PIC16LF1526 Datasheet, PDF (169/354 Pages) Microchip Technology – 64-Pin Flash Microcontrollers with nanoWatt XLP Technology

PIC16(L)F1526/27
18.1 Timer1/3/5 Operation
The Timer1/3/5 module is a 16-bit incrementing counter
which is accessed through the TMRxH:TMRxL register
pair. Writes to TMRxH or TMRxL 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.
Timer1/3/5 is enabled by configuring the TMRxON and
TMRxGE bits in the TxCON and TxGCON registers,
respectively. Table 18-1 displays the Timer1/3/5 enable
selections.
TABLE 18-1:
TMRxON
0
0
1
1
TIMER1/3/5 ENABLE
SELECTIONS
TMRxGE
0
1
0
1
Timer1/3/5
Operation
Off
Off
Always On
Count Enabled
18.2 Clock Source Selection
The TMRxCS<1:0> and SOSCEN bits of the TxCON
register are used to select the clock source for
Timer1/3/5. Table 18-2 displays the clock source
selections.
18.2.1 INTERNAL CLOCK SOURCE
When the internal clock source is selected the
TMRxH:TMRxL register pair will increment on multiples
of FOSC as determined by the Timer1/3/5 prescaler.
When the FOSC internal clock source is selected, the
Timer1/3/5 register value will increment by four counts
every instruction clock cycle. Due to this condition, a
2 LSB error in resolution will occur when reading the
Timer1/3/5 value. To utilize the full resolution of
Timer1/3/5, an asynchronous input signal must be used
to gate the Timer1/3/5 clock input.
The following asynchronous sources may be used:
• Asynchronous event on the TxG pin to Timer1/3/5
gate
18.2.2 EXTERNAL CLOCK SOURCE
When the external clock source is selected, the
Timer1/3/5 module may work as a timer or a counter.
When enabled to count, Timer1/3/5 is incremented on
the rising edge of the external clock input TxCKI 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:
•Timer1/3/5 enabled after POR
•Write to TMRxH or TMRxL
•Timer1/3/5 is disabled
•Timer1/3/5 is disabled (TMRxON = 0)
when TxCKI is high then Timer1/3/5
is enabled (TMRxON = 1) when
TxCKI is low.
TABLE 18-2:
TMRxCS1
0
0
1
1
1
CLOCK SOURCE SELECTIONS
TMRxCS0
0
1
0
0
1
SOSCEN
x
x
0
0
x
Clock Source
Instruction Clock (FOSC/4)
System Clock (FOSC)
External Clocking on T1CKI Pin
External Clocking on T1CKI Pin
Capacitive Sensing Oscillator
 2011 Microchip Technology Inc.
Preliminary
DS41458A-page 169