OBD Reader

Using a Parallax Propeller microcontroller to control an OBD interface via RS232, the results of diagnostic tests and live engine data can be displayed on an LCD display.  By writing data to a 2GB SD card, data is available for analysis, as per the chart below.  Don’t forget - this is in 32 kB of memory.

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Protoboard

A Parallax Propeller Protoboard was used to validate the initial design.

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Final Version

The box ended up like that to the left.  The ELM327 to serial box talks to the car and the lash-up in the project box works on the data from that.  A VGA output is used to present data to a monitor if required.

In addition to engine data, the box can display/record acceleration data.

Output

The data recorded provided all aorts of opportunities for charts and plots.