
CHAPTER 19 CAN CONTROLLER
Preliminary User’s Manual U16541EJ1V0UM
658
(21) CAN0 message configuration register (C0MCONFm)
7
6543210
Address
Initial value
C0MCONFm
OWS
RTR
MT2
MT1
MT0
0
MA0
FFFECxx9H
xxxxxxxxB
OWS
Overwrite Select Bit
0
A newly received data frame does not overwrite the occupied message buffer
Note
. The newly received data
frame is discarded.
1
A newly received data frame overwrites an occupied message buffer
Note An occupied message buffer means a receive message buffer into which a data frame has already
been accepted (i.e. DN is set(1)), but the CPU has not yet read that message buffer.
RTR
Remote Frame Request Bit
Note
0
Data frame transmission
1
Remote frame transmission
Note The RTR bit only determines the message frame for the transmission process from a message buffer
defined as transmit message buffer (i.e. MT2 to MT0 = 00H).
Upon valid reception of a remote frame, RTR remains cleared (0) in the corresponding transmit
message buffer.
If a transmit message buffer is prepared to send a remote frame by setting the RTR bit (1) and a remote
frame is received in parallel from the CAN bus, that received remote frame is not accepted by the
message buffer. That is, no interrupt generation, no update of the DN flag, no update of the MDLC3 to
MDLC0 bit string and no update of the receive history list will be issued for that buffer.
MT2
MT1
MT0
Message Buffer Type
0
Message buffer is a transmit message buffer.
0
1
Message buffer is a receive message buffer not linked to a mask in the assigned CAN I/F
channel.
0
1
0
Message buffer is a receive message buffer linked to mask 1 in the assigned CAN I/F
channel.
0
1
Message buffer is a receive message buffer linked to mask 2 in the assigned CAN I/F
channel.
1
0
Message buffer is a receive message buffer linked to mask 3 in the assigned CAN I/F
channel.
1
0
1
Message buffer is a receive message buffer linked to mask 4 in the assigned CAN I/F
channel.
Other than above
Setting prohibited.
MA0
Message Buffer Assignment
0
A message buffer is not assigned to any CAN I/F channel.
1
A message buffer is assigned to CAN I/F channel 1.
Caution Be sure to set bits 2 and 1 to 0.