PIC16F1946 datasheet(212/478 Pages) MICROCHIP

212 / 478 page

PIC16(L)F1946/47

DS41414D-page 212

 2010-2012 Microchip Technology Inc.

22.1

Timer2/4/6 Operation

The clock input to the Timer2/4/6 modules is the

system instruction clock (FOSC/4).

TMRx increments from 00h on each clock edge.

A 4-bit counter/prescaler on the clock input allows direct

input, divide-by-4 and divide-by-16 prescale options.

These options are selected by the prescaler control bits,

TxCKPS<1:0> of the TxCON register. The value of

TMRx is compared to that of the Period register, PRx, on

each clock cycle. When the two values match, the

comparator generates a match signal as the timer

output. This signal also resets the value of TMRx to 00h

the

cycle

and

drives

the

output

counter/postscaler (see Section 22.2 “Timer2/4/6

Interrupt”).

The TMRx and PRx registers are both directly readable

and writable. The TMRx register is cleared on any

device Reset, whereas the PRx register initializes to

FFh. Both the prescaler and postscaler counters are

cleared on the following events:

• a write to the TMRx register

• a write to the TxCON register

• Power-on Reset (POR)

• Brown-out Reset (BOR)

•MCLR Reset

• Watchdog Timer (WDT) Reset

• Stack Overflow Reset

• Stack Underflow Reset

• RESET Instruction

22.2

Timer2/4/6 Interrupt

Timer2/4/6 can also generate an optional device

interrupt. The Timer2/4/6 output signal (TMRx-to-PRx

match)

provides

the

input

for

the

4-bit

counter/postscaler. This counter generates the TMRx

match interrupt flag which is latched in TMRxIF of the

PIRx register. The interrupt is enabled by setting the

TMRx Match Interrupt Enable bit, TMRxIE of the PIEx

A range of 16 postscale options (from 1:1 through 1:16

inclusive) can be selected with the postscaler control

bits, TxOUTPS<3:0>, of the TxCON register.

22.3

Timer2/4/6 Output

The unscaled output of TMRx is available primarily to

the CCP modules, where it is used as a time base for

operations in PWM mode.

Timer2 can be optionally used as the shift clock source

for the MSSPx modules operating in SPI mode.

Additional information is provided in Section 24.0

“Master Synchronous Serial Port (MSSP1 and

MSSP2) Module”

22.4

Timer2/4/6 Operation During Sleep

The Timer2/4/6 timers cannot be operated while the

processor is in Sleep mode. The contents of the TMRx

and PRx registers will remain unchanged while the

processor is in Sleep mode.

Note:

TMRx is not cleared when TxCON is

written.

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