Ralph Doncaster

I may have to think about this a bit. One of the optimizations I did with ArdunoShrink is make millis() and micros() work without disabling interrupts. The fix means adding...

t0_fract is a negative value, so I think it should be (255 - t0_fract) * 4. https://github.com/nerdralph/ArduinoShrink/blob/master/src/t0_ovfl_isr.S#L38

Fix is not fully tested. It builds OK and the complied asm looks OK. Still needs testing on a live target.

What version of the Arduino IDE and what version of the SDfat library are you using? I haven't used the SDfat library, but I can try building it with and...