PIC16F753 datasheet(54/230 Pages) MICROCHIP

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PIC16F753/HV753

DS40001709C-page 54

 2013-2015 Microchip Technology Inc.

6.0

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

Figure 6-1 is a block diagram of the Timer0 module.

6.1

Timer0 Operation

When used as a timer, the Timer0 module can be used

as either an 8-bit timer or an 8-bit counter.

6.1.1

8-BIT TIMER MODE

When used as a timer, the Timer0 module will

increment every instruction cycle (without prescaler).

Timer mode is selected by clearing the T0CS bit of the

OPTION register to ‘0’.

When TMR0 is written, the increment is inhibited for

two instruction cycles immediately following the write.

6.1.2

8-BIT COUNTER MODE

When used as a counter, the Timer0 module will

increment on every rising or falling edge of the T0CKI

pin. The incrementing edge is determined by the T0SE

bit of the OPTION_REG register. Counter mode is

selected by setting the T0CS bit of the OPTION register

to ‘1’.

FIGURE 6-1:

TIMER0 WITH SHARED PRESCALE BLOCK DIAGRAM

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

Watchdog

Timer

WDT

Time-out

PS<2:0>

Data Bus

Set Flag bit T0IF

on Overflow

T0CS

Note 1:

T0SE, T0CS, PSA, PS<2:0> are bits in Register 6-1.

WDTE bit is in Register 19-1.

8-bit

Prescaler

FOSC/4

PSA

Sync

2 TCY

Shared Prescale

WDTE

LFINTOSC

(Figure 4-1)

2

PSA

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