CHAPTER 19 FCAN CONTROLLER (V850/SC3)
User’s Manual U15109EJ3V0UD
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(a) Read
MOM
Specification of CAN module’s operating mode
0
Normal operating mode
1
Diagnostic processing mode
•
When in diagnostic processing mode (MOM bit = 1), the CnBRP register can be accessed
only when the CAN module has been set to initialization mode (i.e., when the CnCTRL
register’s ISTAT bit = INIT bit = 1).
When the CAN module is operating (i.e., when the CnCTRL register’s ISTAT bit = 0) the
CnBRP register cannot be used, and the CANn bus diagnostic information register
(CnDINF) register can be used instead.
•
The CAN protocol layer does not sent ACK, error frame, or transmit messages, nor does it
operate an error counter.
The internal transmit output is fed back to the internal input due to auto baud rate
detection.
SSHT
Specification of single shot mode
0
Normal operating mode
1
Single shot mode
•
In single shot mode, the CAN module can transmit a message only once. The M_STATa
(a = 00 to 31) register’s TRQ bit is then cleared (0) regardless of whether or not there are
any pending normal transmit operations.
Also, if a bus error has occurred due to a transmission, it is processed as a transmission
error.
•
In single shot mode, even if the CAN lost in the arbitration phase, it is handled as a
completed message transmission.
In this mode, the BERR bit is set (1) but the error counter (see
19.5.22 CANn error count
register (CnERC)
) value does not change since there are no CAN bus errors.
•
In single shot mode, even when transmission is stopped due to error detection or a loss in
the arbitration phase, the transmission completion interrupt occurs.
•
During the time when the CAN module is active, normal operating mode and single shot
mode can be switched without causing any errors on the CAN bus.
PBB
Specification of priority control for transmission
0
Identifier (ID) based priority control
1
Message number based priority control
•
Ordinarily, priority for transmission is defined based on message IDs, but when the PBB
bit has been set (1) priority becomes based instead on the position of messages, so that
messages with lower message numbers have higher priority.
BERR
CAN bus error status
0
CAN bus error was not detected
1
CAN bus error was detected at least once after bit was cleared
VALID
Valid message detection status
0
Valid message was not detected
1
Valid message was detected at least once after bit was cleared