I need to add support for the UNO R4 (both models) for a library I'm maintaining. The library uses the LED on pin 13 as status indicator. I can't find any information whether that LED is still there on the R4 Minima and Wifi boards. The R4 Wifi has this nice LED matrix, so the other LED might be gone for it.

  • 2
    as always, it is LED_BUILTIN
    – Juraj
    Jul 24 at 5:00

1 Answer 1


The schematics for the R4 Minima and Wifi boards can be found at: https://docs.arduino.cc/resources/schematics/ABX00080-schematics.pdf and https://docs.arduino.cc/resources/schematics/ABX00087-schematics.pdf . Pin 13 is also labeled SCK. A LED is attached to this pin.

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