Tinkering with ODB II and the CAN bus

April 17, 2012 By Leave a Comment

[Debrah] is taking his next project out to the garage. He built his own CAN bus reader using a dsPIC.

The nice thing about working with Control Area Network is that it’s a universal standard found on every modern production line automobile. And because of this, the chip you need in order to communicate using that protocol will cost just over a dollar. [Debraj] chose the MCP2551, which comes in several different 8-pin packages. There is even an application note tailored for use with the dsPIC33F family.

The project is running on both 5V and 3.3V rails. This complicates things just a bit, but a level converter makes sure that there’s no communications problems between the chips. A four line character LCD acts as the output during the tests (you can see this in the clip after the break) but he’s already got a second version which looks quite a bit better on the dashboard.

What else can be done with this hack? Well, we’ve seen a method used to read control buttons from the steering wheel before. It all depends on what data your vehicle is transmitting and one way to find that out is to build some hardware and start logging the packets. [Read more…]

Filed Under: transportation hacks Tagged With: , , , ,

CAN bus for home automation

March 7, 2012 By Leave a Comment

Here’s one node on the new home automation system on which [Black Rynius] is working. So far he’s testing out the system with just two nodes, but plans to build more as the project progresses. He’s chosen to use the CAN bus for communications; a protocol which is most commonly found in automotive applications.

The biggest plus about using the CAN bus is that it requires just one pair of wires for communications. As you can see, there’s an old doorbell included on this board and he’s hoping to use the existing doorbell wire to connect between nodes. Each unit includes a PIC 18F4580 which has a CAN engine built into it for easy protocol translation. There is also an MCP2551 which handles the transmissions. You can read a bit more about the hardware choices in his breadboarding post.

So far almost everything is working as planned. He’s able to send and receive data between the two boards including temperature from a sensor and time from a DS1305 RTC chip. The one thing that vexes him is that doorbell. It draws too much current for the wall wart that’s powering the board, browning out the microcontroller and causing a reset. That’s not a hard fix and we look forward to more developments in the near future.

[via Dangerous Prototypes]

Filed Under: home hacks Tagged With: , , ,