PIC16F819 Microchip Technology Inc., PIC16F819 Datasheet - Page 65

• Manufacturer Part Number: PIC16F819
• Description: 18/20-pin Enhanced Flash Microcontrollers With Nanowatt Technology
• Manufacturer: Microchip Technology Inc.

8.0
Timer2 is an 8-bit timer with a prescaler and a
postscaler. It can be used as the PWM time base for the
PWM mode of the CCP1 module. The TMR2 register is
readable and writable and is cleared on any device
Reset.
The input clock (F
1:4
T2CKPS1:T2CKPS0 (T2CON<1:0>).
The Timer2 module has an 8-bit period register, PR2.
Timer2 increments from 00h until it matches PR2 and
then resets to 00h on the next increment cycle. PR2 is
a readable and writable register. The PR2 register is
initialized to FFh upon Reset.
The match output of TMR2 goes through a 4-bit
postscaler (which gives a 1:1 to 1:16 scaling inclusive)
to generate a TMR2 interrupt (latched in flag bit,
TMR2IF (PIR1<1>)).
Timer2 can be shut-off by clearing control bit, TMR2ON
(T2CON<2>), to minimize power consumption.
Register 8-1 shows the Timer2 Control register.
Additional information on timer modules is available in
the “PICmicro
Manual” (DS33023).
 2004 Microchip Technology Inc.
or
TIMER2 MODULE
1:16,
®
Mid-Range MCU Family Reference
OSC
selected
/4) has a prescale option of 1:1,
by
control
bits,
8.1
The prescaler and postscaler counters are cleared
when any of the following occurs:
• A write to the TMR2 register
• A write to the T2CON register
• Any device Reset (Power-on Reset, MCLR, WDT
TMR2 is not cleared when T2CON is written.
8.2
The output of TMR2 (before the postscaler) is fed to the
Synchronous Serial Port module which optionally uses
it to generate a shift clock.
FIGURE 8-1:
Note 1: TMR2 register output can be software
Reset or Brown-out Reset)
Sets Flag
bit TMR2IF
Postscaler
1:1
to
Timer2 Prescaler and Postscaler
Output of TMR2
1:16
4
selected by the SSP module as a baud clock.
TMR2
Output
Reset
PIC16F818/819
EQ
(1)
Comparator
TMR2 reg
TIMER2 BLOCK DIAGRAM
PR2 reg
1:1, 1:4, 1:16
Prescaler
DS39598E-page 63
2
F
OSC
/4