Moving this conversation here:
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Hi Akiba,
Oh, your answer is great!
My idea is to build a DL that allows,

Light registration, with time stamp, when it exceeds a certain threshold (To control the human presence in the cave) The card only has to record when this threshold is exceeded to save energy

Periodic record of temperature and humidity

Data recording on SD

Autonomy of at least 4 months

I have tried some sensors and I think I will use the TSL2591 because it has a very low detection threshold (0.18 uLux) and has an interrupt pin. I've already been testing some sample libraries, and I think it would be ideal
For temperature and humidity I am hesitating between using the DHT11 or the BME280
Perfect the external reference of the ADC if it serves to have more accurate readings
My idea is to use a power bank with 3 or 4 18650 Lipo batteries and built-in BCP, and to be able to disconnect the device when it detects that the power supply is less than 3.2V
Is the Sandisk card you mention a normal one, or of an industrial type like the one you presented in the corresponding module?
My best wishes,

The TSL25911 chip looks really interesting. I didn't realize the lux metering chips have interrupts on them. I think your idea exposes two potential improvements for Wildlogger. The first, of course, is that the TSL25911 module should come into existence. There's a slight hiccup where it uses the I2C interface and an interrupt pin. We can work around this by having two connectors on it. One would be the 4-pin connector to the I2C interface on the Wildlogger board. The other is to have a 3-pin connector for the interrupt (PIR) interface. We would only use one pin on that though. It's a bit of a hack but doable. 

Regarding the BME280, we actually already have these modules that can be directly plugged into the WildLogger's I2C port. We actually use these quite often in other projects. 

The other thing is that it makes me realize we should also provide cables that can interface to add-on boards from other modular systems like the Adafruit Stemma and Seeed Grove. That way, it opens up the WildLogger to multiple ecosystems. 

We'll update this thread when these will be available, but likely after the course ends. In the meantime, you can also try to interface using the Adafruit breakout boards. 

Akiba