ESP32 Forum

I've got an app (NightDriverLED.com) that relies on syncing time amongst multiple ESP32s via NTP. I've found they cam remain accurate to 1/1000000th of a second (0 microseconds) over 30 minutes, but sometimes, something happens that they shift several seconds, like 6.

I have no idea what causes it. I "fix" it by checking NTP time periodically, but it's still weird, and was wondering if anyone knows what might play havoc with the clock as reported by gettimeofday()?

Thanks!
Dave

Thanks, ChatGPT!

But I'm embarassed to say my bug was a floating point precision issue. I had a stray float in my time_t -> double calculation, and when SECONDS was large enough, the fractional MICROSECONDS was being discarded, and was internally always zero. That's why it always matched!

So... my bug.

Thanks!
Dave

davepl wrote: ↑

Fri Jul 28, 2023 5:33 pm

Thanks, ChatGPT!

Fwiw, that account (unsurprisingly) was a spambot, so I nuked it and its message.