PIC14000-04 Microchip Technology, PIC14000-04 Datasheet - Page 37

• Manufacturer Part Number: PIC14000-04
• Description: 28-Pin Programmable Mixed Signal Controller
• Manufacturer: Microchip Technology

6.0
The PIC14000 contains two general purpose timer
modules, Timer0 (TMR0) and the Watchdog Timer
(WDT). The ADTMR is described in the A/D section.
The Timer0 module is identical to the Timer0 module of
the PIC16C7X enhanced core products. It is an 8-bit
overflow counter.
The Timer0 module has a programmable prescaler
option. This prescaler can be assigned to either the
Timer0 module or the Watchdog Timer (WDT). PSA
(OPTION<3>) assigns the prescaler, and PS2:PS0
(OPTION<2:0>) determines the prescaler value.
Timer0 can increment at the following rates: 1:1 (when
prescaler assigned to Watchdog Timer), 1:2, 1:4, 1:8,
1:16, 1:32, 1:64, 1:128, 1:256.
The Timer0 module has the following features:
FIGURE 6-1:
1996 Microchip Technology Inc.
RC3/T0CKI
pin
HIBERNATE
TIMER MODULES
Oscillator
18 mS
Enable
Timer
Local
T0SE
TIMER0 AND WATCHDOG TIMER BLOCK DIAGRAM
F
WDT
Enable Bit
OSC
/4
This document was created with FrameMaker 4 0 4
Watchdog Timer
T0CS
0
1
PSA
0
1
Note: T0CS, T0SE, PSA, PS2:PS0 correspond to (OPTION<5:0>).
Preliminary
8-bit Counter
Timer0
8-to-1 MUX
1
8
0
Time-out
• 8-bit timer
• Readable and writable (file address 01h)
• 8-bit software programmable prescaler
• Interrupt on overflow from FFh to 00h
Figure 6-1 is a simplified block diagram of the Timer0
module.
The Timer0 module will increment every instruction
cycle (without prescaler). If TMR0 is written, increment
is inhibited for the following two cycles (Figure 6-2 and
Figure 6-3). The user can compensate by writing an
adjusted value to TMR0.
PSA
WDT
1
0
PSout
(2 cycle delay)
PSA
Sync with
3
Internal
Postscaler
Prescaler/
clocks
PS2:PS0
PSout
PIC14000
Data bus
TMR0
Set T0IF
Interrupt on
Overflow
DS40122B-page 37
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