PIC16C662-20/TQ Microchip Technology, PIC16C662-20/TQ Datasheet - Page 44

• Manufacturer Part Number: PIC16C662-20/TQ
• Description: 8-Bit EPROM Microcontrollers with Analog Comparators
• Manufacturer: Microchip Technology

PIC16C64X & PIC16C66X
6.3
An 8-bit counter is available as a prescaler for the
Timer0 module or as a postscaler for the Watchdog
Timer (WDT), respectively (Figure 6-6). For simplicity,
this counter is being referred to as “prescaler” through-
out this data sheet. Note that the prescaler may be
used by either the Timer0 module or the Watchdog
Timer, but not both. Thus, a prescaler assignment for
the Timer0 module means that there is no prescaler for
the Watchdog Timer, and vice-versa.
FIGURE 6-6:
DS30559A-page 44
RA4/T0CKI
Note: T0CS, T0SE, PSA, PS2:PS0 are (OPTION<5:0>).
CLKOUT (=Fosc/4)
WDT Enable bit
pin
Watchdog
Timer
Prescaler
BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
T0SE
0
1
PSA
M
U
X
0
1
T0CS
M
U
X
0
8-bit Prescaler
8 - to - 1MUX
Time-out
8
M U X
WDT
Preliminary
1
0
1
PSA
M
U
X
The PSA and PS2:PS0 bits (OPTION<3:0>) determine
the prescaler assignment and prescale ratio.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g., CLRF 1, MOVWF 1,
BSF
assigned to Watchdog Timer, a CLRWDT instruction will
clear the prescaler count along with the Watchdog
Timer. The prescaler is not readable or writable.
PSA
PS2:PS0
1,x ) will clear the prescaler count. When
Cycles
SYNC
2
1996 Microchip Technology Inc.
TMR0 reg
Data Bus
8
Set flag bit T0IF
on Overflow