how to creed very long times, 24 hours
Hedalen:
how to creed very long times, 24 hours
short numHours = 24;
Now, what was your real question?
You need to explain the context. Also what did you mean to type instead of "creed".
The Arduino's timekeeping is not good enough for long periods and you may need to get a Real Time Clock (RTC) module if you want to work with clock time.
...R
Robin2:
You need to explain the context. Also what did you mean to type instead of "creed".The Arduino's timekeeping is not good enough for long periods and you may need to get a Real Time Clock (RTC) module if you want to work with clock time.
...R
i ment to create a long waiting time, f.e. 24 hours
sorry for my bad English
Hedalen:
i ment to create a long waiting time, f.e. 24 hours
Do you plan to use an RTC module?
...R
Unsigned long can hold 86400000 milliseconds
surepic:
Unsigned long can hold 86400000 milliseconds
Punch 2^32 into your calculator for the correct answer.
I had a hard time inserting the "more than the needed" too. 
86400000 = 24 * 60 * 60 * 1000
And the "correct answer" is off by one.
@gfvalvo And what you got? Unsigned long can hold ~4.2billion. Milliseconds in a day 86.4million.
Isnt 86.4M going to fit in space with storage of 4.2B?
You could use a timer library, or simply:
const unsigned long oneDay = 86400000;
unsigned long lastRun = 0;
void doEvery24Hours()
{
//The code in this method will only be executed once every 24 hours.
}
void setup()
{
//Whatever
}
void loop()
{
unsigned long millisNow = millis();
if (millisNow - lastRun >= oneDay)
{
lastRun = millisNow;
doEvery24Hours();
}
}
Using a timer like TTimer from TDuino could be implemented as:
#include <TDuino.h>
const unsigned long oneDay = 86400000;
TTimer timer(timerCallback);
void timerCallback(byte timerId)
{
//The code in this method will only be executed once every 24 hours.
}
void setup()
{
timer.setup();
timer.set(oneDay, 0);
}
void loop()
{
timer.loop();
}
thank you all, gonna try first with the RTC
#define SECOND 1000L
#define MINUTE (60 * SECOND)
#define HOUR (60 * MINUTE)
#define DAY (24 * HOUR)
....
if (millis() - last_timestamp >= DAY)
{
last_timestamp += DAY ;
do_something ();
}