The next project is a set of car gauges.  I’ve taken apart an ELM327 mini obd2 adapter, and removed the bluetooth board.  For testing I have this hooked up to a cp2102 usb to serial breakout and am talking to it with a serial terminal. Power is soldered on to the board and provided by a 12V wall wart. The next step is to hook it up to an esp8266 (esp-12) that can drive a bunch of oled displays. (see the previous post).  I won’t be using the wifi on the esp board, but the module is just so handy that it seems a logical choice.  I get 3.3v off of the ELM327 dongle, so it it just four wires from the dongle to the gauges.

The dongle talks at 38400, eg:

>01
SEARCHING... UNABLE TO CONNECT
>ATZ
ELM327 v1.5 
>atrv 
11.9