Datasheet
1999-2013 Microchip Technology Inc. Preliminary DS41124D-page 49
PIC16C745/765
8.0 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 (F
INT/4) has a prescale option of 1:1,
1:4 or 1:16, selected by control bits T2CKPS<1:0>
(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 PIC Mid-Range MCU Family Reference Manual
(DS33023).
8.1 Timer2 Prescaler and Postscaler
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 (POR, MCLR
Reset, WDT
Reset or BOR)
TMR2 is not cleared when T2CON is written.
FIGURE 8-1: TIMER2 BLOCK DIAGRAM
REGISTER 8-1: TIMER2 CONTROL REGISTER (T2CON: 12h)
Comparator
TMR2
Sets flag
TMR2 reg
output
RESET
Postscaler
Prescaler
PR2 reg
2
FINT
1:1 1:16
1:1, 1:4, 1:16
EQ
4
bit TMR2IF
to
T2OUTPS<3:0>
T2CKPS<1:0>
U-0 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 R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
- n = Value at POR reset
bit7 bit0
bit 7: Unimplemented: Read as '0'
bit 6-3: TOUTPS<3:0>: Timer2 Output Postscale Select bits
0000 = 1:1 Postscale
0001 = 1:2 Postscale
0010 = 1:3 Postscale
•
•
•
1111 = 1:16 Postscale
bit 2: TMR2ON: Timer2 On bit
1 = Timer2 is on
0 = Timer2 is off
bit 1-0: T2CKPS<1:0>: Timer2 Clock Prescale Select bits
00 = Prescaler is 1
01 = Prescaler is 4
1x = Prescaler is 16