Could your clock frequency be off? Make a blink sketch with a really long delay, like 20 minutes, and time it with a stopwatch as accurately as you can. An error of <4% is usually ok, but tolerances vary.
Could your clock frequency be off? Make a blink sketch with a really long delay, like 20 minutes, and time it with a stopwatch as accurately as you can. An error of <4% is usually ok, but tolerances vary.