OPTION_REG datasheet(136/222 Pages) MICROCHIP

136 / 222 page

MCP19111

DS22331A-page 136

 2013 Microchip Technology Inc.

24.3

Timer1 Prescaler

Timer1 has four prescaler options allowing 1, 2, 4 or 8

divisions of the clock input. The T1CKPS bits of the

T1CON register control the prescale counter. The

prescale counter is not directly readable or writable;

however, the prescaler counter is cleared upon a write to

TMR1H or TMR1L.

24.4

Timer1 Interrupt

The Timer1 register pair (TMR1H:TMR1L) increments

to FFFFh and rolls over to 0000h. When Timer1 rolls

over, the Timer1 interrupt flag bit of the PIR1 register is

set. To enable the interrupt on rollover, you must set

these bits:

• TMR1ON bit of the T1CON register

• TMR1IE bit of the PIE1 register

• PEIE bit of the INTCON register

• GIE bit of the INTCON register

The interrupt is cleared by clearing the TMR1IF bit in

the Interrupt Service Routine.

24.5

Timer1 in Sleep

Unlike other standard mid-range Timer1 modules, the

MCP19111 Timer1 module only clocks from an internal

system clock, and thus does not run during Sleep

mode, nor can be used to wake the device from this

mode.

24.6

Timer1 Control Register

The Timer1 Control register (T1CON), shown in

various features of the Timer1 module.

Note:

The TMR1H:TMR1L register pair and the

TMR1IF bit should be cleared before

enabling interrupts.

T1CON: TIMER1 CONTROL REGISTER

U-0

R/W-0

U-0

R/W-0/

R/W-0

—

T1CKPS1

T1CKPS0

—

TMR1CS

TMR1ON

bit 7

bit 0

Legend:

R = Readable bit

P = Programmable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-6

Unimplemented: Read as ‘0’

bit 5-4

T1CKPS<1:0>: Timer1 Input Clock Prescale Select bits

= 1:8 Prescale value

= 1:4 Prescale value

= 1:2 Prescale value

= 1:1 Prescale value

bit 3-2

Unimplemented: Read as ‘0’

bit 1

TMR1CS: Timer1 Clock Source Control bit

= 8 MHz system clock (FOSC)

= 2 MHz instruction clock (FOSC)

bit 0

TMR1ON: Timer1 On bit

= Enables Timer1

=Stops Timer1

Clears Timer1 gate flip-flop

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