Difficult 3D carving project (Last supper)

[AndyC (Andy Corteen)]

I’m curious about this ‘eavesdrop the PWM line’ to provide a switch for an external system (such as a solenoid valve) and have some bits coming to experiment with making such a ‘switch’. Looking at using an ATTiny85 to synch (poor man’s PLL) onto the rising and secondly the falling edges of the PWM signal so such a solution could work with the two standard GRBL PWM frequencies (1.0KHz and 7.8KHz). Using the ATTiny would also permit a ‘up/down’ button user ability to choose which PWM threshold above which to ‘switch on’. It’s a bit of fun, but others may find the solution of interest…