PWM control not working

[paullarson]

Maybe this will help. It’s something I put together quite a while ago.

@paullarson

you can check the output by measuring its voltage with a multimeter. You will get different results if you measure DC vs AC, but you can still tell.

The output is a PWM signal (Pulse Width Modulation). The signal ranges from about 0V to 5V. Off would be 0V and full on would be a steady voltage close to 5V. For intensities in between the signal will be a series of pulses. At low intensities the pulses will be more off than on (lower duty cycle) and at higher intensities the pulses will be more on than off (higher duty cycles). Off = 0V and on = ~5V.

Here’s an example of PWM.

I made the following measurements (note $31 in the table should be $30):

Essentially you are just looking for change on the outputs with a a change in power %. The GRBL “s” commands control the intensity as shown in the chart. In my case I have max spindle speed set to 1000 ($30=1000).