My Uno leaks power on the digital pins!!!


I got 2 unos one r3 and one older. Both leaks power, say I set digi pin 12 out or any not pwm pin low. The results is 1.5-2.5 v!!! And when high 3.8-4.2 roughly.
So when using led they behaviour is really odd.
Why sensitive is the bord to esd?
Have I broken some thing?

New calibrated Oscilloscope was used to measure the voltage.

Logic level HIGH and LOW are not absolutely 5v and 0v. Especially when measured with a high input oscilloscope.

Please describe your odd behaviour.


That's a new thing for me. I am used to work with plc.
If u start arduino ide
file> examples>02 digital>button
And use that code.
Check the voltage while o hold the button down 13 and gnd 0.53v
After release a peak comes at like 2.70-2.98 v
If I change the code from const int ledPin = 13; to const int ledPin = 12; when measuring ill get
10m volt when pushing the button (fast) and now pin 13 should be dead but it works just as before

i am finding this odd

Have you taken into account that there is a LED attached to pin 13?


Many of the cheap clone Arduino's have the LED connected directly to pin 13. (The official Uno buffers it with an opamp)

ther is no external led. voltege meater straight down in the pin. they are all 3 official unos.
one of the bordes is brand new alway handeld with anti-esd band