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The millis() and micros() both store the current time since the Arduino started, in an unsigned long variable. On 16 bits Arduino (Uno, Mega, etc), an unsigned long is stored on 4 bytes, or 32 bits. Values for the variable ranges from 0 to 4,294,967,295 (2^32 – 1).
18 sie 2021 · The micros() function reads the current counter value of Timer0 and calculates the elapsed time, because return value need even higher time resolution. Therefore, the execution time of the micros() function is considerably longer than millis() function.
18 lip 2014 · With millis() the time shown varies between 2 and 3 milliseconds. However if I change to micros(), the time shown is about 8700 micro seconds or 8.7 milli seconds. Can anyone explain why the big difference ?
The Arduino micros() & millis() functions, on the other hand, can be used to get and compare time stamps to achieve different timing requirements as per your application needs. And this has no negative impact on the overall system behavior or responsiveness.
So you can certainly call on millis() or micros() to find out the current time within your ISR, but don't expect that time to change. It is that lack of change in the time that is being warned about in the quote you provide. delay() relies on millis() changing to know how much time has passed.
13 maj 2024 · millis() is incremented (for 16 MHz AVR chips and some others) every 1.024 milliseconds, then incrementing by 2 (rather than 1) every 41 or 42 ticks, to pull it back into synch; thus some millis() values are skipped. For accurate timing over short intervals, consider using micros().
We mentioned one caveat with these functions, and that is that millis() and micros() overflow after around 50 days and 70 minutes, respectively. This potential issue can very easily be avoided with a small alteration to the code from last time.
