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Section 20 Controller Area Network
Page 1082 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
20.9 Usage Notes
20.9.1 Notes on Port Setting for Multiple Channels Used as Single Channel
This module in this LSI has two channels and some of these channels can be used as a single
channel. When using multiple channels as a single channel, keep the following in mind.
CTx0
CRx0
CTx1
CRx1
PJ2
PJ3
Channel 0
(32 Mailboxes)
Channel 1
(32 Mailboxes)
Figure 20.30 Connection Example when Using This Module as 1-Channel Module
(64 Mailboxes 1 Channel)
1. No ACK error is detected even when any other nodes are not connected to the CAN bus. This
occurs when channel 1 transmits an ACK in the ACK field in response to a message channel 0
has transmitted.
Channel 1 receives a message which channel 0 has transmitted on the CAN bus and then
transmits an ACK in the ACK field. After that, channel 0 receives the ACK.
To avoid this, make channel 1 which is not currently used for transmission the listen-only
mode (TST[2:0] = B'001) or the reset state (MCR0 = 1). With this setting, only a channel
which transmits a message transmits an ACK.
2. Internal arbitration for channels 0 and 1 is independently controlled to determine the order of
transmission.
Although the internal arbitration is performed on 31 Mailboxes at a time, it is not performed on
64 Mailboxes at a time even though multiple channels function as a single channel.
3. Do not set the same transmission message ID in both channels 0 and 1.
Two messages may be transmitted from the two channels after arbitration on the CAN bus.