Any experience with Slave I2C

[Gerd]

Hi everyone,

I'm seeing a I2C problem for the last couple of days.

I'm using 16f876 as master and 16f872 as slave processor. The ccs version is 3.180 and the Slave code is from Ex_slave.c

Now everything works fine on the workbench, I read analog data from the slave every 100ms. When I install it in a noisy (electrically) environmet communication stops aftre a few minutes.
The Master is still sending clock, but SDA is low, forever, Slave pulling it down.

I assum the Slave gets a spike, calls the interrupt routine and than gets no more data antill the master sends a new telegramm.

The processor is still doing the main loop, so it is not crashed.

I also can't get the I2C working again. Tried restart_cpu, SDA is low!

Any idea if it is a spike problem and how I can solve it. I don't mind if the I2C is looked for a few secunds, as long as I can detect the crash and restart it.


Slave code:

#INT_SSP
void ssp_interupt ()
{
BYTE incoming;

if (i2c_poll() == FALSE) {
if (fState == ADDRESS_READ) { //i2c_poll() returns false on the
i2c_write (buffer[address]);//interupt receiving the second
fState = NOTHING; //command byte for random read operation
}
}
else {
incoming = i2c_read();

if (fState == NOTHING){
fState = CONTROL_READ;
}
else if (fState == CONTROL_READ) {
address = incoming;
fState = ADDRESS_READ;
}
else if (fState == ADDRESS_READ) {
buffer[address] = incoming;
fState = NOTHING;
}
}
}

[PCM programmer]