Why you use crystal oscillator in 8085 microprocessor?

Answer 1

The oscillator provides the basic clock of a microcontroller to be able to execute the instructions in a stable, periodic way. It is often used for other peripherals too, like timer, UART, etc. as frequency base, usually divided by a clock divider for integer factors, or by PLL for rational factors.

If the timing accuracy of these functions is not important, a simple RC oscillator can be used. Many microcontrollers have it internally. Accuracy is in 1...10% range. For better accuracy and temperature stability, a resonator can be used. For applications where timing is critical, a crystal can be used. Most micros have built-in oscillator, so only a crystal and two caps are needed. For those which have no built-in oscillator, external crystal oscillator module may be used. There are OCXO and TCXO modules available for very high stability needs.

Answer 2

Crystal oscillators are piezeoelectric materials since they works on the principle of piezeoelectric effect. piezeo means squeeze or press .This effect states that electric charge accumulates when a pressure or mechanical stress is given. Crystal oscillator is the most used oscillator in digital circuits, Because of the following advantages when compared with Hartley and colpitts oscillator.

1.Stable at high temperatures

2.High frequency response

3.Good resonance

4.High frequency stability

5.More oscillations are produced

6.good resonating or operating frequency

crystal oscillator gives desired frequency of oscillations for given bias voltage, since, Digital circuits works on clock pulse signals so crystal oscillator suits for this applications.crystal oscillator has wide range of applications.Depending up on type of applications type of crystal changes in the oscillator circuit.There are three types of crystal used in oscillators.They are:

1. Rochelle salt crystal

2. Tourmaline crystal

3. Quartz crystal

This type of crystal differs in there characteristics i.e.,

1.Mechanical strength

2.Frequency of oscillations

Here different crystal have different resonating frequency.

Among this crystals quartz crystal have moderate or optimum characteristics

while Rochelle salt crystal has less mechanical strength and output is good

and it is vice versa for tourmaline crystal.output is AC in crystal oscillators.

In this way each crystal has there own Applications.

Eg:-signal generators,oscilloscopes, electronic gadgets like computers,digital watches, calculators,radios,cellphones etc.

Answer 3

its to oscillate a vibration and passes a signal to the processor

Answer 4

for accurate time

rc oscillator is common in non time critical stuff