Hi All,
This is something I've been wanting to do for years, and I think I finally found a sensor that will work. I've always had trouble reading the API tests, and I've always been miffed that the reefers get the cool digital test readers - and wanted to take a crack at building one that could potentially read any freshwater test given a blank/known concentration as a calibration.
A sensor came out from ams (AS7343) in 2022 that unfortunately has been made EOL, but has a replacement (TCS34488M) with a similar package that might work for future versions.

I recently got my hands on a qwic version of the AS7343 sensor from sparkfun, and figured its time to put together something.
Goals:
- As cheap as possible
- Universal as possible
- Fit API glass/plastic vials (not sure yet if the plastic vials will read ok)
- Start with Nitrate/Phosphate and see if I can add more there
I figure I'll need 2 light sources (warm white, and IR for reading the phosphate test), but can use the same sensor array across most tests. I can use a small-form ESP32 as the MCU to give it USB-C power, wifi/bt connectivity if needed, and keep it small. Small/cheap ~1.3" OLED screen for displaying results/selecting tests.
Enclosure will be 3d printed.



First pass at a sketch - I might drop the screen if I can give the device a web interface though, which will make the device even smaller/cheaper, reduces the need for physical buttons on the unit, and a 2nd pcb entirely. Also not sure if it will need a cover for the top of the vial, or how much ambient light will affect the reads. TBD. Will order some XIAO ESP32S3 to play with and see how far I can take it.
I'll log progress here, and am very open to suggestions and ideas. If successful, I'll release the files so it can be easily replicated.