raw PPG sensor stopped working

Moderators: garrywadams, Aathif Mahir

Post Reply
no avatar
celina.chkroun
Posts: 1
Joined: Thu Apr 15, 2021 9:03 am
Cash on hand: Locked

raw PPG sensor stopped working

Post by celina.chkroun » Sat Apr 17, 2021 10:24 am

Good morning,
I am an Android developer owning a TicWatch Pro 3. I am trying to code an app doing continuous recording of raw PPG, accelerometer and gyroscope signals from the respective sensors on a 24h time window.

On this device, by reading the output of getSensorList(Sensor.TYPE_ALL), I have found out that the ID of the raw PPG sensor is 65572. In the first 4-5 weeks of testing my app on the Ticwatch Pro 3 I made small tests recording over only a couple of hours, and things worked fine, in the sense that I could get measures from all sensors for the whole duration of the test. During these tests, the PPG sensor at the back of the watch emitted a pulsating red/green light, exactly as the one produced when TicPulse when it measures the heart rate.

After that, I wanted to perform a test on 24h. My measures show that during the first 16 hours all sensors worked well, but after that the PPG stopped working. From that moment on, every time my app tried to use the PPG, the light emitted from the back of the watch was not the red/green pulsating light anymore, but rather a steady green light, but no measurement was received by my app. The diagnosis is as follows:

- at the beginning of my app's execution, right after the listener is set for the PPG sensor, the onSensorChanged method is called 83 times for the PPG, but after that, it is not called ever again inside my app, depite the green light still being on. However, if I launch a heart rate measure on TicPulse at the same time, the light still does not change (steady green light) but my app starts receiving the sensor events again, until TicPulse finished its measure and I stop getting events once again.

- if I launch TicPulse without my app being in use, the light emitted by the PPG sensor used is the red/green alternating light, but as said previously when my app accesses the PPG the steady green light appears. Nevertheless, even with the steady green light TicPulse is capable of obtaining a measure.

To try solving this issue I already tried resetting the watch 2 times, and following the suggestions on another post I also tried by rebooting the watch in shipping mode, however neither of these actions fixed the problem.

no avatar
kelly.maddy
Posts: 14
Joined: Tue Dec 08, 2020 5:37 pm
Cash on hand: Locked
Bank: Locked

Re: raw PPG sensor stopped working

Post by kelly.maddy » Wed Apr 21, 2021 1:19 pm

celina.chkroun wrote:
Sat Apr 17, 2021 10:24 am
Good morning,
I am an Android developer owning a TicWatch Pro 3. I am trying to code an app doing continuous recording of raw PPG, accelerometer and gyroscope signals from the respective sensors on a 24h time window.

On this device, by reading the output of getSensorList(Sensor.TYPE_ALL), I have found out that the ID of the raw PPG sensor is 65572. In the first 4-5 weeks of testing my app on the Ticwatch Pro 3 I made small tests recording over only a couple of hours, and things worked fine, in the sense that I could get measures from all sensors for the whole duration of the test. During these tests, the PPG sensor at the back of the watch emitted a pulsating red/green light, exactly as the one produced when TicPulse when it measures the heart rate.

After that, I wanted to perform a test on 24h. My measures show that during the first 16 hours all sensors worked well, but after that the PPG stopped working. From that moment on, every time my app tried to use the PPG, the light emitted from the back of the watch was not the red/green pulsating light anymore, but rather a steady green light, but no measurement was received by my app. The diagnosis is as follows:

- at the beginning of my app's execution, right after the listener is set for the PPG sensor, the onSensorChanged method is called 83 times for the PPG, but after that, it is not called ever again inside my app, depite the green light still being on. However, if I launch a heart rate measure on TicPulse at the same time, the light still does not change (steady green light) but my app starts receiving the sensor events again, until TicPulse finished its measure and I stop getting events once again.

- if I launch TicPulse without my app being in use, the light emitted by the PPG sensor used is the red/green alternating light, but as said previously when my app accesses the PPG the steady green light appears. Nevertheless, even with the steady green light TicPulse is capable of obtaining a measure.

To try solving this issue I already tried resetting the watch 2 times, and following the suggestions on another post I also tried by rebooting the watch in shipping mode, however neither of these actions fixed the problem.

Yes! Thankfully, now that a developer had chimed in with the issue, this is the same one that many customers have had with mobvoi refusing to replace the watches stating that it is water damage. However upon disassembly after them saying my warranty was not valid due to water I found that there was no water damage and it is actually a defective sensor or something else along those lines. Indicator wasn't tripped. I found after lengthy discharge and charging back up the sensors continually to work a relatively reliably. I'm updating to MR2 now to see if they have any background bug fixes that may have helped this.

no avatar
j.morin27
Posts: 2
Joined: Sat Mar 27, 2021 5:16 pm
Cash on hand: Locked

Re: raw PPG sensor stopped working

Post by j.morin27 » Fri Apr 23, 2021 8:49 pm

Was the watch on the charger the whole time? Some people theorized that the charger or charging was to blame for the sensor failure. Maybe it's some small short? I hope not because that would mean hardware fault.
Seeing as you can still get readings maybe it's just a software fault. As to a fix, check the https://forum.mobvoi.com/viewtopic.php?f=76&t=56647 thread. Sadly I don't think there has been a fix for it.

Post Reply