NEC UPD703116 User Manual page 581

(a) Read (2/3)
Bit position Bit name
6 MOM
5 SSHT
4 PBB
3 BERR
2 VALID
CHAPTER 11 FCAN CONTROLLER
Specifies the CAN module operation mode.
0: Normal operating mode
1: Diagnostic processing mode
Cautions 1. When in diagnostic processing mode (MOM bit = 1), the C1BRP register
can be accessed only when the CAN module has been set to
initialization mode (i.e., when the C1CTRL register's ISTAT bit = INIT bit
= 1).
When the CAN module is operating (i.e., when the C1CTRL register's
ISTAT bit = 0), the C1BRP register cannot be used, and the CAN1 bus
diagnostic information register (refer to 11. 10 (27) CAN1 bus
diagnostic information register (C1DINF)) can be used instead.
2. The CAN protocol layer does not send 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.
Specifies single shot mode.
0: Normal operating mode
1: Single shot mode
In single shot mode, the CAN module can transmit a message only one time. The
M_STATn register's TRQ bit is then cleared (to 0) regardless of whether or not there are
any pending normal transmit operations (n = 00 to 31).
Also, if a bus error has occurred due to a transmission, it is handled as an incomplete
transmission.
Cautions 1. In single shot mode, even if the CAN lost in arbitration, it is handled as
a completed message transmission.
When in this mode, the BERR bit is set (to 1) but the error counter
value (refer to 11.10 (23) CAN1 error count register (C1ERC)) does not
change since there are no CAN bus errors.
2. 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.
3. During the time when the CAN module is active, the CPU switches
between normal operation mode and single shot mode without causing
any errors to occur on the CAN bus.
Specifies 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 (to 1) priority becomes based instead on the position of messages, so that
messages with lower message numbers have higher priority.
Indicates CAN bus error status.
0: CAN bus error was not detected
1: CAN bus error was detected at least once after bit was cleared
Indicates valid message detection status.
0: Valid message was not detected
1: Valid message was detected at least once after bit was cleared
User's Manual U14492EJ5V0UD
Function
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