SN8F27E64KB datasheet(52/192 Pages) SONIX

52 / 192 page

SN8F27E60 Series

8-Bit Flash Micro-Controller with Embedded ICE and ISP

SONiX TECHNOLOGY CO., LTD

Page 52

Version 1.4

4 SYSTEM CLOCK

4.1 OVERVIEW

The micro-controller is a dual clock system including high-speed and low-speed clocks. The high-speed clock includes

internal high-speed oscillator and external oscillators selected by

“High_CLK” code option. The low-speed clock is from

internal low-speed oscillator controlled by

“CLKMD” bit of OSCM register. Both high-speed clock and low-speed clock

can be system clock source through a divider to decide the system clock rate.



High-speed oscillator

Internal high-speed oscillator is 16MHz RC type called

“IHRC” and “IHRC_RTC”.

External high-speed oscillator includes crystal/ceramic (4MHz, 12MHz, 32KHz) and RC type.



Low-speed oscillator

Internal low-speed oscillator is 16KHz RC type called

“ILRC”.



System clock block diagram

Fhosc.

Fcpu = Fhosc/1 ~ Fhosc/128

Flosc.

Fcpu = Flosc/1 ~ Flosc/8

CPUM[1:0]

XIN

XOUT

STPHX

HOSC

High_Fcpu Code Option

Fosc

CLKMD

Fcpu

Low_Fcpu Code Option



HOSC: High_Clk code option.



Fhosc: External high-speed clock / Internal high-speed RC clock.



Flosc: Internal low-speed RC clock (about 16KHz@3V and @5V).



Fosc: System clock source.



Fcpu: Instruction cycle.

4.2 FCPU (INSTRUCTION CYCLE)

The system clock rate is instruction cycle called

“Fcpu” which is divided from the system clock source and decides the

system operating rate. Fcpu rate is selected by High_Fcpu code option and the range is Fhosc/1~Fhosc/128 under

system normal mode. If the system high clock source is external 4MHz crystal, and the High_Fcpu code option is

Fhosc/4, the Fcpu frequency is 4MHz/4 = 1MHz. Under system slow mode, the Fcpu range is Flosc/1~Flosc/8

controlled by Low_Fcpu code option, If Low_Fcpu code option is Flosc/4, the Fcpu frequency is 16KHz/4=4KHz.

4.3 NOISE FILTER

The Noise Filter controlled by

“Noise_Filter” code option is a low pass filter and supports external oscillator including

RC and crystal modes. The purpose is to filter high rate noise coupling on high clock signal from external oscillator.

In high noisy environment, enable

“Noise_Filter” code option is the strongly recommendation to reduce noise

effect.

4.4 SYSTEM HIGH-SPEED CLOCK

The system high-speed clock has internal and external two-type. The external high-speed clock includes 4MHz, 12MHz,

32KHz crystal/ceramic and RC type. These high-speed oscillators are selected by

“High_CLK” code option. The

internal high-speed clock supports real time clock (RTC) function. Under

“IHRC_RTC” mode, the internal high-speed

clock and external 32KHz oscillator active. The internal high-speed clock is the system clock source, and the external

32KHz oscillator is the RTC clock source to supply a accurately real time clock rate.

SN8F27E64KB Datasheet(PDF) 52 Page - SONiX Technology Company

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