Controller–Area Network
Hard Drive Recovery - Controller–Area Network
Controller–area network (CAN) is a vehicle bus standard designed to let microcontrollers and devices to communicate with each other within a vehicle without the presence of a host computer. Though it was designed specifically for automotive applications, it is now also used in other areas.
Development of the CAN-bus started in 1983 at Robert Bosch GmbH. The protocol was released in 1986 at the Society of Automotive Engineers congress in Detroit. The first CAN controller chips, produced by Intel and Philips, came to the market in 1987. Bosch published the CAN 2.0 specification in 1991.
The CAN bus is used in vehicles to connect engine control unit and transmission, or to connect the door locks, climate control, seat control, etc. on a different bus. It is also used as a field bus in general automation environments, due to the low cost of CAN controllers and processors.
Bosch holds patents on the technology. Manufacturers of products with custom ASICs or FPGAs containing CAN-compatible modules, need to pay fee for the CAN Protocol License. Manufacturers of CAN-compatible microprocessors pay license fees to Bosch, which is passed on to customers in the price of the chip.
The devices that are connected by a CAN network are sensors, actuators and control devices. A CAN message never reaches these devices directly. Instead a host-processor and a CAN controller are required between these devices and the bus. If the bus is free, any node may begin to transmit. If two or more nodes begin sending messages at the same time, the message with the more dominant ID will overwrite other nodes’ less dominant IDs, and only the dominant message remains and is received by all nodes.
