{"id":93,"date":"2012-02-24T21:33:27","date_gmt":"2012-02-25T02:33:27","guid":{"rendered":"http:\/\/www.mcgurrin.com\/robots\/?p=93"},"modified":"2012-02-24T21:33:27","modified_gmt":"2012-02-25T02:33:27","slug":"an-open-hwsw-api-for-your-car","status":"publish","type":"post","link":"https:\/\/www.mcgurrin.info\/robots\/93\/","title":{"rendered":"An Open HW\/SW API for Your Car"},"content":{"rendered":"

Today’s post is a bit of a diversion, but I think it will be of interest to almost everyone interested in hobby robotics.\u00a0 Rather than about robotic vehicles, it’s about a new system in development that will let us develop our own apps based on data from the full-sized car you drive around in.\u00a0 About 5 years ago in my day job, I argued the future of in-vehicle electronics would include an automaker supported read-only interface to the data bus, available to third party developers to build upon.\u00a0 Many auto company engineers I worked with stated this would never happen and never be supported.\u00a0 Well, for some car companies, #define\u00a0 NEVER\u00a0 5<\/p>\n

Introduction<\/strong><\/p>\n

“Many companies are already offering tools to hook into the driver’s interface, but for the most part they have limited availability for hobbyists and developers. What if the system was designed from the ground up to be open source and to give insight into the vehicle itself?”\u00a0 This sounds like a Maker’s daydream, but it’s about to be reality, at least for Ford owners.\u00a0 Ford Motor Company<\/a> and Bug Labs<\/a> have teamed up to produce the OpenXC Platform<\/a>, now in limited beta testing.<\/p>\n

This will provide read-only access via USB to many vehicle parameters in real-time, allowing developers, including hobbyists, to write applications running on whatever hardware they choose to interface.\u00a0 The system is currently in limited beta testing.\u00a0 According to press reports, beta testers include the University of Michigan, MIT, Stanford, Weather Underground, and India\u2019s HCL Technologies.<\/a><\/p>\n

Background<\/strong><\/p>\n

All modern cars use a data bus, the CAN bus<\/a>, for exchanging information between the various electronic controller modules and other devices found on today’s cars.\u00a0 One device on the bus provides a port for accessing the bus.\u00a0 It is often found somewhere near the driver under the dashboard.\u00a0 This On Board Diagnostics II (OBD-II<\/a>) port is required by law, as it is used to check for proper operation of air pollution control equipment.\u00a0 \u00a0 However, once it was required, automakers began using it as a general diagnostics port.\u00a0 There are standard codes<\/a> for much of the data, however automakers are not required to support most of these codes, and also typically add proprietary codes. The codes and their availability also vary by model and model year.<\/p>\n

the OpenXC Platform<\/strong><\/p>\n

<\/strong>\"\"Based on my reading of the project’s website<\/a>,\u00a0 the project provides a read-only interface (called the CAN translator module) that takes data from the OBD-II port, translates it into non-proprietary codes, and makes it available over a USB port.\u00a0 Apparently the hardware in the reference implementation uses a ChipKit board<\/a>, which uses a PIC microcontroller but can run Arduino code, along with a network shield. \u00a0 They state that the initial testers have access to the C code, but I’m wondering if it will be released to hobbyists, as it may give insights into Ford’s proprietary codes (they imply as much, stating that automakers might just supply compiled code).\u00a0 You can plug whatever you want into the USB port, but they are developing a reference implementation built around an Android tablet computer.<\/p>\n

While there are over 100 data elements available from the OBD-II, they are starting with support for just a subset, which can be found on the project’s Signal Translation Specification <\/a>page.\u00a0 They include:<\/p>\n