getOxygenSaturationHistory returns outdated data

  function getOxygenSaturationData() {
    if (
      Toybox has :SensorHistory &&
      Toybox.SensorHistory has :getOxygenSaturationHistory
    ) {
      var iterator = Toybox.SensorHistory.getOxygenSaturationHistory({
        :period => 10,
      });
      var sample;
      for (var i = 0; i < 10; i++) {
        sample = iterator.next();
        if (sample != null && sample.data != null) {
          return sample.data.format("%2.1f");
        }
      }
    } else {
      return "N";
    }
    return "-";
  }

Sometimes the data will be outdated. e.g.

System widget tells 93

This function is 95.

What is the problem? Any idea is welcome

jim_m_58 over 3 years ago

This hasn't ever really worked on real devices since it was announced. Here's a bug report from a couple years back for example (and there are more)

https://forums.garmin.com/developer/connect-iq/i/bug-reports/toybox-sensorhistory-getoxygensaturationhistory-strange-samples

Last I checked, the data was always in oldest first order, yet the "when" for a sample was always newest first.

li2niu over 3 years ago in reply to jim_m_58

But some users told me other watchfaces are able to display the correct value like the value in the system widget. I didn't see the comparison pictures. Maybe I need more "real" clues after all pictures speak louder than words.

li2niu over 3 years ago in reply to jim_m_58

So I should read the last value of the sample? Thanks for your reminder.

jim_m_58 over 3 years ago in reply to li2niu

You can get the current value from Sensor, which you can do in a background service in a watch face. SensorHistory is the one that is "confused".

li2niu over 3 years ago in reply to jim_m_58

jim_m_58 said:
You can get the current value from Sensor

Sorry. I didn't get it. How can I get the current value of SPO2? Could you please elaborate on it?

jim_m_58 over 3 years ago in reply to li2niu

Sensor.getInfo().oxygenSaturation

In a watch face, you can only do this in a background service

li2niu over 3 years ago in reply to jim_m_58

Thanks. I found it. will it cost a lot to get the value synchronously?

ActivityMonitor.getInfo().oxygenSaturation;

If we get the value in a background service, which means the data will be updated at least per 5 minutes. Seems not in time

jim_m_58 over 3 years ago in reply to li2niu

Except it's not in ActivityMonitor:Info. I've not checked how often it changes in Sensor, but getting it every 5 minutes could be Okay (say it only changes every 5 minutes). When you get data from SensorHistory for things, it's often only saved every few minutes. Even for HR, last I checked a sample was only saved every 2 minutes or so, and that's something that's constantly changing.

li2niu over 3 years ago in reply to jim_m_58

OK. I don't know what the api do, does it just retreive the data from some cache area or take a detection synchronously?

Probably the former is the truth.

li2niu over 3 years ago in reply to jim_m_58

jim_m_58 said:
Except it's not in ActivityMonitor:Info.

OHHH. Sorry for my silly mistake