Page 10 - DEC40053 Ebook_Timer

What is Timer?

Clock source can be internal or external

For internal clock, 1/4th of the frequency of

the crystal oscillator on the OSC1 and OSC2

pins (Fosc/4) is fed into the timer.

For external clock, pulses are fed to PIC and

used as counter.

Timers are common features of most

microcontroller.

In simplified terms, a timer is just a register

whose value keeps increasing (or decreasing)

at a constant rate without the help of the

CPU.

The CPU can read or write this register at any

time. It finds out how much time has elapsed.

The timer in PIC18F refers to the hardware timer

inside the PIC18F itself.

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