Functional Description and Application Information
Wake-up / Cyclic Sense
MM912F634
Freescale Semiconductor
74
4.8.1.2
Lx - Cyclic Sense Wake-up
NOTE
Once Cyclic Sense is configured (CSSEL!=0), the state change is only recognized from one
cyclic sense event to the next.
The additional accuracy of the cyclic sense cycle by the WD clock trimming is only active
during STOP mode. There is no trimmed clock available during SLEEP mode.
To reduce external power consumption during low power mode a cyclic wake-up has been implemented. Configuring the Timing
Control Register (TCR) a specific cycle time can be selected to implement a periodic switching of the HS1 or HS2 output with the
corresponding detection of an Lx state change. Any configuration of the HSx in the High Side Control Register (HSCR) will be
ignored when entering low power mode. The Lx - Cyclic Sense Wake-up may be combined with the Forced Wake-up. In case
both (forced and Lx change) events are present at the same time, the Forced Wake-up will be indicated as Wake-up source.
4.8.1.3
Forced Wake-up
Configuring the Forced Wake-up Multiplier (FWM) in the Timing Control Register (TCR) will enable the forced wake-up based on
the selected Cyclic Sense Timing (CST). Forced Wake-up can be combined with all other wake-up sources considering the timing
dependencies.
4.8.1.4
LIN - Wake-up
While in Low-Power mode the MM912F634 analog die monitors the activity on the LIN bus. A dominant pulse longer than
tPROPWL followed by a dominant to recessive transition will cause a LIN Wake-up. This behavior protects the system from a
short-to-ground bus condition.
4.8.1.5
D2D - Wake-up (Stop Mode only)
Receiving a Normal mode request via the D2D interface (MODE=0, Mode Control Register (MCR)) will result in a wake-up from
stop mode. As this condition is controlled by the MCU, no wake-up status bit does indicate this wake-up source.
4.8.1.6
Wake-up Due to Internal / External Reset (STOP Mode Only)
While in Stop mode, a Reset due to a VDD low voltage condition or an external Reset applied on the RESET_A pin will result in
a Wake-up with immediate transition to Reset mode. In this case, the LVR or EXR bits in the Reset Status Register will indicate
the source of the event.
4.8.1.7
Wake-up Due to Loss of Supply Voltage (SLEEP Mode Only)
While in Sleep mode, a supply voltage VS1 < VPOR will result in a transition to Power On mode.