RTC goes slow - three min within a day

Hello community,

I have the problem that the clock of my bangle.js 2 goes wrong after a short period of time.
The device has the 2v17 firmware (But it was already a problem in previous versions).
Is this a general issue the bangle has or a hardware problem (or a software problem making the RTC chip lose track of time)?
Since I (still) have an iPhone, synchronizing the time via Gadgetbridge - as I read it somewhere in the forum - is not a fix.
For now, I set the time manually by connecting it to the AppLoader every time...

Hi!

If you haven't, try using the 'Adjust Clock' widget.

It has been suggested to have it work the drift out automatically using GPS.

Hi! To be honest, I also have a big problems with this lately. As far as I understand, time drift appears due to the fact that I often use timers and stopwatches running in the background for a long time. I tried to fix the problem using the Adjust Clock app, but it's still an approximate solution and the time goes astray.

It would be great to have accurate RTC on a consistent basis.

Hi, sorry to hear this - so you're saying that the Bangle loses three minutes every day? Has it always done this, or did it only happen recently?

The Bangle itself has a hardware RTC inside which keeps track of time with its own external low speed oscillator. This should be rated to around 20ppm (parts per million - I'm checking with the manufacturer now) which should put the expected time loss at under 2 seconds per day.

There's a very small chance that the Bangle could be missing RTC 'rollovers' but otherwise the only other issue could be some problem with the RTC oscillator itself.

I've just uploaded a new firmware (to this post) and maybe you could try that? It will disable the low speed oscillator and will instead use an internal oscillator, which is calibrated from the high speed oscillator. While not quite as accurate, it's not bad at all and it would be very interesting to see if that fixed your problems.

As far as I understand, time drift appears due to the fact that I often use timers and stopwatches running in the background

I really don't think this should be an issue - timekeeping is handled at a much lower level than that, so apps you have installed should have no effect (apart from the Adjust Clock which does mess with the time).

If you do manage to reproduce this reliably please let me know what steps are required though!

1 Attachment

• espruino_2v17.25_banglejs2.zip

Hey!
Sorry for the late answer. I got a few more problems with the watch, but after reinstalling all apps it got way better, also with the time problem.
Without measuring, it's more a second than a minute delay in the meantime, so I did not try out your firmware, but I will keep an eye on the time closely.
I've got one more question: is the RTC influenced by turning the bangle off at night?

I've got one more question: is the RTC influenced by turning the bangle off at night?

Yes, it would be. I think after a reboot the RTC gets completely reset and Bangle.js has to reconstruct the time based on what it was at the last RTC 'tick', so it may well lose some time there.

Personally I never bother turning it off - if it's not moving it goes into a low power mode, and assuming your watch face doesn't use a bunch of power they can last for well over a month,