Datasheet

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
Register 24-1, is used to control Timer1 and select the
various features of the Timer1 module.
Note: The TMR1H:TMR1L register pair and the
TMR1IF bit should be cleared before
enabling interrupts.
REGISTER 24-1: T1CON: TIMER1 CONTROL REGISTER
U-0 U-0 R/W-0 R/W-0 U-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
11 = 1:8 Prescale value
10 = 1:4 Prescale value
01 = 1:2 Prescale value
00 = 1:1 Prescale value
bit 3-2 Unimplemented: Read as ‘0’
bit 1 TMR1CS: Timer1 Clock Source Control bit
1 = 8 MHz system clock (F
OSC
)
0 = 2 MHz instruction clock (F
OSC
)
bit 0 TMR1ON: Timer1 On bit
1 = Enables Timer1
0 =Stops Timer1
Clears Timer1 gate flip-flop