# Clock ?

Discussion in 'Electronic Basics' started by Sriram, Aug 29, 2003.

1. ### SriramGuest

Hi,
What is a Clock ?.
Why do we need a clock in a circuit ?.

What is meant by "driving the circuit" ?.

Do we need a clock only to get an interrupt ?.

Thanks,

Sriram

2. ### Dana RaymondGuest

What is a Clock ?.
A Clock is used in a digital circuit to coordinate different parts to
operate in a synchronized manner, almost like a mentronome sets the timing
of a piece of music. The metronome 'ticks' at regular intervals, and each
note or notes need to start at the tick and to be done before the end of the
tick. This prevents the notes from running into each other.

Likewise, each part of a circuit must start working when the clock signal
rises (or sometimes when it falls) and must finish its job before the next
clock 'tick'. Since digital circuitry usually has one part feeding into the
next one, the clock is connected to both parts and ensures that the second
one waits for the first to finish before doing its job.

The digital circuitry is very much like an assembly line, and the clock
keeps every part working in time. If you increase the rate of the metronome
the music plays faster. Likewise, increasing the clock frequency increases
the speed of the circuit - however each part must be able to complete its
job in the time allotted or mayhem will ensue.
That usually means that one circuit of some sort is connected to the next
one, its OUTPUT driving the next one's INPUT.
Thw two are not related at all, except that anything that will accept an
interrupt and do something with it usually has a clock for it to work.

Hope this helps.
Dana Frank Raymond