Connection of XTAL1 and XTAL2

Okay this post is little late. But its better late than never. XTAL ports provide clock pulses to the 8051.this can be achieved in 2 ways.

XTAL CONNECTION WITH CRYSTAL

Generally quartz crystal is connected to inputs XTAL1 and XTAL2. This crystal also requires 2 capacitors. One side of each capacitor is connected to the ground. Usually value of capacitor can be 30pF or 33pF. Why capacitor are required in the connection?? Well the answer is directly connected to the basic circuitry of an oscillator.

 

XTAL CONNECTION WITH EXTERNAL OSCILLATOR CIRCUIT

Another way to provide frequency to the microcontroller is through external oscillator circuit. The single output is connected to one of the XTAL port while other is left unconnected. (do not ground the unconnected XTAL port).

 The connection is same way for both microcontroller and microprocessor.