Why need crystal for microcontroller?

[matramlee]

hi...

im a mechanical student...but im really love to learn about electronic.....

i have some question here.....

if anyone can tell me why do we need crystal for microcontroller??? what is actually the function of the crystal....

and why must we put capacitor to the each end of the crystal?

 

[davenn]

hi there
welcome to the Electronics Point forums

The crystal is the clock oscillator for the microPU. From that osc. the micro does all its timing functions
The 2 capacitors often ~ 20 - 30 pF are just part of the oscillator circuit

Dave

 

[matramlee]

what is actually the function of capacitor?? in what condition will require the capacitor...

 

[Harald Kapp]

Read this application note on crystal oscillators and component selection. It is for PIC microcontrollers but the rules are the same for other chips, too.

 

[KrisBlueNZ]

A quartz crystal is an accurate way to generate a clock frequency. If accuracy is not required, you can also use a ceramic resonator, or an RC (resistor-capacitor) oscillator. Many microcontrollers have a built-in RC oscillator that can be used f high accuracy is not needed; this reduces the number of components needed.