PIC16F872_06 Datasheet, PDF (45/168 Pages) Microchip Technology – 28-Pin, 8-Bit CMOS Flash Microcontroller with 10-Bit A/D

PIC16F872
7.0 TIMER2 MODULE
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 CCP module(s). The TMR2 reg-
ister is readable and writable, and is cleared on any
device RESET.
The input clock (FOSC/4) has a prescale option of 1:1,
1:4 or 1:16, selected by control bits
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 7-1 shows the Timer2 Control register.
Additional information on timer modules is available in
the PICmicro™ Mid-Range MCU Family Reference
Manual (DS33023).
FIGURE 7-1:
TIMER2 BLOCK DIAGRAM
Sets Flag
bit TMR2IF
TOMuRtp2ut₍₁₎
Reset
TMR2 reg
Postscaler
Comparator
1:1 to 1:16 _EQ
4
T2OUTPS3:
T2OUTPS0
PR2 reg
Prescaler
1:1, 1:4, 1:16 ^FOSC/4
2
T2CKPS1:
T2CKPS0
Note 1: TMR2 register output can be software selected by the
SSP module as a baud clock.
REGISTER 7-1:
T2CON: TIMER2 CONTROL REGISTER (ADDRESS 12h)
U-0
—
bit 7
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0
bit 0
bit 7
bit 6-3
bit 2
bit 1-0
Unimplemented: Read as '0'
TOUTPS3:TOUTPS0: Timer2 Output Postscale Select bits
0000 = 1:1 Postscale
0001 = 1:2 Postscale
0010 = 1:3 Postscale
•
•
•
1111 = 1:16 Postscale
TMR2ON: Timer2 On bit
1 = Timer2 is on
0 = Timer2 is off
T2CKPS1:T2CKPS0: Timer2 Clock Prescale Select bits
00 = Prescaler is 1
01 = Prescaler is 4
1x = Prescaler is 16
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
’1’ = Bit is set
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared x = Bit is unknown
© 2006 Microchip Technology Inc.
DS30221C-page 43