PIC18F25J11-I/PT MICROCHIP [Microchip Technology], PIC18F25J11-I/PT Datasheet - Page 198

• Manufacturer Part Number: PIC18F25J11-I/PT
• Description: 28/44-Pin, Low-Power, High-Performance Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

When the internal clock source is selected, the
PIC18F46J11 FAMILY
12.2
The Timer1 module is an 8-bit or 16-bit incrementing
counter,
TMR1H:TMR1L register pair.
When used with an internal clock source, the module is
a timer and increments on every instruction cycle.
When used with an external clock source, the module
can be used as either a timer or counter and
increments on every selected edge of the external
source.
Timer1 is enabled by configuring the TMR1ON and
TMR1GE bits in the T1CON and T1GCON registers,
respectively.
When Timer1 is enabled, the RC1/T1OSI/RP12 and
RC0/T1OSO/T1CKI/RP11 pins become inputs. This
means the values of TRISC<1:0> are ignored and the
pins are read as ‘0’.
12.3
The TMR1CS<1:0> and T1OSCEN bits of the T1CON
register are used to select the clock source for Timer1.
Register 12-1 displays the clock source selections.
12.3.1
TMR1H:TMR1L register pair will increment on multiples
of F
TABLE 12-1:
DS39932C-page 198
OSC
TMR1CS1
as determined by the Timer1 prescaler.
Timer1 Operation
Clock Source Selection
0
0
1
1
which
INTERNAL CLOCK SOURCE
TIMER1 CLOCK SOURCE SELECTION
is
TMR1CS0
accessed
1
0
0
0
through
T1OSCEN
x
x
0
1
the
Clock Source (F
Instruction Clock (F
External Clock on T1CKI Pin
Oscillator Circuit on T1OSI/T1OSO Pin
external clock sources can be synchronized to the
asynchronously.
12.3.2
When the external clock source is selected, the Timer1
module may work as a timer or a counter.
When enabled to count, Timer1 is incremented on the
rising edge of the external clock input, T1CKI, or the
capacitive sensing oscillator signal. Either of these
microcontroller
When used as a timer with a clock oscillator, an
external 32.768 kHz crystal can be used in conjunction
with the dedicated internal oscillator circuit.
Note:
EXTERNAL CLOCK SOURCE
In Counter mode, a falling edge must be
registered by the counter prior to the first
incrementing rising edge after any one or
more of the following conditions:
• Timer1 enabled after POR Reset
• Write to TMR1H or TMR1L
• Timer1 is disabled
• Timer1 is disabled (TMR1ON = 0)
when T1CKI is high, then Timer1 is
enabled (TMR1ON = 1) when T1CKI is
low.
OSC
system
OSC
Clock Source
)
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© 2009 Microchip Technology Inc.
clock
or
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can
run