SH79F166APSLASH044PR datasheet(28/113 Pages) SINOWEALTH

28 / 113 page

SH79F166A

7.5 System Clock and Oscillator

7.5.1 Features

 Four oscillator types: 32.768kHz crystal, crystal oscillator, ceramic oscillator and 12MHz/128kHz internal RC

 4 Oscillator pin (XTAL1, XTAL2, XTALX1, XTALX2)

 Built-in 12MHz Internal RC

 Built-in 32.768kHz speed up circuit

 Built-in system clock prescaler

7.5.2 Clock Definition

The SH79F166A have several internal clocks defined as below:

OSCCLK: the oscillator clock from one of the four oscillator types (32.768kHz crystal oscillator, crystal oscillator，ceramic

oscillator and interal RC) fOSC is defined as the OSCCLK frequency. tOSC is defined as the OSCCLK period.

OSCXCLK: the oscillator clock from one of the three oscillator types (crystal oscillator, ceramic oscillator and interal RC) fOSCx

is defined as the OSCXCLK frequency. tOSCX is defined as the OSCXCLK period.

Note: OSCXCLK does not exist when code option OP_OSC is not 0011, 0110, 1010, 1101. (32.768kHz oscillator/128kHz

internal RC is not selected, Refer to code option section for details)

WDTCLK: the internal WDT RC clock. fWDT is defined as the WDTCLK frequency. tWDT is defined as the WDTCLK period.

OSCSCLK: the input of system clock prescaler. It can be OSCCLK or OSCXCLK. fOSCS is defined as the OSCSCLK frequency.

tOSCS is defined as the OSCSCLK period.

SYSCLK: system clock, the output of system clock prescaler. It is the CPU instruction clock. fSYS is defined as the SYSCLK

frequency. tSYS is defined as the SYSCLK period.

7.5.3 Description

SH79F166A has four oscillator types: 32.768kHz crystal oscillator, crystal oscillator (2MHz-12MHz), ceramic Oscillator

(2MHz-12MHz) and internal RC (12MHz,), which is selected by code option OP_OSC (Refer to code option section for details).

SH79F166A have 4 Oscillator pin (XTAL1, XTAL2, XTALX1, XTALX2) and can generates one or two clock sources from four

oscillator types. It is selected by code option OP_OSC (Refer to code option section for details). The oscillator generates the

basic clock pulse that provides the system clock to supply CPU and on-chip peripherals.

SH79F166AP/044PR Datasheet(PDF) 28 Page - SINOWEALTH Electronic Ltd