any suggestions?

Regards
Thomas

Hi Thomas,

Not sure what you mean with Arbitration Loss problem.

Please have a look at SPRU175. I find, that this document is very helpful when it comes to implementing a I2C driver for the HW module used on Hercules.

As per description in SPRU175 arbitration loss means, that two masters tried to transmit at the same time. I would guess that a way to handle this is to retry transmission after a certain time, like it is done in the CAN protocol. However, the I2C module can't resolve this by it's own.
To my mind this is an application defined behaviour and thus has to be handled in you I2C communication driver not in the HALCoGen low level routines.

Best Regards,
Christian

Hello Christian,

i am still investigating the problem.
So far I know, the problem occurs after switching the i2c multiplexer(PCA9544A) that have another i2c master on the secondary side, and the other master is talking to the slave when switching.

Do you have an example how to generate the repeated start condition for Halcogen?
Should I use i2cInit() before every single transmission?

Best Regards
Thomas

Hi Thomas,

The code that I posted here uses repeated start conditions to read multiple bytes from a slave.

    /* Transmit Repeated Start condition */

You don't need to call i2cInit before every transmission as long as the transmission was correctly terminated, which my code should do.

Best Regards,
Christian

Hi Thomas,

Have you tried/looked at the Example example_i2cMaster_TX_RX.c and example_i2cSlave_TX_RX.c that comes with HALCoGen 4.04.xx ? This is basically 2 board example in which one Hercules board acts as master which contains example_i2cMaster_TX_RX.c and other board example_i2cSlave_TX_RX.c is loaded and that acts as Slave.

Hello Prathap,

my code bases on the examples.
But there is also no repeated start example.

I have to write the control register address to a slave and a second master is writing an other address to the slave.

Hi Thomas,

HALCoGen 4.04.00 Example example_i2cMaster_TX_RX.c is a repeated Start example. For Start condition is set for every 10 Bytes of Data TX or RX. 

As per example

Master first does 2 * 10 bytes TX.
Master sets Start condition, does 10 Bytes of Data TX, Again sets Start condition, does 10 Bytes of Data TX.

Then Master does 2 * 10 bytes RX
Master sets Start condition, does 10 Bytes of Data RX, Again sets Start condition, does 10 Bytes of Data RX.

Probably I am not getting your problem exactly. If you have faced a Arbitration lost in your master, you must clear the flag and re initiate the transfer right from setting the Mode to master, stop bit, then start bit etc... like in the example file... 

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/* Set mode as Master */
i2cSetMode(i2cREG1, I2C_MASTER);

/* Set Stop after programmed Count */
i2cSetStop(i2cREG1);

/* Transmit Start Condition */
i2cSetStart(i2cREG1);

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