MCF5253 Reference Manual, Rev. 1Freescale Semiconductor 25-1Chapter 25FlexCAN ModuleThis chapter discusses the modes of operation, signals, memory map, register descriptions, and thefunctional and initialization sequence of the FlexCAN controller of the MCF5253.25.1 FeaturesFollowing are the main features of the FlexCAN module:• Full implementation of the CAN protocol specification version 2.0B— Standard data and remote frames (up to 109 bits long)— Extended data and remote frames (up to 127 bits long)— 0–8 bytes data length— Programmable bit rate up to 1 Mbps— Content-related addressing• Up to 32 flexible message buffers of zero to eight bytes data length, each configurable as Rx or Tx,all supporting standard and extended messages• Listen-only mode capability• Three programmable mask registers: global (for MBs 0–13 and 16–31), special for MB14, andspecial for MB15• Programmable transmission priority scheme: lowest ID or lowest buffer number• Time stamp based on 16-bit, free-running timer• Global network time, synchronized by a specific message• Programmable I/O modes• Maskable interrupts• Independent of the transmission medium (an external transceiver is assumed)• Open network architecture• Multimaster bus• High immunity to EMI• Short latency time due to an arbitration scheme for high-priority messages25.2 Block DiagramA block diagram describing the various submodules of the FlexCAN module is shown in Figure 25-1.Each submodule is described in detail in subsequent sections. The message buffer architecture is shown inFigure 25-2.
