My draft is all gone. I hate wix. Now I have to write it again.
BoM list:
BQ24074 USB Charging Board Module
SSD1351 OLED Module
LiPo Battery 500mAh
MAX4466 Microphone Module
Perf Board + Arduino Nano
Minor Bugs: I accidentally shorted two signal pins for the OLED module, but fixed it with re-soldering.
Everything is connected and working well. I cut the perf board to smaller sizes to fit my needs.
Except for one problem: The readings get really HIGH whenever solely powered by a battery through the charging board. When Arduino is powered by USB or by USB-C through the charging board, everything is fine. This is really weird and I suspect it has something to do with voltage or grounding. Debug is really hard because I cannot use Serial: I have to connect to Arduino via USB, which eliminates the bug. I tried to use a multimeter to measure the voltage input. From USB it's 3.3V, from the charging board it's always 4.6V (confirms Adafruit's spec sheet).
I'm powering my microphone module from the 3.3V port of Nano, which should also be regulated and shouldn't be affected by incoming voltage. I will debug this problem later, but for now, the machine lives with a power bank and it works pretty well.
The enclosure is designed to feature a removable Arduino Nano 33 so I could recycle the board later when I need it for something else. Very compact for a portable device. The design went through a few iterations to be both compact and makes best use of space.
Everything fits eventually, just not very tidy. You can see modules laying on top of each other.
Tada! It works and I'm bringing it to Philadelphia.
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