PIC17C42 Microchip Technology, PIC17C42 Datasheet - Page 67

• Manufacturer Part Number: PIC17C42
• Description: High-Performance 8-Bit CMOS EPROM/ROM Microcontroller
• Manufacturer: Microchip Technology

11.0
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).
FIGURE 11-1: T0STA REGISTER
1996 Microchip Technology Inc.
bit7
bit 7:
bit 6:
bit 5:
bit 4-1: PS3:PS0 : Timer0 Prescale Selection bits
bit 0:
INTEDG
R/W - 0
TIMER0
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
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
T0CS : Timer0 Clock Source Select bit
This bit selects the clock source for TMR0.
1 = Internal instruction clock cycle (T
0 = T0CKI pin
These bits select the prescale value for TMR0.
Unimplemented : Read as '0'
PS3:PS0
R/W - 0
T0SE
0000
0001
0010
0011
0100
0101
0110
0111
1xxx
R/W - 0
T0CS
Prescale Value
This document was created with FrameMaker 4 0 4
1:128
1:256
1:16
1:32
1:64
R/W - 0
1:1
1:2
1:4
1:8
PS3
(ADDRESS: 05h, UNBANKED)
R/W - 0
PS2
CY
)
R/W - 0
PS1
R/W - 0
PS0
U - 0
—
bit0
R = Readable bit
W = Writable bit
U = Unimplemented,
-n = Value at POR reset
PIC17C4X
Read as '0'
DS30412C-page 67