@AnalysIR, once the new firmware rolls out I will be working on an entirely new SparkIntervalTimer library which will support all timer modes, including PWM, output capture (used by Tone for example), input capture and straight timer interrupts. The catch with the PWM pins is that they are channels of a common timer so changing that base timer will affect all of its channels as well. I have started a topic on this development and @maghis will be contributing. You are more than welcome to contribute as well 