PIC16F720-ESLASHML datasheet(91/244 Pages) MICROCHIP

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 2010 Microchip Technology Inc.

DS41430A-page 91

PIC16F/LF720/721

12.0

TIMER0 MODULE

The Timer0 module is an 8-bit timer/counter with the

following features:

• 8-bit timer/counter register (TMR0)

• 8-bit prescaler (shared with Watchdog Timer)

• Programmable internal or external clock source

• Programmable external clock edge selection

• Interrupt on overflow

• TMR0 can be used to gate Timer1

Figure 12-1 is a block diagram of the Timer0 module.

12.1

Timer0 Operation

The Timer0 module can be used as either an 8-bit timer

or an 8-bit counter.

12.1.1

8-BIT TIMER MODE

The Timer0 module will increment every instruction

cycle, if used without a prescaler. 8-Bit Timer mode is

selected by clearing the T0CS bit of the OPTION

When TMR0 is written, the increment is inhibited for

two instruction cycles immediately following the write.

12.1.2

8-BIT COUNTER MODE

In 8-Bit Counter mode, the Timer0 module will increment

on every rising or falling edge of the T0CKI pin.

8-Bit Counter mode using the T0CKI pin is selected by

setting the T0CS bit in the OPTION register to ‘1’.

The rising or falling transition of the incrementing edge

for either input source is determined by the T0SE bit in

the OPTION register.

FIGURE 12-1:

BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER

Note:

The value written to the TMR0 register

can be adjusted, in order to account for

the two instruction cycle delay when

TMR0 is written.

T0CKI

T0SE

TMR0

WDT

Time-out

PS<2:0>

WDTE

Data Bus

Set Flag bit T0IF

on Overflow

T0CS

8-bit

Prescaler

FOSC/4

PSA

SYNC

2 TCY

Overflow to Timer1

Divide by

512

TMR1GE

T1GSS = 11

Low-Power

WDT OSC

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