I came back to an arduino uno i had and i tried to write some basic code. I used the most basic debugging program for analogue read from the docs
int analogPin = A3;
int val = 0;
void setup() {
Serial.begin(9600);
}
void loop() {
val = analogRead(analogPin);
Serial.println(val);
delay(200);
}
My pin is reading 1023 constantly. I connected it to ground via 10k resistor and still it reads 1023. I connected it directly to GND and still 1023. I tried it with all 6 pins A0~A5 and no luck.
I'd say it's blown. Grounding the input should make it read zero and that's how I would have tested it.
In my limited experiments I've seen the floating-unconnected input floating-around the mid-range. I never saw it "jammed" at zero or 1023.
But you'll never REALLY know until you replace the Arduino or otherwise solve the problem.
...It's unusual for a microcontroller to fail that way. Usually a processor will die completely and the code won't run. I'm not saying it's impossible.
To be honest the device is at least 5 years old. The last two years it was always on in a box in my balcony (automated watering system). Also it was sprayed with hot glue and then bathed with ethyl alcohol to remove the hot glue. There is a good chance it sustained some damage. I will buy a new one and I will test the program there. But the program is very simple I don't think it is a problem. Also the main chip is a little hot when idling
Grounding the input should make it read zero and that's how I would have tested it.