how to constrain value?

Projects Programming
1

if (-25<humidity_result<125){
humidity_r = humidity_result;
} else{
while ((humidity_result < -25) || (humidity_result > 125)){
delay(500);
humidity_result = humidity(temperatureC);
}
humidity_r = humidity_result;
}

Being humidity, it should be between zero and 100. I gave it some extra breathing room.

The first 2 readings I get on reboot are in the neighborhoods of 744% the first read, -6200% the second read, then third read is the correct 43%.

I applied the above code, and it didn't fix it.

Are bytes getting lost in the wireless transfer of data, or did my code just not fix anything?

2

You could use the constrain function

3

AWOL:
You could use the constrain function

Of course that would exist. What doesn't exist in C/Arduino? (sarcasm, don't answer that)

http://www.arduino.cc/en/Reference/Constrain

Ok, so how would I tell it to call the function again? the same if statement I already have, but looking for a and b? Or just the while loop?

4

it doesnt matter how long I wait. Whether I query the arduino twice immediately after restart, or if I wait a few minutes then query it. Still get 744 followed by -6200. So am I losing bytes, does it take 2 reads for Timer1 to initialize, or...?

Using FreqCounter library.

5

I don't understand what you're trying to achieve, but I very much doubt the first line of your code does what you intend:

if (-25<humidity_result<125)

I suspect you intend this to return true when humidity_result is greater than -15 and less that +125. It won't. It will be evaluated as two expressions. The first expression will be (25 < humidity_result), which will produce a boolean value. The second expression will be (boolean < 125), which will always be true since booleans are represented by int values 0 and 1 which are both less than 125.

If you want to check that the value is within a range, you need two expressions, for example:

if((humidity_result > -25) && (humidity_result < 125))
6

if (-25<humidity_result<125)

The if will result (nearly) allways in true: humidity is something between 0 and 100% (normally, but I can't see your whole sketch from here)

  1. -25< humidity_result will return true or false (0 or 1) which are both smaller than 125 ==> true

  2. humidity_result<125 will return in true (1) which is bigger than -25 ==> true

You could replace the block with only the while part

while ((humidity_result < -25) || (humidity_result > 125))
{
  delay(500);     // assuming this is needed for the sensor?
  humidity_result = humidity(temperatureC);  // is temperatureC constant or changing ???
}
humidity_r = humidity_result;
7

Thanks everyone. Didn't know that's how things were operated upon (I was indeed assuming literal). Rob's code worked right out of the box :slight_smile: