PWM pins on ATTiny841

Just like the good doctor told you back in post #4, you'll also need to program those pesky registers. You might have to stare at them for a while. I did. You can either modify them in your program or edit wiring.c. In either case, just recompile your sketch and whatever you edited in the core will also get recompiled.

You do know, of course, that the I2C hardware is for slave only. If you want your 841 to be an I2C master then it is done with a software I2C library and you can use any two pins.

Oh, crap - I think you can only get 5 PWMs with hardware I2C, because it's TOCC3 and 5 that you lose, but odd TOCC's can only be on output channel B, and even on channel A, so you only have 2 pins that can output channel B. Could use software I2C implementation though.

Hmm, seems to me that software I2C would be the answer for me. I'd like to keep as many pwm pins as I can, but still have the option to implement I2C if needed.

My board design is such that up to 3 identical boards can be used together and I2C would allow synchronisation of board activities. If software I2C would allow that, then keeping the pin allocations as allocated by DrAzzy's core would be fine as I could use pins 8 and 9 for I2C and have one board as master. Does that sound right?

Cheers :) Bernie