TeensyCounter.ino

#include <avr/io.h>
#include <avr/interrupt.h>

const int upDown = 32;
volatile long counter = 0;
volatile long counter_buffer = 0;
volatile bool lockBuffer = false;

int ledPin = 13;

//#define HWSERIAL Serial1
// the setup() method runs once, when the sketch starts


void setup() {
  // initialize the digital pin as an output.
  pinMode(ledPin, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(33), myInterrupt, FALLING);
  pinMode(upDown, INPUT);
  Serial.begin(9600);
  //HWSERIAL.begin(9600);
}

// the loop() methor runs over and over again,
// as long as the board has power

void loop() {
  digitalWrite(ledPin, HIGH);   // set the LED on
  delay(10);                  // wait for a second
  digitalWrite(ledPin, LOW);    // set the LED off
  delay(10);                  // wait for a second
  //cli();
  //count_copy = overflow_count;
  //sei();
  lockBuffer = true;
  Serial.println(counter_buffer);
  //HWSERIAL.print(counter_buffer);
  lockBuffer = false;
  delay(10);
}

void myInterrupt() {
  int val = 0;
  val = digitalRead(upDown);
  if (val == 1) {
    counter += 1;
  }
  else {
    counter -= 1;
  }
  
  if (lockBuffer == false) {
    counter_buffer = counter;  
  }
  
}