Freediag is a suite of vehicle diagnostic protocols and an OBD II (mostly) compliant ScanTool, currently for Linux platforms. Multiple graphical user interfaces for scantool are under development - but right now, you have to use a command-line interface to scantool.
OBD II is a standard for vehicle diagnostics relating to emissions implemented on all US vehicles since the mid 1990s. Europe has just introduced a standard called EOBD which is basically the same.
The idea is that any garage/workshop will have a scantool and can diagnose vehicles with emissions problems - these are brought to the attention of the driver by a "Check Engine" light.
This suite also contains protocol suites for some manufacturer specific protocols such as the protocol used on some Mercedes Benz gearbox controllers. It is intended to add the VW diagnostic protocol shortly.
It is intended that this grow into a full blown diagnostic suite for configuring and checking faults on many vehicles.
There are 4 physical interfaces specified for vehicles, ISO9141 (K-Line), ISO14230 (effectively the same as ISO9141), SAE-J1850 VPW and SAE-J1850 PWM. A 5th interface type (CANbus) is specified but not used for standardised OBDII diagnostics.
The bulk of the original code and design was written by Richard Almeida, the code was then checked and made more portable as the first stage of a project to make it portable to Windows by Andy Whittaker. Much work has been done by Bjorn Helgaas on enhancing the usability of the scantool, sanitising the comments in the code and adding functionality to the scantool.
As of March 2004, there has been a complete break between the original developers and the present maintainers - so I cannot tell precisely who contributed what before August 2003. If you were a contributor and would like to be credited here - please let me know.
Steve Baker is the current 'owner' of the package.
Current Release: 0.3 The 0.3 release is the last one made by the original team. We are working towards a dramatically cleaned up version that will be numbered 1.0.0, but if you wish to experiment with that, you'll have to get it from CVS.
Vehicle Protocol Support: