CAN 2.0B Controller Module
MPC561/MPC563 Reference Manual, Rev. 1.2
16-18
Freescale Semiconductor
•
The TouCAN stops transmitting or receiving frames
•
The prescaler is disabled, thus halting all CAN bus communication
•
The TouCAN ignores its Rx signals and drives its Tx signals as recessive
•
The TouCAN loses synchronization with the CAN bus and the NOTRDY and FRZACK bits in
CANMCR are set
•
The CPU is allowed to read and write the error counter registers
After engaging one of the mechanisms to place the TouCAN in debug mode, the FRZACK bit must be set
before accessing any other registers in the TouCAN; otherwise unpredictable operation may occur.
To exit debug mode, the IMB3 FREEZE line must be negated or the HALT bit in CANMCR must be
cleared.
Once debug mode is exited, the TouCAN resynchronizes with the CAN bus by waiting for 11 consecutive
recessive bits before beginning to participate in CAN bus communication.
16.5.2
Low-Power Stop Mode
Before entering low-power stop mode, the TouCAN waits for the CAN bus to be in an idle state, or for the
third bit of intermission to be recessive. The TouCAN then waits for the completion of all internal activity
(except in the CAN bus interface) to be complete. Then the following events occur:
•
The TouCAN shuts down its clocks, stopping most internal circuits, thus achieving maximum
power savings
•
The bus interface unit continues to operate, allowing the CPU to access the module configuration
register
•
The TouCAN ignores its Rx signals and drives its Tx signals as recessive
•
The TouCAN loses synchronization with the CAN bus, and the STOPACK and NOTRDY bits in
the module configuration register are set
To exit low-power stop mode:
•
Reset the TouCAN either by asserting one of the IMB3 reset lines or by asserting the SOFTRST
bit CANMCR
•
Clear the STOP bit in CANMCR
•
The TouCAN module can optionally exit low-power stop mode via the self wake mechanism. If
the SELFWAKE bit in CANMCR was set at the time the TouCAN entered stop mode, then upon
detection of a recessive to dominant transition on the CAN bus, the TouCAN clears the STOP bit
in CANMCR and its clocks begin running.
When the TouCAN is in low-power stop mode, a recessive to dominant transition on the CAN bus causes
the WAKEINT bit in the error and status register (ESTAT) to be set. This event generates an interrupt if
the WAKEMSK bit in CANMCR is set.
Consider the following notes regarding low-power stop mode:
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...