I have a number of ESP32-based projects which are battery+solar-powered. If anything goes wrong with them, it can be a real pain to figure out what's wrong.

While developing, I always add helpful Serial.print commands in the code. They're not much help when in the field, because the only way I have to read them is a PC. Sometimes you can move the whole thing and get the output, but I thought there must be a better way. Especially as Sod's law says that the issue only happens in situ.

What I wanted was a hand-held serial terminal I could plug in and see the serial output. I searched for existing products and found Tiny Terminal 2, this had the functionality I wanted, but I couldn't have the time and inclination to source parts, assemble it and figure out how to flash it.

Then I came across the Serial USB Terminal Android app. This was perfect! All I needed was a phone which I always have on me and a USB-C to USB-micro (OTG) cable.