Freescale Semiconductor DEMO9S08DZ60 Demo Board DEMO9S08DZ60 DEMO9S08DZ60 数据表
产品代码
DEMO9S08DZ60
Chapter 12 Freescale’s Controller Area Network (S08MSCANV1)
MC9S08DZ60 Series Data Sheet, Rev. 4
266
Freescale Semiconductor
The MSCAN is able to leave sleep mode (wake up) only when:
•
CAN bus activity occurs and WUPE = 1
or
•
the CPU clears the SLPRQ bit
NOTE
The CPU cannot clear the SLPRQ bit before sleep mode (SLPRQ = 1 and
SLPAK = 1) is active.
SLPAK = 1) is active.
After wake-up, the MSCAN waits for 11 consecutive recessive bits to synchronize to the CAN bus. As a
consequence, if the MSCAN is woken-up by a CAN frame, this frame is not received.
consequence, if the MSCAN is woken-up by a CAN frame, this frame is not received.
The receive message buffers (RxFG and RxBG) contain messages if they were received before sleep mode
was entered. All pending actions will be executed upon wake-up; copying of RxBG into RxFG, message
aborts and message transmissions. If the MSCAN remains in bus-off state after sleep mode was exited, it
continues counting the 128 occurrences of 11 consecutive recessive bits.
was entered. All pending actions will be executed upon wake-up; copying of RxBG into RxFG, message
aborts and message transmissions. If the MSCAN remains in bus-off state after sleep mode was exited, it
continues counting the 128 occurrences of 11 consecutive recessive bits.
Figure 12-45. Simplified State Transitions for Entering/Leaving Sleep Mode
Wait
Idle
Tx/Rx
Message
Active
CAN Activity
CAN Activity &
Sleep
SLPRQ
StartUp
for Idle
(CAN Activity & WUPE) |
(CAN Activity & WUPE) | SLPRQ
CAN Activity
CAN Activity
CAN Activity &
CAN Activity
SLPRQ
SLPRQ
CAN Activity