25-18
MCF5282 User’s Manual
MOTOROLA
Functional Overview
To exit low-power stop mode:
• Reset the FlexCAN either by asserting RSTI or by setting the SOFTRST bit
CANMCR.
• Clear the STOP bit in CANMCR.
• The FlexCAN 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 FlexCAN
entered stop mode, then upon detection of a recessive to dominant transition on the
CAN bus, the FlexCAN clears the STOP bit in CANMCR and its clocks begin
running.
When 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 can generate
an interrupt if the WAKEMSK bit in CANMCR is set.
Consider the following notes regarding low-power stop mode:
• When the self-wake mechanism activates, the FlexCAN tries to receive the frame
that woke it up. (It assumes that the dominant bit detected is a start-of-frame bit). It
will not arbitrate for the CAN bus at this time.
• The CPU should disable all interrupts in the FlexCAN before entering low-power
stop mode. Otherwise it may be interrupted while in STOP mode upon a non
wake-up condition; If desired, the WAKEMASK bit should be set to enable the
WAKEINT.
• If the STOP bit is set while the FlexCAN is in the bus off state, then the FlexCAN
will enter low-power stop mode and stop counting recessive bit times. The count
will continue when STOP is cleared.
• To place the FlexCAN in low-power stop mode with the self-wake mechanism
engaged, write to CANMCR with both STOP and SELFWAKE set, then wait for the
FlexCAN to set the STOPACK bit.
• To take the FlexCAN out of low-power stop mode when the self-wake mechanism
is enabled, write to CANMCR with both STOP and SELFWAKE clear, then wait for
the FlexCAN to clear the STOPACK bit.
• The SELFWAKE bit should not be set after the FlexCAN has already entered
low-power stop mode.
• If both STOP and SELFWAKE are set and a recessive to dominant edge
immediately occurs on the CAN bus, the FlexCAN may never set the STOPACK bit,
and the STOP bit will be cleared.
• To prevent old frames from being sent when the FlexCAN awakes from low-power
stop mode via the self-wake mechanism, disable all transmit sources, including
transmit buffers configured for remote request responses, before placing the
FlexCAN in low-power stop mode.
Summary of Contents for ColdFire MCF5281
Page 124: ...3 20 MCF5282 User s Manual MOTOROLA EMAC Instruction Set Summary ...
Page 141: ...MOTOROLA Chapter 5 Static RAM SRAM 5 5 SRAM Programming Model ...
Page 142: ...5 6 MCF5282 User s Manual MOTOROLA SRAM Programming Model ...
Page 168: ...6 26 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 186: ...7 18 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 228: ...9 22 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 246: ...10 18 MCF5282 User s Manual MOTOROLA Low Power Wakeup Operation ...
Page 254: ...11 8 MCF5282 User s Manual MOTOROLA Memory Map and Registers ...
Page 264: ...12 10 MCF5282 User s Manual MOTOROLA Chip Select Registers ...
Page 280: ...13 16 MCF5282 User s Manual MOTOROLA Misaligned Operands ...
Page 314: ...14 34 MCF5282 User s Manual MOTOROLA MCF5282 External Signals ...
Page 339: ...MOTOROLA Chapter 15 Synchronous DRAM Controller Module 15 25 SDRAM Example ...
Page 340: ...15 26 MCF5282 User s Manual MOTOROLA SDRAM Example ...
Page 356: ...16 16 MCF5282 User s Manual MOTOROLA DMA Controller Module Functional Description ...
Page 408: ...17 52 MCF5282 User s Manual MOTOROLA Buffer Descriptors ...
Page 446: ...20 24 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 474: ...22 18 MCF5282 User s Manual MOTOROLA Programming Model ...
Page 510: ...23 36 MCF5282 User s Manual MOTOROLA Operation ...
Page 526: ...24 16 MCF5282 User s Manual MOTOROLA I2C Programming Examples ...
Page 672: ...28 12 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 718: ...29 46 MCF5282 User s Manual MOTOROLA Motorola Recommended BDM Pinout ...
Page 750: ...32 8 MCF5282 User s Manual MOTOROLA Ordering Information ...