I am stuck with a problem which uses 50% duty cycle in timer1 and I need to increment the frequency by 100hz everytime I press a button. I am using the debounce for the button press. I thought I had to divide OCR1A by 2 but it is not the case.
/*
Debounce
Each time the input pin goes from LOW to HIGH (e.g. because of a push-button
press), the output pin is toggled from LOW to HIGH or HIGH to LOW. There's a
minimum delay between toggles to debounce the circuit (i.e. to ignore noise).
The circuit:
- LED attached from pin 13 to ground
- pushbutton attached from pin 2 to +5V
- 10 kilohm resistor attached from pin 2 to ground
- Note: On most Arduino boards, there is already an LED on the board connected
to pin 13, so you don't need any extra components for this example.
created 21 Nov 2006
by David A. Mellis
modified 30 Aug 2011
by Limor Fried
modified 28 Dec 2012
by Mike Walters
modified 30 Aug 2016
by Arturo Guadalupi
This example code is in the public domain.
http://www.arduino.cc/en/Tutorial/Debounce
*/
#define LEDPIN 3
float highTime;
float lowTime;
int freq;
float period;
//uint16_t val2= pulseIn(4, HIGH);
ISR(TIMER1_COMPA_vect) {
digitalWrite(LEDPIN, !digitalRead(LEDPIN));
}
// constants won't change. They're used here to set pin numbers:
const int buttonPin = 5; // the number of the pushbutton pin
//const int ledPin = 13; // the number of the LED pin
// Variables will change:
int ledState = HIGH; // the current state of the output pin
int buttonState; // the current reading from the input pin
int lastButtonState = LOW; // the previous reading from the input pin
// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastDebounceTime = 0; // the last time the output pin was toggled
unsigned long debounceDelay = 50; // the debounce time; increase if the output flickers
void setup() {
Serial.begin(9600);
pinMode(buttonPin, INPUT_PULLUP);
//pinMode(ledPin, OUTPUT);
// set initial LED state
//digitalWrite(ledPin, ledState);
pinMode(LEDPIN, OUTPUT);
// initialize Timer1 (the 16-bit timer) using channel A output compare
TCCR1A = 0; // set entire TCCR1A register to 0
TCCR1B = 0; // same for TCCR1B
TCNT1 = 0; // initialize counter value to 0
// set compare match register for 100 Hz increments
OCR1A = 9999; // = 16000000 / (8 * 100) - 1 (must be <65536)
// turn on CTC mode
TCCR1B |= (1 << WGM12);
// Set CS12, CS11 and CS10 bits for 8 prescaler
TCCR1B |= (0 << CS12) | (1 << CS11) | (0 << CS10);
// enable timer compare interrupt
TIMSK1 |= (1 << OCIE1A);
sei(); // allow interrupts
interrupts(); // enable global interrupts:
}
void loop() {
// read the state of the switch into a local variable:
int reading = digitalRead(buttonPin);
highTime = (pulseIn(4, HIGH));
lowTime = (pulseIn(4, LOW));
period = highTime + lowTime;
freq = 1000000 / period; //getting frequency with totalTime is in Micro seconds
Serial.print(freq);
Serial.print("\n");
delay(1000);
// check to see if you just pressed the button
// (i.e. the input went from LOW to HIGH), and you've waited long enough
// since the last press to ignore any noise:
// If the switch changed, due to noise or pressing:
if (reading != lastButtonState) {
// reset the debouncing timer
lastDebounceTime = millis();
}
if ((millis() - lastDebounceTime) > debounceDelay) {
// whatever the reading is at, it's been there for longer than the debounce
// delay, so take it as the actual current state:
// if the button state has changed:
if (reading != buttonState) {
buttonState = reading;
// only toggle the LED if the new button state is HIGH
if (buttonState == HIGH) {
highTime = (pulseIn(4, HIGH));
lowTime = (pulseIn(4, LOW));
period = highTime + lowTime;
freq = 4000000 / period; //getting frequency with totalTime is in Micro seconds
Serial.print(freq);
delay(10);
}
}
}
// save the reading. Next time through the loop, it'll be the lastButtonState:
lastButtonState = reading;
}