ESP8266 Community Forum

- Sun Nov 26, 2017 2:20 am #72078 hey Experts
i am working on project for sending various pids of vehicle to my server using mqtt . i was thinking a way for my usb based elm327 obd2 to communicate with my esp8266.would simply connecting D+ and D- to rx and tx will
work or i would be requiring some extra converter ?

Thank you

Regards
saif

- Sun Nov 26, 2017 9:55 am #72083 OBD2 uses 12V or 5V signaling, depending on implementation, so at minimum you'd need a voltage shifter. Some versions signal using PWM, while others use ttl serial. So it depends on the make/model/market/year

- Fri Dec 01, 2017 6:45 pm #72228 You could take a normal ELM327 and connect its RS232 (at TTL-level) to an ESP using a 5V-3.3V levelshifter without problems.
The 12V of the car's power and CAN/J1850 and ISO-bus-voltages will be regulated to the proper levels before it even reaches the ELM.


In the ESP firmware just talk to the ESP at 38400 Baud (or 9600 Baud when the ELM is in sleep mode).

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.