PIC16F722AT-ISS Datasheet, PDF (104/286 Pages) Microchip Technology – 28-Pin Flash Microcontrollers with nanoWatt XLP Technology

PIC16(L)F722A/723A
12.1 Timer1 Operation
The Timer1 module is a 16-bit incrementing counter
which is accessed through the TMR1H:TMR1L register
pair. Writes to TMR1H or TMR1L directly update the
counter.
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 incre-
ments 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. Table 12-1 displays the Timer1 enable
selections.
TABLE 12-1:
TMR1ON
0
0
1
1
TIMER1 ENABLE
SELECTIONS
TMR1GE
Timer1
Operation
0
Off
1
Off
0
Always On
1
Count Enabled
12.2 Clock Source Selection
The TMR1CS<1:0> and T1OSCEN bits of the T1CON
register are used to select the clock source for Timer1.
Table 12-2 displays the clock source selections.
12.2.1 INTERNAL CLOCK SOURCE
When the internal clock source is selected the
TMR1H:TMR1L register pair will increment on multiples
of FISC as determined by the Timer1 prescaler.
12.2.2 EXTERNAL CLOCK SOURCE
When the external clock source is selected, the Timer1
module may work as a timer or a counter.
When enabled to count, Timer1 is increment ed on the
rising edge of the external clock input T1CKI or the
capacitive sensing oscillator signal. Either of these
external clock sources can be synchronized to the
microcontroller system clock or they can run
asynchronously.
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:
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
•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.
TABLE 12-2:
TMR1CS1
0
0
1
1
1
CLOCK SOURCE SELECTIONS
TMR1CS0
T1OSCEN
Clock Source
1
x
System Clock (FOSC)
0
x
Instruction Clock (FOSC/4)
1
x
Capacitive Sensing Oscillator
0
0
External Clocking on T1CKI Pin
0
1
Oscillator Circuit on T1OSI/T1OSO Pins
DS41417B-page 104
 2010-2012 Microchip Technology Inc.