Does it ever happened to you that one of your Raspberry Pis falls into boot loop somewhere on the top shelf? Every Pi running from sdcard is doomed to refuse to work one day (unless you run them from read-only filesystem, which you should do BTW).
When that happens I usually disconnect it and bring to the bench to check serial console. Recently It took me more time to actually disassemble device from it's place, than actually fixing it. That get me thinking, surely some people made ESP8266 serial bridge over-the-air, and surely I'd like to have one nearby, next time ping is not coming back.
Not long after first prototype was born, fast forward few month I have revision A board on my bench. Short feature list
- ESP82266 with WifiManager
- One Serial connected to the host, another accessible via header for debugging purposes
- RGB led for status indication (If connected to Wifi and if connected to client)
- On-Board Li-Ion battery and battary management circuit
Here how it works in a nutshell
And below is a pinout for my specific implementation
Make sure that all parts came in good shape and no apparent damage is done on the way. Flash Terminal software to Wemos D1 board just to make sure it works.
Solder Wemos D1 module - headers to module first
Solder headers to the Wemos D1 module. Long part of the header should be directed to the motherboard. Make sure to align them right, use motherboard as an aligning tool. When soldered it will be tightly pressed against battery socket.
Start with just one pin each side and double check your work. Then you can proceed to other pins.
Solder Wemos D1 module - motherboard side
Solder headers to the motherboard from the back side.
Is it possible to use that device to control by RS-232 some devices ? Does it output some standard RS-232 levels ? I would use it with ESPHome and Home Assistant to control some devices through UART ;)