You are right it would have to be pretty stable to put in ROM, but that doesn't mean you can't patch functions or link new versions. The ability to have some bt or wifi functionality in a wake stub would be great for battery applications. Obviously you aren't going to run a2dp in a wake stub but som...

If xRingbufferReceive returns null NumElements is not valid so you can't use it as a test ... unless you set it to 0

How many blocks are you seeing fail the first write attempt?

You need to clear the interrupt when you service it.

Generate one and store in nvs or efuse. Or use flash chip id https://www.esp32.com/viewtopic.php?t=1481

Afaik espeasy is a esp8266 firmware that won't run on esp32. Second, you have to flash a bootloader, partition table, and app to esp32.

https://esp-idf.readthedocs.io/en/lates ... notes.html

Without it connected to anything you are going to pick up noise values, more noise with the jumper wire acting as an antenna

Does this help: http://esp-idf.readthedocs.io/en/v2.1/