PIC17C42AT-25I/JW View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC17C42AT-25I/JW

High-Performance 8-Bit CMOS EPROM/ROM Microcontroller

Microchip Technology 

11.0 TIMER0

The Timer0 module consists of a 16-bit timer/counter,

TMR0. The high byte is TMR0H and the low byte is

TMR0L. A software programmable 8-bit prescaler

makes an effective 24-bit overflow timer. The clock

source is also software programmable as either the

internal instruction clock or the RA1/T0CKI pin. The

control bits for this module are in register T0STA

(Figure 11-1).

PIC17C4X

FIGURE 11-1: T0STA REGISTER (ADDRESS: 05h, UNBANKED)

R/W - 0

INTEDG

bit7

R/W - 0

T0SE

R/W - 0

T0CS

R/W - 0

PS3

R/W - 0

PS2

R/W - 0

PS1

R/W - 0

PS0

bit 7:

INTEDG: RA0/INT Pin Interrupt Edge Select bit

This bit selects the edge upon which the interrupt is detected

1 = Rising edge of RA0/INT pin generates interrupt

0 = Falling edge of RA0/INT pin generates interrupt

U-0

—

bit0

R = Readable bit

W = Writable bit

U = Unimplemented,

Read as '0'

-n = Value at POR reset

bit 6:

T0SE: Timer0 Clock Input Edge Select bit

This bit selects the edge upon which TMR0 will increment

When T0CS = 0

1 = Rising edge of RA1/T0CKI pin increments TMR0 and/or generates a T0CKIF interrupt

0 = Falling edge of RA1/T0CKI pin increments TMR0 and/or generates a T0CKIF interrupt

When T0CS = 1

Don’t care

bit 5:

T0CS: Timer0 Clock Source Select bit

This bit selects the clock source for TMR0.

1 = Internal instruction clock cycle (TCY)

0 = T0CKI pin

bit 4-1: PS3:PS0: Timer0 Prescale Selection bits

These bits select the prescale value for TMR0.

PS3:PS0

Prescale Value

0000

0001

0010

0011

0100

0101

0110

0111

1xxx

1:1

1:2

1:4

1:8

1:16

1:32

1:64

1:128

1:256

bit 0: Unimplemented: Read as '0'

© 1996 Microchip Technology Inc.

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