FlexCAN RM0046
532/936 Doc ID 16912 Rev 5
in the EMI environment of a vehicle, cost-effectiveness and required bandwidth. The
FlexCAN module is a full implementation of the CAN protocol specification, Version 2.0 B,
which supports both standard and extended message frames. 32 Message Buffers are
supported. The Message Buffers are stored in an embedded RAM dedicated to the
FlexCAN module.
The CAN Protocol Interface (CPI) submodule manages the serial communication on the
CAN bus, requesting RAM access for receiving and transmitting message frames, validating
received messages and performing error handling. The Message Buffer Management
(MBM) submodule handles Message Buffer selection for reception and transmission, taking
care of arbitration and ID matching algorithms. The Bus Interface Unit (BIU) submodule
controls the access to and from the internal interface bus, in order to establish connection to
the CPU and to other blocks. Clocks, address and data buses, interrupt outputs and test
signals are accessed through the Bus Interface Unit.
One FlexCAN module is implemented on the SPC560P40/34 device.
22.1.2 FlexCAN module features
The FlexCAN module includes these features:
● Full Implementation of the CAN protocol specification, Version 2.0B
– Standard data and remote frames
– Extended data and remote frames
– 0 to 8 bytes data length
– Programmable bit rate as high as 1 Mbit/s
– Content-related addressing
● 32 Flexible Message Buffers (MBs) of 0 to 8 bytes data length
● Each MB configurable as Rx or Tx, all supporting standard and extended messages
● Individual Rx Mask Registers per Message Buffer
● Includes 544 bytes (32 MBs) of RAM used for MB storage
● Includes 128 bytes (32 MBs) of RAM used for individual Rx Mask Registers
● Full-featured Rx FIFO with storage capacity for 6 frames and internal pointer handling
● Powerful Rx FIFO ID filtering, capable of matching incoming IDs against either 8
extended, 16 standard, or 32 partial (8-bit) IDs, with individual masking capability
● Selectable backwards compatibility with previous FlexCAN version
● Programmable clock source to the CAN Protocol Interface, either bus clock or crystal
oscillator
● Unused MB and Rx Mask Register space can be used as general purpose RAM space
● Listen-only mode capability
● Programmable loop-back mode supporting self-test operation
● Programmable transmission priority scheme: lowest ID, lowest buffer number or highest
priority
● Time Stamp based on 16-bit free-running timer
● Global network time, synchronized by a specific message
● Maskable interrupts
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