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FlexCAN Module
MPC5644A Microcontroller Reference Manual, Rev. 6
1404
Freescale Semiconductor
FEN
FIFO Enable
This bit controls whether the FIFO feature is enabled or not. When FEN is set, MBs 0 to 7 cannot
be used for normal reception and transmission because the corresponding memory region
(0x80–0xFF) is used by the FIFO engine. See
Section 32.4.4, Rx FIFO structure
and
1: FIFO enabled
0: FIFO not enabled
HALT
Halt FlexCAN
Assertion of this bit puts the FlexCAN module into Freeze Mode. The CPU should clear it after
initializing the Message Buffers and Control Register. No reception or transmission is performed
by FlexCAN before this bit is cleared. While in Freeze Mode, the CPU has write access to the Error
Counter Register, that is otherwise read-only. Freeze Mode can not be entered while FlexCAN is
in any of the low power modes. See
1: Enters Freeze Mode if the FRZ bit is asserted.
0: No Freeze Mode request.
NOTRDY
FlexCAN Not Ready
This read-only bit indicates that FlexCAN is either in Disable Mode, Stop Mode or Freeze Mode.
It is negated once FlexCAN has exited these modes.
1: FlexCAN module is either in Disable Mode, Stop Mode or Freeze Mode
0: FlexCAN module is either in Normal Mode, Listen-Only Mode or Loop-Back Mode
WAK_MSK
Wake Up Interrupt Mask
This bit enables the Wake Up Interrupt generation.
1: Wake Up Interrupt is enabled
0: Wake Up Interrupt is disabled
SOFTRST
Soft Reset
When this bit is asserted, FlexCAN resets its internal state machines and some of the memory
mapped registers. The following registers are reset: MCR (except the MDIS bit), TIMER, ECR,
ESR, IMRL, IMRH, IFRL, IFRH. Configuration registers that control the interface to the CAN bus
are not affected by soft reset. The following registers are unaffected:
• CR
• RXIMR0–RXIMR63
• RXGMASK, RX14MASK, RX15MASK
• all Message Buffers
The SOFTRST bit can be asserted directly by the CPU when it writes to the MCR, but it is also
asserted when global soft reset is requested at MCU level. Since soft reset is synchronous and
has to follow a request/acknowledge procedure across clock domains, it may take some time to
fully propagate its effect. The SOFTRST bit remains asserted while reset is pending, and is
automatically negated when reset completes. Therefore, software can poll this bit to know when
the soft reset has completed.
Soft reset cannot be applied while clocks are shut down in any of the low power modes. The
module should be first removed from low power mode, and then soft reset can be applied.
1: Resets the registers marked as “affected by soft reset” in
0: No reset request
Table 32-8. Module Configuration Register (MCR) field descriptions
Field
Description
Summary of Contents for MPC5644A
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