FPGA Implementation of Manchester Line Encoding for Frame Length Compression Scheme in CAN(Controller Area Network) Controller

CAN(Controller Area Network) is now getting popular because of its expanding applications especially in automotive industry. CAN protocol uses NRZ(Non Return to Zero) line encoding. Long NRZ messages may cause problems in receivers such as clock drift means that if there are no edges, receivers lose tracks of bits. As a solutions, stuff bits are extra bits added to force transitions regardless of data. However, stuff bits cause jitters during transmission and due to this extra frame for stuff bits, it reduces the frame rate of the controller. In this paper, a frame length compression scheme to improve the features of CAN controller is presented. Modified Manchester Line Encoding is implemented in this CAN controller. The proposed scheme is synthesized on the Xilinx Virtex-5 FPGA by using Verilog HDL. The simulation results shows that the Modified Manchester Line Encoding is better than the original Line NRZ encoding technique in terms of clock synchronization and frame length compression in CAN communications.