2.7 Test Extra I/O

Check List · Step 7 of 12 · Toggle the two spare outputs and watch their LEDs

🎯 Objective

This step checks the board's two spare output pins, GPIO.10 and GPIO.15 (the same pins used for flood and mist coolant). You'll switch them on and off with three simple commands and watch their indicator LEDs. No wiring and no multimeter needed.

V5.88 Ultra board showing the GPIO.10 / GPIO.15 indicator LEDs and the EXTRA IO header

The two spare-output LEDs (red circle) and the EXTRA IO header — GPIO.3 / GPIO.10 / GPIO.15 / GND. (click to enlarge)

🧪 How to Test

Open the FluidNC WebUI and type each command below into the command line. Watch the two LEDs circled in red on the photo.

M8 → The GPIO.10 LED turns ON (flood)

M7 → The GPIO.15 LED turns ON (mist)

M9 → Both LEDs turn OFF

✅ Pass: if both LEDs light up with M8 / M7 and go dark with M9, the spare I/O is working.

💡 Tip: these two pins are also broken out on the EXTRA IO header (next to GPIO.3 and GND), so you can use them for your own accessories later. GPIO.3 there is the tool-setter input — already checked back in step 2.5.

Step 7 of 12 2.8 Test MOSFET Output →