SN8P1602AX datasheet(50/94 Pages) SONIX

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SN8P1600

8-bit micro-controller

SONiX TECHNOLOGY CO., LTD

Page 50

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 work stably. The external high-speed oscillator sometimes starts and stops at different situations.

The delay time for external high-speed oscillator restart is called Wakeup time.

Following are two conditions need Wakeup time. One is switching power down mode to normal mode. The other is

switching slow mode to normal mode. For the first case, SN8P1600 provides 2048 oscillator clocks as the Wakeup

time. The second case, users need to calculate the Wakeup time.

HARDWARE WAKEUP

When the system is in power down mode (sleep mode), the external high-speed oscillator stops. When waked up from

power down mode, MCU waits for 2048 external high-speed oscillator clocks as the Wakeup time to stable the

oscillator circuit. After the Wakeup time, the system goes into the normal mode. The value of the Wakeup time is as the

following.

The Wakeup time = 1/Fosc * 2048 (sec) + X’tal settling time

The x’tal settling time is depended on the x’tal type. Typically, it is about 2~4mS.

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 the

following.

The Wakeup time = 1/Fosc * 2048 = 0.57 ms

(Fosc = 3.58MHz)

The total wakeup time = 0.57ms + x’tal settling time

Under power down mode (sleep mode), there are only I/O ports with Wakeup function wake the system up to normal

mode. The Port 0 and Port 1 have Wakeup function. Port 0 Wakeup function always enables, but the Port 1 is

controlled by the P1W register.

SN8P1602/1603

0C0H

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

P1W

P14W

P13W

P12W

P11W

P10W

Read/Write

R/W

After reset

SN8P1604

0C0H

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

P1W

P17W

P16W

P15W

P14W

P13W

P12W

P11W

P10W

Read/Write

R/W

After reset

P10W~P14W: Port 1 Wakeup function control bits. 0 = none Wakeup function, 1 = Enable Wakeup function.

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