XC2200 Derivatives
System Units (Vol. 1 of 2)
System Control Unit (SCU)
User’s Manual
6-44
V2.1, 2008-08
SCU, V1.13
6.2
Wake-up Timer (WUT)
The Wake-up Timer provides a very compact (and, therefore, power-saving) mean of re-
activating the system from certain power saving modes automatically after a specific
period of time.
The master clock
f
SYS
is prescaled and drives a simple counter. All functions are
Note: For wake-up operation from a power-saving mode the master clock
f
SYS
is usually
derived from the trimmed current controlled wake-up clock
f
WU
.
Figure 6-14 Wake-up Timer Logic
6.2.1
Wake-up Timer Operation
The Wake-up Timer start and stop is controlled by the Run Control logic. The timer can
be started in the following ways:
•
bit WUCR.AON is set AND the Power State Controller (PSC, see
generates a start trigger
•
bit WUCR.RUN is set
When the timer is started the prescaler is reset and the counter WIC starts to count
down.
WUT_MR.vsd
Sync.
f
SYS
WIC
WUCR.
WUTRG
Trim
Interrupt
Trigger
Wake-up
Interrupt
Trigger
f
WU
Run
Control
WUCR.
AONCON
WUCR.
ASPCON
WUCR.
TTSTAT
Wake-Up Timer
WUCR.
RUNCON
run
Wake-up
Trigger
OSC_WU
CGU
64:1
reset
To
PSC,
CCU60
From
PSC
PSC
Control