MC68HC908GZ8 Datasheet, PDF (186/344 Pages) Motorola, Inc – Microcontrollers

MSCAN08 Controller (MSCAN08)
SLPRQ — Sleep Request, Go to Internal Sleep Mode
This flag requests the MSCAN08 to go into an internal power-saving mode (see
16.8.1 MSCAN08 Sleep Mode).
1 = Sleep — The MSCAN08 will go into internal sleep mode.
0 = Wakeup — The MSCAN08 will function normally.
SFTRES — Soft Reset
When this bit is set by the CPU, the MSCAN08 immediately enters the soft reset
state. Any ongoing transmission or reception is aborted and synchronization to
the bus is lost.
The following registers enter and stay in their hard reset state:
CMCR0, CRFLG, CRIER, CTFLG, and CTCR.
The registers CMCR1, CBTR0, CBTR1, CIDAC, CIDAR0–CIDAR3, and
CIDMR0–CIDMR3 can only be written by the CPU when the MSCAN08 is in soft
reset state. The values of the error counters are not affected by soft reset.
When this bit is cleared by the CPU, the MSCAN08 tries to synchronize to the
CAN bus. If the MSCAN08 is not in bus-off state, it will be synchronized after 11
recessive bits on the bus; if the MSCAN08 is in bus-off state, it continues to wait
for 128 occurrences of 11 recessive bits.
Clearing SFTRES and writing to other bits in CMCR0 must be in separate
instructions.
1 = MSCAN08 in soft reset state
0 = Normal operation
16.13.2 MSCAN08 Module Control Register 1
Address:
Read:
Write:
Reset:
$0501
Bit 7
0
0
6
5
4
0
0
0
0
0
0
= Unimplemented
3
2
1
Bit 0
0
LOOPB WUPM CLKSRC
0
0
0
0
Figure 16-16. Module Control Register (CMCR1)
LOOPB — Loop Back Self-Test Mode
When this bit is set, the MSCAN08 performs an internal loop back which can be
used for self-test operation: the bit stream output of the transmitter is fed back
to the receiver internally. The CAN_Rx input pin is ignored and the CAN_Tx output
goes to the recessive state (logic 1). The MSCAN08 behaves as it does
normally when transmitting and treats its own transmitted message as a
message received from a remote node. In this state the MSCAN08 ignores the
bit sent during the ACK slot of the CAN frame Acknowledge field to insure
proper reception of its own message. Both transmit and receive interrupts are
generated.
1 = Activate loop back self-test mode
0 = Normal operation
Data Sheet
186
MSCAN08 Controller (MSCAN08)
MC68HC908GZ8
Freescale Semiconductor