ELM327 v2.2 : OBD to RS232 Interpreter – firmware version 2.2

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Almost all of the automobiles produced today are required, by law, to provide an interface for the connection of diagnostic test equipment. The data transfer on these interfaces follow several standards, but none of them are directly usable by PCs or smart devices. The ELM327 is designed to act as a bridge between these On-Board Diagnostics (OBD) ports and a standard serial interface.

In addition to being able to automatically detect and interpret nine OBD protocols, the ELM327 also provides support for high speed communications, a low power sleep mode, and the J1939 truck and bus standard. It is also completely customizable, should you wish to alter it to more closely suit your needs.

The data sheet discusses all of the ELM327’s features in detail, how to use it and configure it, as well as providing some background information on the protocols that are supported. There are also schematic diagrams and tips to help you to interface to microprocessors, construct a basic scan tool, and to use the low power mode.


  • Power Control with standby mode
  • Universal serial (RS232) interface
  • Automatically searches for protocols
  • Fully configurable with AT commands
  • Low power CMOS design


Figure 1 : ELM 327 Block Diagram


  • Diagnostic trouble code readers
  • Automotive scan tools
  • Teaching aids

ELM 327 Pin Out

Farees Ahmed

The aim of this blog is to serve as a quick reference guide for the Curious. Appreciate your feedback and comments !