PIC16LC773 datasheet(45/200 Pages) MICROCHIP

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PIC16C77X

Advance Information

DS30275A-page 45

6.0

TIMER2 MODULE

The Timer2 module timer has the following features:

• 8-bit timer (TMR2 register)

• 8-bit period register (PR2)

• Readable and writable (Both registers)

• Software programmable prescaler (1:1, 1:4, 1:16)

• Software programmable postscaler (1:1 to 1:16)

• Interrupt on TMR2 match of PR2

• SSP module optional use of TMR2 output to gen-

erate clock shift

Timer2 has a control register, shown in Figure 6-1.

Timer2 can be shut off by clearing control bit TMR2ON

(T2CON<2>) to minimize power consumption.

Figure 6-2 is a simplified block diagram of the Timer2

module.

Additional information on timer modules is available in

the

PICmicro™

Mid-Range

Reference

Manual,

(DS33023).

6.1

Timer2 Operation

Timer2 can be used as the PWM time-base for PWM

mode of the CCP module.

The TMR2 register 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

1:16,

selected

control

bits

T2CKPS1:T2CKPS0 (T2CON<1:0>).

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>)).

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 reset,

Watchdog Timer reset, or Brown-out Reset)

TMR2 is not cleared when T2CON is written.

FIGURE 6-1:

T2CON: TIMER2 CONTROL REGISTER (ADDRESS 12h)

U-0

R/W-0

—

TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0

TMR2ON

T2CKPS1 T2CKPS0

= Readable bit

W = Writable bit

= Unimplemented bit,

read as ‘0’

- n = Value at POR reset

bit7

bit0

bit 7:

Unimplemented: Read as '0'

bit 6-3:

TOUTPS3:TOUTPS0: Timer2 Output Postscale Select bits

0000

= 1:1 Postscale

0001

= 1:2 Postscale

•

1111

= 1:16 Postscale

bit 2:

TMR2ON: Timer2 On bit

1 = Timer2 is on

0 = Timer2 is off

bit 1-0:

T2CKPS1:T2CKPS0: Timer2 Clock Prescale Select bits

= Prescaler is 1

= Prescaler is 4

= Prescaler is 16

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