M16C Datasheet, PDF (174/262 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Preliminary Specifications REV.B
Mitsubishi microcomputers
Specifications in this manual are tentative and subject to change.
M16C / 6N Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
CAN Module
Reception- and Transmission Modes
TrmReq
0
0
1
1
RecReq
0
1
0
0
Remote
-
0
1
0
RspLock
-
-
0
0
Description
Configuration Mode
CPU could configure new transfer mode for this mailbox.
Mailbox is configured as a Receivebox for Dataframes.
1. Step: Mailbox transmits Remoteframe (RemAct-Bit is 1)
2. Step: Mailbox becomes a Receivebox for Dataframes
- RemActive-Bit is set to 0.
Exception: When the matching dataframe is already detected on the busline
before the remoteframe can be sent, the mailbox becomes immediately a
Receivebox for Dataframes.
Mailbox is configured as a Transmissionbox for Dataframes.
1. Step: Mailbox receives a Remoteframe (RemAct-Bit is 1).
2. Step: Mailbox becomes a Transmissionbox for Dataframes
0
1
1
1/0
- RemActive-Bit will be set to 0.
Remark: As long as RspLock=1, no transmission can be started. This means
that Remoteframes are not answered automatically.
Table 18-3. Table of all reception- and transmission modes
Notes - Reception Mode
• A received message, which fulfills the comparison conditions of several mailboxes, will be stored in the first
suitable mailbox starting with the Message Mailbox Slot0 (special case for the 'Basic CAN' feature). This
means the message will be stored only one time.
• When the CAN module transmits a message, the CAN module receives its own message. However,
the CAN module does not store that message in the normal operation mode, even if there is a receive box
with a fitting identifier. In case the CAN module operates in the 'loop back' mode (CAN Control Register),
the transmitted message is stored in a prepared mailbox (receivebox with corresponding identifier).
Notes - Transmission Mode
• Overwrite Procedure of an activated Transmission Mailbox
- In order to activate a transmission mailbox, set the configuration bits according to table 18-3.
- In order to overwrite the content of a transmission mailbox, deactivate the transmission mailbox. This
means, the CPU must clear the TrmReq-Bit (together with the RecReq-Bit!).
- The CPU has to read the TrmActive-Bit to check its current status. When the TrmActive-Bit is '0', the
abort request is successful and the CPU can overwrite the data of the transmission mailbox.
- After this check, the CPU has the possibility to determine whether the message is transmitted or not. The
abort request by CPU side is executed (successful), in case the SentData-Bit is not set. Otherwise the
message is transmitted successfully in spite of the abort request.
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