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M16C/5L Group, M16C/56 Group
23.2.2
CAN Halt Mode
CAN halt mode is used for mailbox configuration and test mode setting.
When the CANM bit in the C0CTLR register is set to 10b, CAN halt mode is selected. Then the HLTST
bit in the C0STR register is set to 1. Do not change the CANM bit until the HLTST bit is set to 1.
Refer to Table 23.9 Operation in CAN Reset Mode and CAN Halt Mode regarding the state transition
conditions when transmitting or receiving.
All registers except bits RSTST, HLTST, and SLPST in the C0STR register remain unchanged when the
CAN module enters CAN halt mode.
Do not change registers C0 CLKR, C0 CTLR (except bits CANM and SLPM,) and C0EIER in CAN halt
mode. The C0BCR register can be changed in CAN halt mode only when listen-only mode is selected
to use for automatic bit rate detection.
Table 23.9
Operation in CAN Reset Mode and CAN Halt Mode
Mode
CAN module enters CAN reset
CAN reset
mode without waiting for the end
mode
of message reception.
CAN halt
CAN module enters CAN halt
mode
mode after waiting for the end of
message reception.
BOM bit: Bit in the C0CTLR register
Notes:
1.
If several messages are requested to be transmitted, mode transition occurs after the completion of
the first transmission. In a case that the CAN reset mode is being requested during suspend
transmission, mode transition occurs when the bus is idle, the next transmission ends, or the CAN
module becomes a receiver.
2.
If the CAN bus is locked at the dominant level, the program can detect this state by monitoring the
BLIF bit in the C0EIFR register.
3.
If a CAN bus error occurs during reception after CAN halt mode is requested, the CAN mode transits
to CAN halt mode.
4.
If a CAN bus error or arbitration lost occurs during transmission after CAN reset mode or CAN halt
mode is requested, the CAN mode transits to the requested CAN mode.
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
Receiver
CAN module enters CAN reset
mode after waiting for the end of
message transmission.
CAN module enters CAN halt
mode after waiting for the end of
(2, 3)
message transmission.
Transmitter
CAN module enters CAN reset
mode without waiting for the end
(1, 4)
of bus-off recovery.
[When the BOM bit is 00b]
A halt request from a program
will be acknowledged only
after bus-off recovery.
[When the BOM bit is 01b]
CAN module enters
automatically to CAN halt
mode without waiting for the
end of bus-off recovery
(regardless of a halt request
from a program).
[When the BOM bit is 10b]
CAN module enters
(1, 4)
automatically to CAN halt
mode after waiting for the end
of bus-off recovery
(regardless of a halt request
from a program).
[When the BOM bit is 11b]
CAN module enters CAN halt
mode (without waiting for the
end of bus-off recovery) if a
halt is requested by a program
during bus-off.
23. CAN Module
Bus-Off
Page 600 of 803
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