Datasheet

 2010-2013 Microchip Technology Inc. DS40001452D-page 149
PIC16(L)F1516/7/8/9
17.0 TIMER0 MODULE
The Timer0 module is an 8-bit timer/counter with the
following features:
• 8-bit timer/counter register (TMR0)
• 8-bit prescaler (independent of Watchdog Timer)
• Programmable internal or external clock source
• Programmable external clock edge selection
• Interrupt on overflow
• TMR0 can be used to gate Timer1
Figure 17-1 is a block diagram of the Timer0 module.
17.1 Timer0 Operation
The Timer0 module can be used as either an 8-bit timer
or an 8-bit counter.
17.1.1 8-BIT TIMER MODE
The Timer0 module will increment every instruction
cycle, if used without a prescaler. 8-Bit Timer mode is
selected by clearing the TMR0CS bit of the
OPTION_REG register.
When TMR0 is written, the increment is inhibited for
two instruction cycles immediately following the write.
17.1.2 8-BIT COUNTER MODE
In 8-Bit Counter mode, the Timer0 module will increment
on every rising or falling edge of the T0CKI pin.
8-Bit Counter mode, using the T0CKI pin, is selected by
setting the TMR0CS bit in the OPTION_REG register to
‘1’.
The rising or falling transition of the incrementing edge
for either input source is determined by the TMR0SE bit
in the OPTION_REG register.
FIGURE 17-1: BLOCK DIAGRAM OF THE TIMER0
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
TMR0SE
TMR0
PS<2:0>
Data Bus
Set Flag bit TMR0IF
on Overflow
TMR0CS
0
1
0
1
8
8
8-bit
Prescaler
FOSC/4
PSA
Sync
2 T
CY
Overflow to Timer1