Encoder knob count limits how do i do it

Other Hardware Robotics
1

I'm using this code with an encoder that I'm using for a volume knob.

I want to only count between 1 and 300.

if I get to down to 1 or up to 300 it stops counting no matter how much i turn the knob.

thanks,


```cpp
enum PinAssignments {
encoderPinA = 3,
encoderPinB = 4,
clearButton = 8
};

volatile unsigned int encoderPos = 0;
unsigned int lastReportedPos = 1;

boolean A_set = false;
boolean B_set = false;

void setup() {

pinMode(encoderPinA, INPUT);
pinMode(encoderPinB, INPUT);
pinMode(clearButton, INPUT);
digitalWrite(encoderPinA, HIGH); // turn on pullup resistor
digitalWrite(encoderPinB, HIGH); // turn on pullup resistor
digitalWrite(clearButton, HIGH);

// encoder pin on interrupt 0 (pin 2)
attachInterrupt(0, doEncoderA, CHANGE);
// encoder pin on interrupt 1 (pin 3)
attachInterrupt(1, doEncoderB, CHANGE);

Serial.begin(9600);
}

void loop(){
if (lastReportedPos != encoderPos) {
Serial.print("Index:");
Serial.print(encoderPos, DEC);
Serial.println();
lastReportedPos = encoderPos;
}
if (digitalRead(clearButton) == LOW) {
encoderPos = 0;
}
}

// Interrupt on A changing state
void doEncoderA(){
// Test transition
A_set = digitalRead(encoderPinA) == HIGH;
// and adjust counter + if A leads B
encoderPos += (A_set != B_set) ? +1 : -1;
}

// Interrupt on B changing state
void doEncoderB(){
// Test transition
B_set = digitalRead(encoderPinB) == HIGH;
// and adjust counter + if B follows A
encoderPos += (A_set == B_set) ? +1 : -1;
}
2

if encoderPos is less than 1, encoderPos = 1
if encoderPos is greater than 300, encoderPos = 300

3

If you provide complete information as recommended by the forum,
(" How to get the best out of this forum),
you will have a better chance of getting help.

Post a schematic of your project;
Which Arduino are you using?
How your project should work.

BTW, if using UNO/Nano/Mini, the interrupt pin are 2 and 3.

Not 3 and 4.

 encoderPinA = 3,
  encoderPinB = 4,

 digitalWrite(encoderPinA, HIGH); // turn on pullup resistor
  digitalWrite(encoderPinB, HIGH); // turn on pullup resistor

PS:

Try this code:

enum PinAssignments {
  encoderPinA = 3,
  encoderPinB = 2,
  clearButton = 8
};

volatile unsigned int encoderPos = 1;
unsigned int lastReportedPos = 1;

boolean A_set = false;
boolean B_set = false;

void setup() {

  pinMode(encoderPinA, INPUT);
  pinMode(encoderPinB, INPUT);
  pinMode(clearButton, INPUT);
  digitalWrite(encoderPinA, HIGH); // turn on pullup resistor
  digitalWrite(encoderPinB, HIGH); // turn on pullup resistor
  digitalWrite(clearButton, HIGH);

  // encoder pin on interrupt 0 (pin 2)
  attachInterrupt(0, doEncoderA, CHANGE);
  // encoder pin on interrupt 1 (pin 3)
  attachInterrupt(1, doEncoderB, CHANGE);

  Serial.begin(9600);
}

void loop() {
  if (lastReportedPos != encoderPos) {
    Serial.print("Index:");
    Serial.print(encoderPos, DEC);
    Serial.println();
    lastReportedPos = encoderPos;
  }
  if (digitalRead(clearButton) == LOW) {
    encoderPos = 1;
  }
}

// Interrupt on A changing state
void doEncoderA() {
  // Test transition
  A_set = digitalRead(encoderPinA) == HIGH;
  // and adjust counter + if A leads B
  encoderPos += (A_set != B_set) ? +1 : -1;
  if(encoderPos < 1) encoderPos = 300;
}

// Interrupt on B changing state
void doEncoderB() {
  // Test transition
  B_set = digitalRead(encoderPinB) == HIGH;
  // and adjust counter + if B follows A
  encoderPos += (A_set == B_set) ? +1 : -1;
  if(encoderPos > 300) encoderPos = 1;
}
4

that works great
but

the 1 or 300 it needs to stop counting and not roll over.

for example

if I get to 300 and keep turning the knob up it stays at 300.
and doesn't roll over to 1

if I get to 1 and keep turning the knob down it stays at 1 and doesn't roll over to 300

6

Just modify these lines.

if(encoderPos < 1) encoderPos = 1

if(encoderPos > 300) encoderPos = 300;
7

Try

`encoderPos = constrain(encoderPos+(A_set != B_set ? +1 : -1));

Or
encoderPos = min(300, max(1,encoderPos+(A_set != B_set ? +1 : -1)))

8

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