February 12, 2004
The purpose of this page is to document the design and creation of an Onboard Diagnostics II (OBD-II) interface and logger for an automobile that can be accessed via a PC. The circuit is based around the Elm electronics ELM323 microchip and will work in two separate modes. In the first mode, a PC is connected to the circuit while the automobile is running. This allows realtime OBD information to be retrieved and read. Also, trouble codes can be read and cleared. In the second mode, the ciruit is standalone and acts as a data logger. When the automobile is running, it will poll the OBD bus periodically for information and write this data to an eeprom. The circuit can later be attached to a PC and the logged data can be uploaded to the PC for analysis. For more detailed design/operation information, see the design info page.
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