Arduino nano input of analog pin is always 1

[UKHeliBob]

@stitech

In if (R == HIGH) the compiler recognizes the right part as Boolean

But the right hand side is not boolean, it is 0x1

[stitech]

@UKHeliBob

not boolean, it is 0x1

It’s 0x1 after translation.

But now we’re nitpicking on terms.

The main issue for the OP is that he is comparing an analog measurement to something Boolean, which will not produce the result he hopes for.

[UKHeliBob]

@stitech

But now we’re nitpicking on terms.

It is not nitpicking to say that HIGH is not a boolean. A boolean is a data type, not just a value of 0 or 1

Whilst I agree that the use of analogRead() to test for HIGH makes no sense, what is being tested is not a boolean

[JohnLincoln]

@stitech

You are wrong about this, anything nonzero will be converted to HIGH.

Before I posted reply #16, I did a little test to verify that what I was saying was correct.

I modified gonanf_2's code to print out the value of 'R', as well as a message to say ', R == HIGH' if the condition (R == HIGH) was met.

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(A0, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:

  int R = analogRead(A0);
  Serial.print(R);
  Serial.print("");
  if (R == HIGH) {
    Serial.print(", R == HIGH");
  }
  Serial.println();
  delay(10);
}

and here are the results:

The message ', R == HIGH' is only printed when R = 1.

I won't bother showing the other 970 or so values of R that don't print the message ', R == HIGH'.

[alto777]

@JohnLincoln THX for going to the trouble.

tl;dr not a rant

I can understand someone posting wrong, even dangerously or stupidly wrong information.

Something you "learned", something that has always worked for you, something you see other ppl doing alla time.

Perhaps that can be excused.

But there is no excuse for doubling down, digging deeper the whole you've been told you were in, in some cases adding more bogus reasoning and "facts" when…

...in (I estimate) about eleven minutes you could just get out a stupid UNO board, write a twenty line program and demonstrate the correctness of your POV or show yourself your own ignorance.

And even less of an excuse these days, when you can shave minjtes off such an effort by using the wokwi simulator…

There are things I am so very sure about I can just post on the matter at hand. If someone sez "nah huh, you wrong", I don't respond "am not am not" until I have googled and maybe also done a little tiny test, takes eleven minutes or less.

When I am wrong, I don't mind saying so, and I appreciate the opportunity to learn something, which I can freely say I do here in these fora with some good regularity. I don't think I'd participate if I wasn't also learning something. About C/C++, about coding, about what ppl get up to with these little toys, about myself.

This is the nice thing about engineering and science. Experiments can test theories, and participants agree to abide by the results.

a7

[stitech]

I stand corrected.
I ran a little test myself, and (R == HIGH) evaluates to 1 only when R is 1, and 0, 2, 3, … 1023 all produce a 0.
Apparently “HIGH” is translated to 1 before the comparison, the compiler doesn’t recognize it as Boolean.
Still, it doesn't produce the result the OP probably hoped for.

[UKHeliBob]

@stitech

Apparently “HIGH” is translated to 1 before the comparison

Because of how HIGH is #defined

#define HIGH 0x1

a 1 is inserted into the code even before it is compiled