Simple CAN cape for the Beaglebone Black
This is a CAN transceiver evaluation board that can be used to develop a CAN bus or even to sniff a vehicle's CAN bus. By using an SOIC-8 breakout board, and adjusting the pin jumpers provided on the cape, any 3.3V or 5V SOIC-8 CAN transceiver can be tested. A demo of our project can be found on youtube: https://youtu.be/FzIJ83zwgUM
Accessing your vehicle's CAN bus can be a dangerous endeavor. Reading the bus is typically not a problem, however sending messages can disrupt the operation of the vehicle, cause trouble codes, and potentially lead to undesired operation of the vehicle, up to and including moving under its own discretion. Needless to say, this can FATALLY INJURE YOU, so be careful. We are not responsible for any outcomes that the use of the provided hardware design or software may cause. There is no warranty.
The installation of this project is relatively simple. First, begin by cloning the github repository:
beagle$ git clone https://github.com/SabeehKhan18/Beaglebone-CAN-Cape.git
Be sure you have disabled the HDMI in /boot/uEnv.txt by uncommenting:
dtb=am335x-boneblack-emmc-overlay.dtb
If you have not previously done the above, you will need to reboot after uncommenting the line.
Next, run the installation script included in the repo. The installation script installs the linux package can-utils on the beaglebone. This package has the software necessary to make sense of the messages on the bus and provides a display interface:
root@beagle$ cd Beaglebone-CAN-cape/
root@beagle$ ./install.sh
Then, be sure you are operating as root, and then source the setup script. This will configure the pin muxes for dcan1, which operates on P9_24 and P9_26. It also uses P8_13 to control the CAN transceiver STANDBY pin. Then it sets up the interface can1. You must provide the bitrate of the CAN bus as an argument, replacing BITRATE in the command below. If you are developing your own network, you should know this value as you should have selected it. If you are attempting to sniff a production vehicle, your best bet is to start with 500000, which is representative of 500 kbps. If this doesn`t work, try a google search to see if you can find the bitrate:
beagle$ source setup.sh BITRATE
After the above steps complete successfully, the can1 interface should be up and running. You can confirm this by running:
root@beagle$ ifconfig
You should see an interface can1 and, if you have connected to a bus and have entered the correct bitrate, you should see an RX count above 0.
If you have a can1 interface up and running, you now have a couple of can-utils you can use to view the messages. The first is:
root@beagle$ candump can1
This will dump all of the received CAN messages to the terminal.
If you want a more organized view, then cansniffer is your best bet. Run:
root@beagle$ cansniffer can1 -c
The cansniffer utility will display the messages received in the terminal as well, but it isn`t a scrolling list. When a message is received, and a previous message with that ID has already been received, the new data overwrites the old data. Further, the -c flag causes any differences in the data received from one message to the next to be highlighted in red.
To use the board and schematic files included in this repository, you will need to install EAGLE by Cadsoft. The freeware version is enough to open and edit this board. Simply copy the CAN-Cape directory to your EAGLE project directory, or change your EAGLE project directory to this repo on your machine. You will also need to include a library in your project, which is found in the Eagle-Libraries directory. You can find an EAGLE download here:
The board can be printed by sending gerber files to a PCB fab company. I used the Sparkfun DRU and CAM processor in order to check the board and generate the gerber files. They can be found here:
https://www.sparkfun.com/tutorials/115
A list of components can be found in PartsList.ods. Feel free to modify the hardware design to accomodate any components you would like to use.