CAN is aserial bus for interconnecting a central controller network in limited area. The controller provide the control for brakes,engines,front display panel, meters display panel and cruising
CAN bus line usually interconnect to a CAN controller between line and host at the node. It gives the inputs and gets output between the physical and data link laywer at the host node.
The CAN controller has a BIU protocol controller, status control registers, receiver buffer and message objects. These units connect the host node through the host interface circuit.
The embedded controller are networked and are controlled through a controller network bus. A network of number of CAN controler and CAN devices on a CAN bus
THREE STANDARDS
1. 33 kbps CAN
2. 110 kbps fault tolerant CAN
3. 1 Mbps high speed CAN
CAN has a serial line , which is bidirectional. A CAN device receive or send a bit at an instance by operating at the maximum rate of 1 mbps . It employ a twisted pair connection to each node. The pair runs upto a maximum rate of 40m. A CAN version also functions up to 2Mbps. CAN bus is a standard bus in distributed network. CAN is mainly used in automotive electronics. It is also used in medical electronics and industrial plant.
FIRST FIELD OF 12 BITS
Arbitraction field contains packet 11-bit destination address (ID) and an RTR stands for ‘Remote Transmission request’. The devi e is at destination address specified by ID in 11-bit sub-filed. 11-bit address idenrifies the device to which data is being made. When RTR bit us destination address. If this bit is at ‘0’ it means this packet is arequest for the data from the device
SECOND FIELD OF 6 BITS
It is aclled the control field. The first bit is the identifier extension. The second bit is always ‘1’, The last 4 bits are code for data length.
THIRD FIELD OF 0 TO 64 BITS
Its length depend on the data length code in the control field.
FOURTH FIELD IS OF 16 BITS
It is the CRC bits. The receiver node uses it to decet error, if any, during the tranmisssion.
FIFTH FIELD OF 2 BITS
First bit is the ‘ACKslot ’ . The sender sends it as ‘1’ and receiver sends back ‘0’ in the reception.
SIXTH FIELD OF 7 BITS
It is for end of the frame specification and has seven ‘0’s.
INTERFRAME BITS
Minimum 3 bits separate two CAN frames.
