Bangle.js 2 Cutting Edge - new heart rate algorithm

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  • Either you managed to scratch the glass or the protector is still on. If I remember correctly it had no tab or something like that to pull it off. On my first Bangle I thought I had received a scratched one and only a few days later I discovered it to be a protector. It was a tiny bit "frosted". Without the protector you should have a mirror finish just like the display glass has.

    Edit: @adjtm hehe, you ninjaed my post very closely :D

  • Here is video recorded, exactly 60 seconds, reported HR is 57-61 but if you count all the beats drawn it is actually 70

    Also I tried Cardiograph android app­ls? on my phone and it matches what my other watches/fitness trackers show. I disabled network before starting it as some people in reviews claim that showing ads make it less relible. For me it worked pretty well with no ads shown.

  • I just tried, and they are identical for me - more or less. The Bangle.js one moves around a bit more (I guess it'd not filtered) but they were within 1 bpm after a while.

    is it possible that the proprietary firmware for VC31 and VC31B should be different?

    I don't believe so, no... the distribution I had seems to deal with both models.

    I'm not really sure what to suggest... I mean you could try setting the heart rate period down so it's at 12.5hz with Bangle.setOptions - but it seems really strange to me that it seems to work well for me and others but not you.

    You don't have any apps installed that might be adjusting the time on your Bangle.js while the HRM is running do you?

  • OK, good that it works for you, did you try same HR monitoring app - the one that draws continuously (if that could perhaps slow it down)?

    I have nothing special there, the clock showing time is OK, it does not go faster or slower. Will try to remove all apps.

  • you could try setting the heart rate period down so it's at 12.5hz with Bangle.setOptions

    How would I do that? That is not described here­gle_setOptions
    my hrmPollInterval option is 40

    I set it to 2o and the monitor was drawing much faster but the HR is still off by same fraction
    Also I updated to latest 2.17.118, no change.

    Anyway, if it is not a common issue that others see too then don't bother.

    I did factory reset, then installed just heart rate monitor app on top of that and it behaves still the same.

  • Funny thing, I downgraded to 2.17 release to get back the older open source HR code and that one is correct! When confidence is 100 it basically shows same numbers as my other watches.

  • Hmm, well that's interesting then - I guess at least we know it's not hardware then.

    I know you tried hrmPollInterval with 20 - did you try it with 80? The HRM algorithm expects data to come in more slowly and I wonder if sending it data too quickly is actually impacting its accuracy (although as I say, it seemed to work ok for me and at least also when those graphs were made).

    I'm not actually 100% sure if I used the HRM app or not. As I understand the HRM should be done in an interrupt so it wouldn't matter, but I guess you could try using a Clock face with ClockInfo and then switching to the HRM clockinfo.

    ... or just reading the value in code with Bangle.on('HRM',print);Bangle.setHRMPowe­r(1)

  • I know you tried hrmPollInterval with 20 - did you try it with 80?

    With 80 the confidence almost never reach 100% and is overall much worse so the heart rate is more random and it does not look like it has any effect on this. With this I've seen it even 'stabilize' on numbers over 110 while fitness tracker was showing below 90 but I also saw cases when it gave similar numbers like with poll interval 40 (too low)


    I tried this with hrmPollInterval back to 40 and 2v17.120 and it makes no difference when compared to running Heart Rate Monitor (v0.11), still about 8-12 less than what my fitness tracker says or what can I count myself on the visible data coming from Heart Rate Monitor (v0.11) when I start it.

    I just retried again to switch between 80 and 40 with logging in IDE, see attached file. According to my fitness tracker my HR was about 76

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Bangle.js 2 Cutting Edge - new heart rate algorithm

Posted by Avatar for Gordon @Gordon