We're trying to figure out what makes the green LEDs on the grbl shield light up, flicker, and/or turn off. One or more of them seem to change state when we open or close the USB port, but other than that, we can't see a particular pattern to the change(s). What do these LEDs signify?
Green LEDs
From the original Synthetos forum (2011–2025)
The green LEDs are just an indicator of stepper driver activity. Electrically they are just the voltage on phase A1 with respect to ground. This means that if the driver chips are activated or changing this phase may change. Since grbl asserts ENABLE to all chips they tend to all go on when grbl is activated.
Mostly the LEDs are there to provide an indication that the motors are running and working. It's useful for diagnostics to see if grbl is talking to the board, and to see if the drivers are working even if the motors are not (mis-wired, disconnected, blown, etc.)
This topic is from the original forum (January 2014). Your reply starts a new discussion linked to it.
Back to grblShield Support or latest activity.