3.6 OSCILLATOR CONFIGURATION

This device supports four oscillator modes. Users can program two configuration bits to select the appropriate

mode. These oscillator modes offered as:

• RC: Low-cost crystal

• XTAL: Standard crystal oscillator

• HFXTAL: High frequency crystal oscillator

• LFXTAL: Low frequency crystal oscillator

3.6.1 XTAL, HFXTAL or LFXTAL modes

3.6.2 RC Oscillator Mode

3.7 CONFIGURATION WORD

CTM8B54E/55E/56E/57E

Internal

Circuit

SLEEP

RF

RS

XTAL

(a) Crystal Operation (or Ceramic Resonator)

OSCI

OSCO

(b) External Clock Input Operation

CTM8B54E/55E/56E/57E

OSCI

OSCO

Open

Clock from

external system

CTM8B54E/55E/56E/57E

OSCI

OSCO

0

4

÷

R

C

internal

clock

Bit 3

Code Protect

Bit2

WDT Enable

Bit1

Oscillator Type

Bit0

Oscillator Type

Function

Remark

1

0

x

x

x

x

x

x

EPROM unprotected

EPROM protected

Default

x

x

1

0

x

x

x

x

Watchdog Timer enable

Watchdog Timer disable

Default

x

x

x

x

x

x

x

x

1

1

0

0

1

0

1

0

RC

HFXTAL

XTAL

LFXTAL

Default

CMOS Microcontroller

EPROM-Based 8-Bit

CTM8B54E/55E/56E/57E

* All specs and applications shown above subject to change without prior notice.

1F-5 NO.66 SEC.2 NAN-KAN RD ., LUCHU , TAOYUAN, TAIWAN, R.O.C

Email: server@ceramate.com.tw

Tel:886-3-3529445

Http: www.ceramate.com.tw

Fax:886-3-3521052

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Rev 1.1 Dec 26,2001