I am starting my very first Arduino project. It’s supposed to be an autonomous high precision luxmeter, used to work on very low light levels coming from the sky at night. Moreover, I want it to be able to measure the energy coming from the whole « half-sphere » of the sky. So I need multiple sensors (a « pyramid » of 4, I imagine) being read simultaneously (or one by one in a short amount of time, if not possible). No calibration to an industrial luxmeter is needed, it’s just for comparison.
The device has to :
- Take measurements for 1 week straight whithout changing the battery (maybe with a pause during daytime, to save power)
- Take a measurement spaced by 10min
- Take temperature level at the same time
- Log every data on an SD/microSD card
- Be as cheap as possible to make around twenty of them
- Be compact (I mean, i don’t want to power it with a big car battery, for instance)
Beyond my absence of skills in arduino programming, I’m facing some issues and need first advices :
- Autonomy of Arduino boards : these boards are quite power consuming, so I am looking for something less greedy. I think about some very-low-power-controllers like the Butterfly or Ladybug from TleraCorp (https://www.tindie.com/products/tleracorp/ladybug-stm32l432-development-board/). I have them now, but I have problems with RTC calibration and libraries…
- Choice of light sensor : In the multiple projects on low levels light meters found on the internet, it appears that the analog TSL237 gets the best results at low light levels, but, maybe with 4 of them, it’s to power greedy… So I’m thinking about I2C ones with low detectable minimum illuminance and high resolution (like VEML7700 or the new VEML6035). But with 4 of them I get an issue because they will all have the same i2c address…
- Choice of battery : I was originally thinking about a 10’000mAh lipo associated to a Butterfly board, but as I will maybe go to a more « classical » Arduino board, maybe will I need something more beefy ( ?)…
- For the t°, I’m thinking about BMP280 or BME280, but maybe it’s better to take a good old analog sensor ?
- Power consumption optimization : It will depend on the board, but is there some tips to keep the lowest power consumption from a board, to run it each 10 min, during one week ?
So if anyone could give me some tips, ideas, advices or links to get my project to its term, it would be really appreciated !
(hoping my problem is not too general to fit this “sensor” forum. maybe it would be better in “project guidance”, or “other hardware development”…)