mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 474

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

Chapter 10 Freescale’s Scalable Controller Area Network (S12MSCANV3)
(CANTFLG).” Interrupts are pending as long as one of the corresponding flags is set. The flags in
CANRFLG and CANTFLG must be reset within the interrupt handler to handshake the interrupt. The flags
are reset by writing a 1 to the corresponding bit position. A flag cannot be cleared if the respective
condition prevails.
10.4.7.7
The MSCAN can recover from stop or wait via the wake-up interrupt. This interrupt can only occur if the
MSCAN was in sleep mode (SLPRQ = 1 and SLPAK = 1) before entering power down mode, the wake-up
option is enabled (WUPE = 1), and the wake-up interrupt is enabled (WUPIE = 1).
10.5
10.5.1
The procedure to initially start up the MSCAN module out of reset is as follows:
If the configuration of registers which are writable in initialization mode needs to be changed only when
the MSCAN module is in normal mode:
10.5.2
The bus-off recovery is user configurable. The bus-off state can either be left automatically or on user
request.
For reasons of backwards compatibility, the MSCAN defaults to automatic recovery after reset. In this
case, the MSCAN will become error active again after counting 128 occurrences of 11 consecutive
recessive bits on the CAN bus (See the Bosch CAN specification for details).
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1. Assert CANE
2. Write to the configuration registers in initialization mode
3. Clear INITRQ to leave initialization mode and enter normal mode
1. Bring the module into sleep mode by setting SLPRQ and awaiting SLPAK to assert after the CAN
2. Enter initialization mode: assert INITRQ and await INITAK
3. Write to the configuration registers in initialization mode
4. Clear INITRQ to leave initialization mode and continue in normal mode
bus becomes idle.
Initialization/Application Information
MSCAN initialization
Bus-Off Recovery
Recovery from Stop or Wait
It must be guaranteed that the CPU clears only the bit causing the current
interrupt. For this reason, bit manipulation instructions (BSET) must not be
used to clear interrupt flags. These instructions may cause accidental
clearing of interrupt flags which are set after entering the current interrupt
service routine.
MC9S12XDP512 Data Sheet, Rev. 2.17
NOTE
Freescale Semiconductor