Laser turns on during homing and axis movement – GRBL 1.1h + CNC Shield v3

[milad106]

Hi everyone, I’m using GRBL 1.1h on an Arduino Uno with a CNC Shield v3. My setup includes:

3 motors:

    X-axis connected to X driver

    Y-axis split across two motors: one connected to Y, the other to A

Laser connected to PWM pin D11

The issue I’m facing is that the laser turns on during homing and when jogging the axes manually. It only turns off when the machine reaches the home position or stops moving. I’ve already enabled laser mode using: $32=1. But even before running any G-code, the laser activates during homing or jogging. Even when I disconnect the PWM wire from the laser module, the laser still turns on during axis movement.

Has anyone experienced this? Is there a way to prevent the laser from firing during non-engraving moves?

Thanks in advance!

[bobbybumfluff]

Looks like inductive interference from motor wiring, to me. Is It possible to wire up laser to it's own power supply, with wiring well away from actuator motor wiring, to test. If you have a scope, look at the power rails, while moving, to see if it's power born interference. Additional capacitor/ inductive filtering could cure this. Try screened lead on the trigger of laser. The input of the trigger/pwm pin is a relatively high impedance. High levels of induced interference in this wire could trigger the laser. Also check for earth loops, in the wiring. It is always better to earth various components to a single earth point, radially, rather than in series, that is, like the spokes of a wheel.