We want to create a constantly changing painting. Photoluminescent canvas become a perfect canvas for it, for you don't need an eraser for the machine to redraw the painting. Ideally the machine should look like a frame hanging on the wall.

the z axis has to be able to turn on and off to skip drawing the jogging tool path

the solution is directly reading from the motor control of z axis. Once a pulse is detected by a seperate microcontroller, it will be treated as a toggle to turn the uv flashlight on.

the tricky part is to read the high current input from the motor controller. One is dealing with the high current, the other is the bouncing. Bouncing is avoided by adding smoothing and delay. Resistors is added to the microcontroller input pin to reduce the current.

Another tricky thing I found out that you have to make sure that z axis is only turned on when it supposed to move. The default option is to turn all axis on while any of them is moving. That option will effect the readings and add potiential risk that light will turned on or off when x or y axis star to move.

It works out pretty fine after a long dreadful tuning. The microcontroller report the default state reading, last and current reading and its state everytime it get toggled.