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Sunday 22 June 2014

Circuit to Connect External Crystal Oscillator to ATMega328

by realfinetime  |  in ATmega328 at  10:49

Oscillator is an important component for all devices, which works based on clock frequency. In general oscillators are used to generate clock signals. Apart from these, if you want to use ATMega328 microcontroller that programmed using Arduino Board, on a circuit without using Arduino board, an external crystal oscillator of 16MHz should be connected. Clock signals generally changes between two states. Transition between these two states is very short and is called Edge.

Purpose of Clock in Microcontroller.
1. Helps all parts of microcontroller to work together.
2. By increasing the Clock speed, we can increase the speed of micrcontroller.
3. Parts of microcontroller is made of components that changes their state at Edges of the Clock Pulses.     By knowing the frequency of oscillator and the number of clock pulses that each operation needed to     accompolish, we can easily predict, "Which operation will take place at a particular clock cycle".
ATMega ICs have a built in 1 MHz oscillator. By increasing the Oscillator speed, we can increase the speed of the microcontroller operations. External oscillator is normally connected to the XTAL pins ( Pin 9 and Pin 10 ) of ATmega Microcontrollers. 

External crystal oscillator is connected to the microcontroller as shown in the following circuit diagram. Oscillator connected here is a 16MHz oscillator. If the capacitors are not connected as shown in figure, Crystal oscillator will not oscillate properly.
If all goes well, then your microcontroller will work on 16MHz. 


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All the circuits, published in this blog is only after testing and getting proper results in my private lab. When you try these circuits, you should check the supply voltage, polarity of components, presence of childrens nearby and shorts in the circuits. This website will not be responsible for any harm happened to you or your components caused by your carelessness.

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