2018 Microchip Technology Inc. DS70005340A-page 3
CAN FD Protocol Module
Message Reception
• 32 Flexible Filter and Mask Objects
• Each Object can be Configured to Filter either:
- Standard ID and first 18 data bits or
- Extended ID
• 32-Bit Timestamp
• The CAN FD Bit Stream Processor (BSP) implements the Medium Access Control of the
CAN FD protocol described in ISO11898-1:2015. It serializes and deserializes the bit
stream, encodes and decodes the CAN FD frames, manages the medium access,
Acknowledges frames, and detects and signals errors.
• The TX handler prioritizes the messages that are requested for transmission by the
transmit FIFOs. It uses the RAM interface to fetch the transmit data from RAM and provides
it to the BSP for transmission.
• The BSP provides received messages to the RX handler. The RX handler uses an
acceptance filter to filter the messages that shall be stored in the receive FIFOs. It uses the
RAM interface to store received data into RAM.
• Each FIFO can be configured either as a transmit or receive FIFO. The FIFO control keeps
track of the FIFO head and tail, and calculates the user address. In a TX FIFO, the user
address points to the address in RAM where the data for the next transmit message is
stored. In an RX FIFO, the user address points to the address in RAM where the data of the
next receive message will be read. The user notifies the FIFO that a message is written to
or read from RAM by incrementing the head/tail of the FIFO.
• The TXQ is a special transmit FIFO that transmits the messages based on the ID of the
messages stored in the queue.
• The TEF stores the message IDs of the transmitted messages.
• A free-running Time Base Counter (TBC) is used to timestamp received messages.
Messages in the TEF can also be timestamped.
• The CAN FD controller module generates interrupts when new messages are received or
when messages are transmitted successfully.
To Next Page
Loading...
Need help?
General
