Information

• Short latency time due to an arbitration scheme for high-priority messages
• Low power modes, with programmable wake up on bus activity
New major features are also provided:
• Remote request frames may be handled automatically or by software
• CAN bit time settings and configuration bits can only be written in Freeze mode
• Tx mailbox status (Lowest priority buffer or empty buffer)
• IDHIT register for received frames
• SYNC bit status to inform that the module is synchronous with CAN bus
•
• CRC status for transmitted message
• Rx FIFO Global Mask register
• Selectable priority between Mailboxes and Rx FIFO during matching process
• Powerful Rx FIFO ID filtering, capable of matching incoming IDs against either 128
extended, 256 standard, or 512 partial (8 bits) IDs, with up to 32 individual masking
capability
• 100% backward compatibility with previous FlexCAN version
45.1.3 Modes of operation
The FlexCAN module has these functional modes:
• Normal mode (User or Supervisor):
In Normal mode, the module operates receiving and/or transmitting message frames,
errors are handled normally and all the CAN Protocol functions are enabled. User
and Supervisor Modes differ in the access to some restricted control registers.
• Freeze mode:
It is enabled when the FRZ bit in MCR is asserted. If enabled, Freeze mode is
entered when the HALT bit in MCR is set or when Debug mode is requested at MCU
level and the FRZ_ACK bit in MCR is asserted by the FlexCAN. In this mode, no
transmission or reception of frames is done and synchronicity to the CAN bus is lost.
See Freeze mode for more information.
Introduction
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
1106
Preliminary
Freescale Semiconductor, Inc.
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