Rotary encoder limits

Community General Discussion
1

Hello, all
I have a small code to have a analog output from arduino uno controlled by a rotary encoder.
that go from 0 to 255 now will I to limit it that it not go from 255 to 0 or from 0 to 255.
What do I wrong?! this is my code:

//Control LED Brightness with Rotary Encoder //

#include <RotaryEncoder.h>
#include <Encoder.h> //includes the Encoder Library
Encoder myEnc(6, 5);  // defines the Encoder object

//defining variables//
byte oldPosition = 0;
byte newPosition;
byte const led = 9;

void setup()
{
    Serial.begin(9600); // begins the serial monitor
    pinMode(led, OUTPUT); // sets the pinmode to output
}

void loop()
{
    newPosition = myEnc.read() / 4; // reads position of the encoder
    {
        if (newPosition != oldPosition)
            oldPosition = newPosition;
        //       Serial.println(newPosition);
        //       analogWrite(led, newPosition);

        if (newPosition > 255) // encoder max
            oldPosition = 255;

        else if (newPosition < 0) // encoder min
            oldPosition = 0;
    }
     Serial.println(newPosition);
     analogWrite(led, newPosition);    
}
2

Hello

A byte cannot be greater than 255 or less than 0.

1 Like
3

Change your test value to >= 254.

4

that is also the intention pwm of 8 bits.
but >= 254 does not help.
if I turn the encoder is go's from:
8
7
6
5
4
3
2
1
0
255
254
etc

or from
253
254
255
0
I want that it limit from 0 to 255 also wen I turn further

5

@pvdbos it's a bit too tricky to do exactly what you want just now.

But try feeding your 0..255 values to this logic.

// first let the encoder supply the number

newPosition = myEnc.read() / 4;

// later use some maths to make it into a trangle wave:

        int x = newPosition & 0xff;    // just a byte, please
        if (!(x & 0x80)) x <<= 1;
        else x = (255 - x) << 1;

The variable x will go from 0 to 255 and then down to 0 then back up as you turn, no matter which way you turn.

If you want it to take twice as many clicks, try (untested)

// first let the encoder supply the number

newPosition = myEnc.read() / 4;

// later use some maths to make it into a trangle wave:

        int x = newPosition & 0x1ff;    // just 9 bits
        if (x & 0x100) x = (511 - x) ;

I may have to amend that, can't test it just now. Tested. Works.

HTH

a7

6

Why include two encoder libraries?

7

Like this..

good luck.. ~q

8

Sorry I removed the #include <RotaryEncoder.h
and it's working also thanks

9

Alto777
I have tried your code but is not working for my.

void loop()
{
    newPosition = myEnc.read() / 4; // reads position of the encoder
    {
        int x = newPosition & 0xff;    // just a byte, please
        if (!(x & 0x80)) x <<= 1;
        else x = (255 - x) << 1;
    }
     Serial.println(newPosition);
     analogWrite(led, newPosition);    
}

I will only to limit the encode as a potentiometer min and max value 0 to 255

10

Give it a fair chance. You don't seem to be reading the code to notice you bungled using it in any effective way.

The if/else statement transforms the encoder reading into a new variable. Use the new variable for printing and setting the LED brightness, viz:

void loop()
{
  newPosition = myEnc.read() / 4;

  int x = newPosition & 0xff;    // just a byte, please
  if (!(x & 0x80)) x <<= 1;
  else x = (255 - x) << 1;

  Serial.println(x);
  analogWrite(led, x);     
}

HTH

a7

11

Alto777
It work now but is it posible that when it is 255 and I turn further on the encoder that it stay on 255
and also with when it go's to 0 that it stay on 0

12

Alto777
What I want is to make a adjustable power supply to control from 0 to 50 volt and 0 to 10 amp
controlled by an Arduino variable with rotary encoder and some buttons .
so pwm signal 8, 9, 10, or 16 bits to change the volt and amp.

13

@pvdbos - sry for the sidetrack. Your description was misinterpreted.

Please look at the example here:

In your original, you made the same mistake as when you tried my code. You failed to use the constrained value which was oldPosition.

But that would have other problems anyway, so check the example I linked. Read it, figure it out.

a7

14

alto777
Hello, this is what I'm looking for, A RotaryEncoder with limits.
Thanks

15

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