mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 470

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 10 Freescale’s Scalable Controller Area Network (S12MSCANV3)
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.
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.
10.4.5.5
In initialization mode, any on-going transmission or reception is immediately aborted and synchronization
to the CAN bus is lost, potentially causing CAN protocol violations. To protect the CAN bus system from
fatal consequences of violations, the MSCAN immediately drives the TXCAN pin into a recessive state.
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or
the CPU clears the SLPRQ bit
MSCAN Initialization Mode
The CPU cannot clear the SLPRQ bit before sleep mode (SLPRQ = 1 and
SLPAK = 1) is active.
Figure 10-46. Simplified State Transitions for Entering/Leaving Sleep Mode
StartUp
CAN Activity &
SLPRQ
CAN Activity &
SLPRQ
CAN Activity
MC9S12XDP512 Data Sheet, Rev. 2.17
CAN Activity
CAN Activity
Message
Active
for Idle
Tx/Rx
Wait
Idle
NOTE
SLPRQ
CAN Activity
(CAN Activity & WUPE) | SLPRQ
Sleep
(CAN Activity & WUPE) |
CAN Activity
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