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);
}