Interest in "real" light sensor

[lorenzspenger]

Since I can't shake the idea of implementing a light sensor for the whole range 0~100,000 lx, I would like to know if someone else would be interested in this modification or if @rbaron would be interested to merge it into this project.

My idea is to use a digital ambient light sensor like the TI OPT3001 and connect it onto the I2C bus which is already used for the SHTC3.
This would mean a significant increase in costs / PCB, since this sensor alone costs ~1$ USD.

Another issue would be power consumption: I don't know how long the sensor read cycle takes at the moment. After skimming the datasheet the TI sensor it seems to need at least 100ms +-10ms for a measurement + 10ms for the range assessment measurement beforehand. During this time the current consumption is max. 3.7 µA, but typically 1.8 µA. I don't think this should pose an issue.
I'm more concerned about the shutdown/quiescient current of 0.3-0.4 µA. But this could be mitigated by a controllable power supply for the component if this should be too high.

If someone would like to join me on this endeavour I would be glad since this would be my real first foray into designing a hw component on a PCB.

[rbaron]

Hey @thatslolo,

Just a few thoughts. As you noticed, the phototransistor is a pretty basic light sensor. I personally use a case with my sensors (which I highly recommend for protection), so I have limited use for the light sensor. I think some people might find it useful (and/or use a transparent case, not sure how that would affect the measurements). Right now the phototransistor is so cheap that I still populate my boards. For a more expensive sensor, it would be nice to have the option to not populate it and indicate it in software IMO.

For the power-on state, I think 3.7 uA is negligible, so I wouldn't worry too much. For shutdown, 0.4 uA would be roughly 10% of the overall deep sleep current. It seems like you could power the sensor through a GPIO, but I'd check if there are significant differences between a cold start and a warm start from shutdown mode.

Unfortunately I won't have much free time to work on this, but I'm happy to merge it, at least in a different branch + link on wiki and/or link your fork once you test and power profile it.

[lorenzspenger]

Hey @rbaron,

thanks for the reply and sorry that it took me so long to come back to you. At the moment time is also sparse for me.

I will track the progress in this thread as soon as I progress.

[rbaron]

Closing due to inactivity.