Users Manual

R01UH0823EJ0110 Rev.1.10 Page 1276 of 1852
Nov 30, 2020
RX23W Group 36. CAN Module (RSCAN)
36.4 Reception Function
There are two reception types.
• Reception by receive buffers:
Zero to 16 receive buffers can be shared by all channels. Since messages stored in receive buffers are overwritten at
each reception, the latest receive data can always be read.
• Reception by receive FIFO buffers and transmit/receive FIFO buffers (receive mode):
Two receive FIFO buffers can be shared by all channels and one dedicated transmit/receive FIFO buffer is provided
for each channel. The FIFO buffers can hold the number of received messages set by the RFCCm.RFDC[2:0] bits
and CFCCL0.CFDC[2:0] bits, and messages can be read sequentially from the oldest.
36.4.1 Data Processing Using the Receive Rule Table
Data processing using the receive rule table allows selected messages to be stored in the specified buffer. Data processing
includes acceptance filter processing, DLC filter processing, routing processing, label addition processing, and mirror
function processing.
Up to 16 receive rules can be registered per channel. If receive rules are not set, no message can be received.
Figure 36.4
illustrates how receive rules are registered.
Figure 36.4 Entry of Receive Rules
Each receive rule consists of 12 bytes in the GAFLIDLj, GAFLIDHj, GAFLMLj, GAFLMHj, GAFLPLj, and GAFLPHj
registers. The GAFLIDLj and GAFLIDHj registers are used to set ID, IDE bit, RTR bit, and the mirror function, the
GAFLMLj and GAFLMHj registers are used to set mask, the GAFLPLj and GAFLPHj registers are used to set label
information to be added, DLC value, and storage receive buffer, and storage FIFO buffer.
(1) Acceptance Filter Processing
In the acceptance filter processing, the ID data, IDE bit, and RTR bit in a received message are compared with the ID
data, IDE bit, and RTR bit set in the receive rule of the corresponding channel. When all these bits match, the message
passes through the acceptance filter processing. The ID data, IDE bit, and RTR bit in a received message which
correspond to bits that are set to 0 (bits are not compared) in the GAFLMLj and GAFLMHj registers are not compared
and are regarded as matched.
Check begins with the receive rule with the smallest rule number of the corresponding channel. When all the bits to be
compared in a received message match the bits set in the receive rule or when all the receive rules are compared without
any match, filter processing stops. If there is no matching receive rule, the received message is not stored in the receive
buffer or FIFO buffer.
Receive rule 0
Receive rule 1
Receive rule j
Receive rule 15
RNC0[4:0]: Bits in the GAFLCFG register
Boundary is determined by
the RNC0[4:0] bits
Channel 0 receive rules 0 to j
j: The value of RNC0[4:0] - 1