A collection of information about OBD2
Relevant SAE specs (documents removed due to SAE copyright)
- SAE J1850: describes the network hardware, the electrical specification, basic protocol, and CRC byte
- SAE J2178 part 1: describes the 2 types of packet headers and typical physical node address assignments
- SAE J2178 part 2: describes the standard data to be exchanged on the network, including scaling, ranges, and transfer functions
- SAE J2178 part 4: describes the message assignments for the three byte form of the consolidated header format.
- SAE J2190: describes the phyically addressed messages used for diagnostics, trouble codes, freeze frame data, and reflashing.
Some related datasheets
- 4Mbit/512KByte Intel flash chip used in some OBD2 PCMs
- ELM 322 single chip VPW <-> RS232 converter from Elm Electronics
- MC68332 processor used in more recent OBD2 PCMs
- MC68HC58 VPW interface chip used in some OBD2 PCMs.
- BDLC (Byte Data Link Controller), a VPW interface embedded in some Motorola microcontrollers
- M68HC12B a 68HC12 microcontroller that includes a BDLC
- HIP7010 byte level interface from Harris/Intersil, now sold to AMI Semiconductor, may be obsolete
- HIP7020 J1850 line transceiver from Harris/Intersil, now sold to AMI Semiconductor, may be obsolete
- AU5783 J1850 line transceiver from Phillips.
- L5951 J1850 line transceiver plus triple integrated regulator (3v3, 5v0, 7v8) from ST
- Whitepaper from Intel about the j1850 electrical specification.
- App note AN1212 from Motorola about J1850 communications
- App note AN1731 from Motorola, schematics and code for a simple OBD2 scan tool
- Engineering bulletin 601 from Motorola, initializing the BDLC
- Flash socket from Yamaichi, low profile ZIF
Other internet resources