Program not working as expected

Thanks. I will modify my code.

Also, you need to code your bidirectional (or is it supposed to be a tri-state?)

It is open drain output with external pull up resistor and at the same time it is input. Not sure what category should I choose. CPLD should be able to read the line and at the same it should be able to set the line to 0 or high impedance.

Finally, you're doing an if check on start being 0, but then setting start to 0 as an action in that same if check. I'm not sure what you're trying to do.

I'm checking, if the MCU pulled start low and if so CPLD pulls the signal also low signalling that it started doing its job. MCU can then release that signal. Later (this is not visible in the code) CPLD sets the start signal to high impedance 'Z' (releasing the line) signalling that it finished the job. Start then goes 1 (as there is external pull up) and MCU detect rising edge which means CPLD finished its job.

Is it wrong?