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Analog Integrated Circuit Device Data
Freescale Semiconductor
29
33389
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
Sleep Mode Activation
Once in the Sleep mode, the SBC turns the V1 and V2
regulator OFF . Thus the microcontroller can not run any
mode.
In order to have the microcontroller run again, the SBC
should enable and turn ON V1. This is achieved by an SBC
wake-up event.
Several options are available to wake-up the SBC and the
application and have the microcontroller in Run mode.
Some wake-ups are selectable; some are always active in
Sleep mode:
Wake-up from CAN interface and wake-up from SPI (CS)
are always active.
Wake-up from L0,L1, and L2 inputs, with and without cyclic
sense and the forced wake-up (FWU) are selectable. The
selection must be done while the SBC is in Normal or
Stand-by mode, and prior to enter Sleep mode.
General Condition to Enter Sleep Mode
All previous wake-up conditions must be cleared, assuring
the SBC enters the Sleep mode, and Write operations into
the MCR and MCVR. To clear a wake-up condition requires
reading the appropriate register.
Once the SBC has powered-up from zero (battery power-
up or cold start), the following registers must be read:
WUICR—possible wake-up event report from CAN bus
RSR—report a V1 under voltage
VSSR—reports a VBAT fail flag
Once these read operations are completed, the wake-up
conditions, or flags are reset.
The VBSR0 bit in the VSSR can be used to determine if
the SBC has experienced a loss of battery voltage.
Once the SBC is awakened from Sleep mode the following
registers indicate the wake-up source. They must be cleared
to allow the SBC to enter Sleep mode again:
WUICR—wake-up event report for CAN or SPI buses
WUISR— wake-up event report for the L0,L1, and L2
inputs
RSR—report a V1 under voltage
VSSR—reports a VBAT fail flag
etc.
The ensuing paragraphs describe the write operation to be
accomplished for the several Sleep modes and Wake-up
control options.
In addition to FWU, cyclic sense and direct wake-up, the
CAN and SPI wake will always be activated.
Sleep Mode with CAN and SPI Wake-Up
To enter the Sleep mode and activate the only CAN or SPI
wake-up, there is no dedicated wake-up condition to be
completed. The SBC has CAN and SPI wake-up sources
always active in the Sleep mode. To enter the Sleep mode in
this case, while the SBC is in Normal or Stand-by mode:
Write to V3R—data 0000 (this clears the WI2V3 bit, is set
to1after reset)
Write to MCR—data SLEEP (100)
Write to MCVR—data SLEEP (100)
The SBC then enters the Sleep mode.
Sleep Mode Enter with Forced Wake-Up
To enter the Sleep mode and activate the forced wake-up,
write to the following registers:
Write to V3R (data 0100) this set the FWU bit to 1
Write the desired wake-up time to CYTCR. (This sets the
time the SBC will stay in the Sleep mode).
Write to MCR–data SLEEP (100)
Write to MCVR– data SLEEP (100)
The SBC then enters the Sleep mode. It will wake-up after
the time period is selected in the CYTCR.
Sleep Mode Enter with Cyclic Sense
To enter the Sleep mode and activate the cyclic sense
wake-up the following registers must be written:
Write to V3R (data 1010) this sets the VI2V3 and CYS bits
to 1
Write to CYTCR the desired cyclic sense period. (This sets
the time the SBC will wait in the Sleep mode to turn on V3
and sense the LX inputs)
Write to WUICR bits 0 and 1 to select the edge sensitivity
for the LX inputs
Write to MCR—data SLEEP (100)
Write to MCVR—data SLEEP (100)
The SBC then enters the Sleep mode. It will periodically
turn on V3 and while V3 is on, sample the level of the Ls
inputs.
If any of the 3 LX inputs is in the correct state for two
consecutive samples, SBC will wake-up. If not, it will stay in
the Sleep mode. Refer to device description for detail.
Sleep Mode Enter With Direct LX Input Wake-Up
To enter the Sleep mode and activate the direct wake-up
from the LX inputs, the following registers must be written:
Write to V3R (data 0000) this clear VI2V3 bit
Write to WUICR bits 0 and 1 to select the edge sensitivity
for the LX inputs
Write to MCR—data SLEEP (100)
Write to MCVR—data SLEEP (100)
The SBC then enters the Sleep mode. It will wake-up as
soon as any of the LX input read the correct state.