(Arduino) Is there a way to add a stopwatch to count how long the user has spent time using the program? - c++

Question

Our project is a mp3 player, we're all beginners at coding. The project has a sort of a 'main menu' from which the user is able to choose from options such as: show track info, shuffle playlist, etc. Now we're trying to add a feature that tells the user how long they've been logged in. Our stopwatch code:
unsigned long timeListened = 0;
static int sknt1=0;
static int sknt10=0;
static int min1=0;
static int min10=0;
static int hour1=0;
static int hour10=0;
static int hour100=0;
void loop() {
timeListened = millis();
if (timeListened >= 1000) {
sknt1 = sknt1 + 1;
timeListened = 0;
}
if (sknt1 == 10) {
sknt10 = sknt10 + 1 ;
sknt1 = 0;
}
if (sknt10 == 6) {
min1 = min1 + 1;
sknt10 = 0;
}
if (min1 == 10) {
min10 = min10 + 1;
min1=0;
}
if (min10 == 6) {
hour1=houri1+1;
min10=0;
}
if (hour1 == 10){
hour10 = hour10 + 1;
hour10=0;
}
Serial.print (hour100);
Serial.print (hour10); Serial.print(hour1); Serial.print(":");
Serial.print(min10); Serial.print(min1); Serial.print(":");
Serial.print(sknt10); Serial.println(sknt1);
delay(1000);
}
The issue is, we can't find the right spot to place this code in. Only results we've had is either the stopwatch adds 1 second every time the user chooses the option from the menu, or the stopwatch time is just 000:00:00.
Is there a way to make arduino run the stopwatch in the background while the main program (playing music) is running ?

Answer 1

I have written a some code that prints the elapsed time since the Arduino was turned on for another project. It is not efficient, but it works.
You could call this every second in your loop() in order to update it.
#define second (1000L)
#define minute (60L*1000L)
#define hour (60L*60L*1000L)
unsigned long testTime = millis();
unsigned long hh = (testTime ) / hour;
unsigned long mm = ((testTime ) % hour) / minute ;
unsigned long ss = (((testTime ) % hour) % minute) / second;
Serial.print(hh);Serial.print(':');
Serial.print(mm);Serial.print(':');
Serial.print(ss);Serial.print('\n');

Answer 2

You are already using millis in your code which gives you the time in milliseconds ellapsed since the program started.
So whenever you want to know how long the program has been running just call millis().
This will overflow after approximately 50 days but that's probably irrelevant in your use case.
The problem with your code is that you add 1 second every time millis returns a value > 1000 which is always the case if your Arduino is running for more than 1 second.
This also has the effect that you only add 1 second every time you check that. Not every second.
There is also no need to delay your program to get an update every second.
Simply conver the return value of millis() to a time string. It gives you the milliseconds since program start. So calculate how many hours, minutes and seconds that is. I guess I don't have to tell you that 60000ms make a minute...
If you want to know the time passed since a certain event. For example a user login, you store the time of that event and calculate the difference to the current time.