GMLAN Sniffer¶

Introduction¶

This project makes use of CAN on an LPC1768 to communicate with General Motors GMLAN network via a compatible transceiver. GMLAN is a single wire CAN Bus that operates at 33.333 kbit with 29-bit header packets and is commonly used for transmission of non-critical information between such nodes on automobiles as the following;

• Dash cluster
• Entertainment system (head unit)
• Satellite Navigation (OnStar for example)
• HVAC controls
• Immobiliser / alarm / other security systems
• Door locks and door status
• Power Windows
• Interior / exterior lighting
• Reversing sensors

The list is extensive, for a better idea of what can be done, view the ARBIDs tab on the GMLAN Bible Google Docs spreadsheet (tabs are at the bottom of the page).

Hardware setup¶

This is just one example of how you can interface with GMLAN using an SKPang CAN-Bus Breakout Board (based around an MCP2551 CAN Transceiver), using these instructions I assembled the following on my trusty prototyping board;

(Click to open high resolution version)