SN8A1702AS datasheet(67/145 Pages) SONIX

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SN8P1700

8-bit micro-controller build-in 12-bit ADC

SONiX TECHNOLOGY CO., LTD

Page 67

Revision 1.94

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)

Example: 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

(Fosc = 3.58MHz)

The wakeup time = 1/Fosc * 2048 = 62.5 ms

(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

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

P1W

P15W

P14W

P13W

P12W

P11W

P10W

P10W~P15W: Port 1 wakeup function control bits. 0 = none wakeup function, 1 = Enable each pin of Port 1 wakeup

function.

Note: For SN8P1702 the P1W register only obtains P10W and P11W. For SN8P1704 the P1W register only

obtain P10W~P14W.

SN8A1702AS Datasheet(PDF) 67 Page - SONiX Technology Company

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