Quote Originally Posted by Doddy View Post
Interrupt on change of state? Your time-sensitive processing is in the discrete control and not the I2C if you're using the TWI registers.
Yes it is possible you can register for toggle interrupts on any of the IO pins, trouble is my code is written in arduino/cpp at the moment, this means there is a stack to park so there is some overhead from servicing the interrupt. If the current polling approach takes too long will have a look.