PIC16C72-04SLASHSS datasheet(65/288 Pages) MICROCHIP

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DS30390E-page 65

PIC16C7X

8.0

TIMER1 MODULE

The Timer1 module is a 16-bit timer/counter consisting

of two 8-bit registers (TMR1H and TMR1L) which are

readable and writable. The TMR1 Register pair

(TMR1H:TMR1L) increments from 0000h to FFFFh

and rolls over to 0000h. The TMR1 Interrupt, if enabled,

is generated on overﬂow which is latched in interrupt

ﬂag bit TMR1IF (PIR1<0>). This interrupt can be

enabled/disabled by setting/clearing TMR1 interrupt

enable bit TMR1IE (PIE1<0>).

Timer1 can operate in one of two modes:

• As a timer

• As a counter

The operating mode is determined by the clock select

bit, TMR1CS (T1CON<1>).

Applicable Devices

72 73 73A 74 74A 76 77

In timer mode, Timer1 increments every instruction

cycle.

In counter mode, it increments on every rising

edge of the external clock input.

Timer1 can be enabled/disabled by setting/clearing

control bit TMR1ON (T1CON<0>).

Timer1 also has an internal “reset input”. This reset can

be generated by either of the two CCP modules

(Section 10.0). Figure 8-1 shows the Timer1 control

For the PIC16C72/73A/74A/76/77, when the Timer1

oscillator is enabled (T1OSCEN is set), the RC1/

T1OSI/CCP2 and RC0/T1OSO/T1CKI pins become

inputs. That is, the TRISC<1:0> value is ignored.

For the PIC16C73/74, when the Timer1 oscillator is

enabled (T1OSCEN is set), RC1/T1OSI/CCP2 pin

becomes an input, however the RC0/T1OSO/T1CKI

pin will have to be conﬁgured as an input by setting the

TRISC<0> bit.

FIGURE 8-1:

T1CON: TIMER1 CONTROL REGISTER (ADDRESS 10h)

U-0

R/W-0

—

T1CKPS1 T1CKPS0 T1OSCEN

T1SYNC

TMR1CS TMR1ON

= Readable bit

W = Writable bit

= Unimplemented bit,

read as ‘0’

- n = Value at POR reset

bit7

bit0

bit 7-6:

Unimplemented: Read as '0'

bit 5-4: T1CKPS1:T1CKPS0: Timer1 Input Clock Prescale Select bits

= 1:8 Prescale value

= 1:4 Prescale value

= 1:2 Prescale value

= 1:1 Prescale value

bit 3:

T1OSCEN: Timer1 Oscillator Enable Control bit

1 = Oscillator is enabled

0 = Oscillator is shut off

Note: The oscillator inverter and feedback resistor are turned off to eliminate power drain

bit 2:

T1SYNC: Timer1 External Clock Input Synchronization Control bit

TMR1CS = 1

1 = Do not synchronize external clock input

0 = Synchronize external clock input

TMR1CS = 0

This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.

bit 1:

TMR1CS: Timer1 Clock Source Select bit

1 = External clock from pin RC0/T1OSO/T1CKI (on the rising edge)

0 = Internal clock (FOSC/4)

bit 0:

TMR1ON: Timer1 On bit

1 = Enables Timer1

0 = Stops Timer1

PIC16C72-04/SS Datasheet(PDF) 65 Page - Microchip Technology

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