C++ Delay() in Timer: how to use correctly? - c++

Question

I'm a first semester software student and for a course I am exploring the world of C++ and Arduino (UNO in my case).
My assignment is to make a timer counting down from 10 minutes (shown on a 4 digit display).
The thing I struggled with is how to program a pause functionality on the same button (btnOne) that also starts the timer. When I finally discovered how, I noticed something buggy: the delay() might be causing some trouble. See my code for implementation.
When clicking on the start/pause button the button doesn't immediately register it. Possibly because the delay might be blocking the communication of user input to the button.
The delay (of 1 second) is used to limit the execution of the if-statement in timer() to once per second; like a timer.
My question is: how can I improve my code so that the clicks on btnOne are immediately registered?
Thanks so much in advance.
const int btnOne = 8;
const int btnTwo = 9;
int btnOn = LOW;
int btnOff = HIGH;
const int clockPin = 10;
const int dataPin = 11;
const int buzzer = 3;
int btnOneState = 0;
int btnTwoState = 0;
long time = 600000;
long timeValueState = time;
int timerDisplay = 1000;
bool pause = true;
void setup()
{
Serial.begin(9600);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
pinMode(btnOne, INPUT_PULLUP);
pinMode(btnTwo, INPUT_PULLUP);
pinMode(buzzer, OUTPUT);
}
void timer() {
// Count down from 600000 to 0
if (timeValueState >= 600 ) {
timeValueState = timeValueState - 600;
Display.show(--timerDisplay);
// When reached last count, display is set to 0 and buzzer turns on for 5 seconds
if (timeValueState == 600) {
Display.show(timerDisplay == 0);
tone(buzzer, 200);
delay(5000);
noTone(buzzer);
}
Serial.println("time:");
Serial.println(timeValueState);
delay(1000);
}
}
void loop()
{
btnOneState = digitalRead(btnOne);
btnTwoState = digitalRead(btnTwo);
// If button is on, change state of pause (true, false)
if (btnOneState == btnOn) {
Serial.println("btnOne pressed");
pause = !pause;
}
// When button is off and pause is not true, activate the timer
else if (btnOneState == btnOff && pause == false) {
Serial.println("btnOne NOT pressed");
timer();
}
// Reset time and timerDisplay back to 10 minutes.
if (btnTwoState == btnOn) {
Serial.println("btnTwo pressed");
timeValueState = time;
Display.show(timerDisplay = 1000);
}
}

Answer 1

I won't give you code so you learn more.
You can run a loop that checks the return value of millis vs a timestamp stored in a variable, when you started. Every 1000 milliseconds you update your display.
That way you don't block your code for 1 second.
This should serve as a good starting point for further research.