# Measuring .7 volts on pin 2 and 0.0 on the rest when setting all pins low

Having my Arduino Nano 328P disconnected from any circuitry and setting all pins to `pinMode(OUTPUT)` and writing `LOW` to (almost) all the pins, when I connect my multimeter to every output pin and the Arduino ground, I measure 0.7 volts on pin 2 and 0.0 volts on 3 to 19. Here I mean the pin numbers on the edge of the Nano, not the processor pins.

For my project it worked out fine because I needed those 0.0 and not the 0.7, but I'm afraid it suddenly might not be pin 2 that's 0.7 in the future and my circuit would fail.

Why is there this one pin giving 0.7 instead of 0.0 and how can I make sure or argue that it will only be pin 2 that gives 0.7?

EDIT as per request, the full test code is below.

``````void setup() {
for (int i=1;i<20;i++){
pinMode(i, OUTPUT);
}
}

void loop() {
for (int i=1;i<20;i++){
digitalWrite(i, HIGH);
}
delay(3000);
for (int i=1;i<20;i++){
digitalWrite(i, LOW);
}
delay(3000);
}
``````
• What voltage is your 328P running at? At 5V, 0.7V is still perfectly within specification (0.9V max V[OL]). Commented Oct 2, 2016 at 11:38
• @Majenko I'm not sure exactly, I'm running it via a phone wall adapter which outputs 5V/1A which I think should be enough, how could I check if it really is? If you think it's the voltage provided, I'll check when powering it via my laptop. Commented Oct 2, 2016 at 12:27
• No, you misunderstand. There are two options for running the boards like the Micro / Nano, etc - 5V or 3.3V. The V[OL] specification changes depending on supply voltage, and that is fixed by the board, not the PSU. It sounds like you have a 5V version anyway, so the output is within specification. Commented Oct 2, 2016 at 12:29
• @Majenko To summarize 660 pages into 444 seems weird to me, haha. atmel.com/Images/… Commented Oct 2, 2016 at 12:57
• @Majenko I think you should post your comments as one answer. Commented Oct 2, 2016 at 13:23