No HRM / ECG readings

[DanielDecker]

I have my Bangle.js 2 since 3 months. The HRM interval in the health app is configured to 10min. A few days ago it stopped showing heart rates in the middle of the day. Since then, I haven't been able to get any HRM readings from the watch, neither after the 10min interval nor with a manual measurement using the Heart Rate Monitor app. In the Heart Rate Monitor app I get only a straight red bar which stops after a few seconds, just like the light sensor delivers no readings and goes to idle (see picture below).

My Bangle.js 2 runs with firmware version 2v29 (git 6106910), HRM app is version 0.13.
Restarting the watch did not help. I also tried the edge firmware with no success.

Has anyone experienced the same problem? Is there a way to revive my HRM?

[gfwilliams]

Sorry you're having trouble. I haven't come across this kind of problem before.

I see you've installed a few other apps/widgets - you don't have anything like Bluetooth Heart Rate Monitor installed do you that might be attempting to override the built-in heart rate monitor?

You could do a backup of your watch via the app loader, then do a factory reset, install the heart rate app again and see if it behaves any differerently? You can always restore from the backup after to return it to the way it was.

Otherwise I have to ask: have you been swimming/bathing/showering with it? While it's meant to survive quick/accidental submersion, it's not meant for repeated or long periods underwater, and if water has got inside it's possible it might have caused the HRM to fail.

[DanielDecker]

Thanks for your fast answer!
No, I haven't installed Bluetooth Heart Rate Monitor. I did a factory reset as you have described and tried the HRM again. Sadly the result is the same as mentioned above. The red rectangle shows no change in intensity at all. And stops before reaching the middle of the screen.

I'm aware of these limitations and take the watch off when swimming/bathing/showering. In Germany it is currently quite hot. When cycling I sweat a lot. I guess the watch doesn't care about skin covered in sweat.
I'd like to test older firmware with the watch, one with the open source HRM algorithm. What version can you recommend?

[gfwilliams]

Thanks for trying that out! The HRM algorithm applies to the data that comes out the sensor (the red line) so even swapping to an old firmware wouldn't help as the issue seems to be at a lower level.

The watch is designed to deal with some wetness too, and sweat should be totally fine. It's just repeated/deep/long submersion that causes problems. If sweat had got into the HRM and caused issues that's something I'd want to replace the watch for.

If the issue really is the wear detection, we could try turning it off. Please can you connect with the Web IDE (https://www.espruino.com/ide/) using the button in the top left, then paste the following line in on the left-hand side and press enter.

require("Storage").write("hrmfix.boot.js","Bangle.setOptions({hrmWearDetect:false})");

The next time you swap apps it should load this code - and then at least the HRM app shouldn't stop working. I'd be interested to see if it works ok, or if it's still just outputting a flat signal that never varies (it can take a few seconds for it to adjust itself to get a reading properly)

Note: if you want you can remove the fix after just by deleting the file hrmfix.boot.js using the storage menu in the IDE, or by pasting in require("Storage").erase("hrmfix.boot.js")

[DanielDecker]

Thanks for the explanation and your support.

I executed the code in the webIDE. As expected the HRM continues without stopping. The following screenshot was taken after several seconds just before the red rectangle fills the screen.

Sadly the output is still a flat signal. As you can see I switched back you my original config (backup), which doesn't include the BT HRM app and showed a "noisy" output (red rectangle) before the problem occurred. Also I didn't change anything (apps, config) during the week the problem occurred.

[gfwilliams]

Ok, thanks for trying that. It looks like a hardware failure then - and it looks like you haven't had the Bangle for long.

Please can you send an email to contact@espruino.com with a link to this thread, where you ordered from, and your shipping address and we'll get a new Bangle sent out to you.