SN8P1700
8-bit micro-controller build-in 12-bit ADC
WAKEUP TIME
OVERVIEW
The external high-speed oscillator needs a delay time from stopping to operating. The delay is very necessary and
makes the oscillator to work stably. Some conditions during system operating, the external high-speed oscillator often
runs and stops. Under these condition, the delay time for external high-speed oscillator restart is called wakeup time.
There are two conditions need wakeup time. One is power down mode to normal mode. The other one is slow mode to
normal mode. For the first case, SN8P1700 provides 2048 oscillator clocks to be the wakeup time. But in the last case,
users need to make the wakeup time by themselves.
HARDWARE WAKEUP
When the system is in power down mode (sleep mode), the external high-speed oscillator stops. For wakeup into
normal, SN8P1700 provides 2048 external high-speed oscillator clocks to be the wakeup time for warming up the
oscillator circuit. After the wakeup time, the system goes into the normal mode. The value of the wakeup time is as
following.
The wakeup time = 1/Fosc * 2048 (sec)
ꢃExample: In power down mode (sleep mode), the system is waked up by P0 or P1 trigger signal. After the
wakeup time, the system goes into normal mode. The wakeup time of P0, P1 wakeup function is
as following.
The wakeup time = 1/Fosc * 2048 = 0.57 ms
The wakeup time = 1/Fosc * 2048 = 62.5 ms
(Fosc = 3.58MHz)
(Fosc=32768Hz)
Under power down mode (sleep mode), there are only I/O ports with wakeup function making the system to return
normal mode. The Port 0 and Port 1 have wakeup function. Port 0’s wakeup function always enables. The Port 1
controls by the P1W register.
P1W initial value = xx00 0000
0C0H
P1W
Bit 7
0
-
Bit 6
0
-
Bit 5
P15W
W
Bit 4
P14W
W
Bit 3
P13W
W
Bit 2
P12W
W
Bit 1
P11W
W
Bit 0
P10W
W
P10W~P15W: Port 1 wakeup function control bits. 0 = none wakeup function, 1 = Enable each pin of Port 1 wakeup
function.
ꢂNote: For SN8P1702 the P1W register only obtains P10W and P11W. For SN8P1704 the P1W register only
obtain P10W~P14W.
SONiX TECHNOLOGY CO., LTD
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Revision 1.94
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