The confuser was slightly rewired & wrapped up more thoroughly.  Lions couldn't think of how a 3D printed enclosure would be any better than packing tape.  It has to be as compact as possible.  It's still going to go inside a good old arm band with a battery.

Lions measure the CPU temperature with /sys/devices/virtual/thermal/thermal_zone0/temp

It shows 51C when it's warmed up, even though it smells like magic smoke.

Molex connectors have been disappointing as audio connectors.  Not sure why the ages old TRS connector does such a better job.  It takes a lot of fiddling to get a good microphone connection out of a molex.  This application doesn't have enough room for an XLR.

Discovered the UART RX has to be floating for it to boot up, otherwise it gets stuck in the bootloader.  This is the opposite of the STM32 which needs UART RX to be grounded.

The lion kingdom has had growing disappointment with raspberry pi's as audio recorders.  There's a lot to think about, to get them to boot, defeat wifi interference.  There's a long startup time while waiting to see if they work or need another reboot.  They always have buffer overruns.  They take up a lot of space & burn 300mA, even in the zero W size.  The wifi has never been as reliable as hoped.  Transferring files is super slow.

There have been thoughts of going to a more expensive STM32, SD card, surplus LCD, audio codec chip, analog trimpots, USB file transfer, single record button, but lions just don't make enough recordings to go beyond the minimal raspberry pi.