M68HC05 datasheet(39/302 Pages) FREESCALE

39 / 302 page

MC68HC05B6

Rev. 4.1

Freescale

2-11

MODES OF OPERATION AND PIN DESCRIPTIONS

2.5.5

TCAP2

The TCAP2 input controls the input capture 2 function of the on-chip programmable timer system.

2.5.6

TCMP1

The TCMP1 pin is the output of the output compare 1 function of the timer system.

2.5.7

TCMP2

The TCMP2 pin is the output of the output compare 2 function of the timer system.

2.5.8

OSC1, OSC2

These pins provide control input for an on-chip oscillator circuit. A crystal, ceramic resonator or

external clock signal connected to these pins supplies the oscillator clock. The oscillator frequency

(fOSC) is divided by two to give the internal bus frequency (fOP). There is also a software option

which introduces an additional divide by 16 into the oscillator clock, giving an internal bus

frequency of fOSC/32.

2.5.8.1

Crystal

The circuit shown in Figure 2-5(a) is recommended when using either a crystal or a ceramic

resonator. Figure 2-5(d) lists the recommended capacitance and feedback resistance values. The

internal oscillator is designed to interface with an AT-cut parallel-resonant quartz crystal resonator

in the frequency range specified for fOSC (see Section 11.4). Use of an external CMOS oscillator

is recommended when crystals outside the specified ranges are to be used. The crystal and

associated components should be mounted as close as possible to the input pins to minimise

output distortion and start-up stabilisation time. The manufacturer of the particular crystal being

considered should be consulted for specific information.

2.5.8.2

Ceramic resonator

A ceramic resonator may be used instead of a crystal in cost sensitive applications. The circuit shown

in Figure 2-5(a) is recommended when using either a crystal or a ceramic resonator. Figure 2-5(d)

lists the recommended capacitance and feedback resistance values. The manufacturer of the

particular ceramic resonator being considered should be consulted for specific information.

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