Modifying ESP32 Mini to Focus on AS7341

In order to eliminate Mozzi audio glitches while reading AS7341 spectral color sensor, I was prepared to dive down to learn ESP-IDF I2C API. Fortunately, it turned out Adafruit AS7341 library’s provision for asynchronous read (sensor integration occurs while Arduino code continues running) was good enough to eliminate those popping noises. This brought one project to a rapid conclusion so I can contemplate my next one.

I’ve barely scratched the surface of this AS7341’s capabilities, and I still haven’t quite grasped the meaning of all those numbers that it generated. I don’t have an intuitive grasp of how the set of numbers generated by this sensor relates to how human eyes perceive color. I want to further explore the AS7341 and take it around the house to measure different things, but the contraption I have on hand is quite cumbersome with its STEMMA QT compatible wiring for the AS7341 and a salvaged 3.5mm jack for connecting an audio cable.

To focus on AS7341, I will leave the audio subsystem behind for my next set of experiments. After I unsoldered the 3.5mm jack for audio output, I am much less likely to catch an inconvenient wire and risk damaging my test circuit. I then wrapped the ESP32 mini and wires to the AS7341 sensor inside a bit of clear heat-shrink tube (*) so I am no longer handling bare circuit board. The micro-USB connector would serve as the best metal contact point for grounding purposes, so it was left outside of the shrink-wrapped area as was the reset button that should remain accessible.

(If this is all I wanted to do, and I knew this to begin with, I would have used something like an Adafruit QT Py ESP32 Pico. But I’m sure I will want to do more down the line, and I’m making it up as I go along.)

In addition to a large white LED intended to provide illumination for the color sensor, Adafruit’s AS7341 board also has a bright green LED to indicate power. I’m worried this LED’s green light might distort color sensor results. I like the idea of a power LED indicator, but I would have much rather preferred a dim green glow over this bright beacon. [In contrast, DFRobot’s AS7341 board does not have a bright LED close to the sensor.]

I thought about unsoldering either the LED itself or its adjacent current-limiting resistor, but they are right next to a STEMMA QT connector and I think my hot-air gun would melt and damage its plastic. Then I had a better idea: I put on a small piece of double-sided foam tape. (“Servo tape” from the world of remote-control hobby.) It is an easily reversible modification that blocked majority of green light, good enough to let me contemplate the software side of my next project.

[UPDATE: As of April 26, 2023 Adafruit has updated this product with a cuttable jumper to disable power LED.]

(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.

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