Microchip Technology MA330024 Data Sheet

DS70000591F-page 220

 2009-2014 Microchip Technology Inc.

The Timer2/3/4/5 modules can operate in one of the
following modes:

• Timer  mode

• Gated Timer mode

• Synchronous Counter mode

In Timer and Gated Timer modes, the input clock is
derived from the internal instruction cycle clock (F

CY

).

In Synchronous Counter mode, the input clock is
derived from the external clock input at the TxCK pin.

The timer modes are determined by the following bits:

• TCS (TxCON<1>): Timer Clock Source Control bit

• TGATE (TxCON<6>): Timer Gate Control bit

Timer control bit settings for different operating modes
are given in the 

To configure any of the timers for individual 16-bit
operation:

1.

Clear the T32 bit corresponding to that timer.

2.

Select the timer prescaler ratio using the
TCKPS<1:0> bits.

3.

Set the Clock and Gating modes using the TCS
and TGATE bits.

4.

Load the timer period value into the PRx
register.

5.

If interrupts are required, set the interrupt enable
bit, TxIE. Use the priority bits, TxIP<2:0>, to set
the interrupt priority.

6.

Set the TON bit.

A 32-bit timer module can be formed by combining a
Type B and a Type C 16-bit timer module. For 32-bit
timer operation, the T32 control bit in the Type B Timer
Control (TxCON<3>) register must be set. The Type C
timer holds the most significant word (msw) and the
Type B timer holds the least significant word (lsw)
for 32-bit operation. 

When configured for 32-bit operation, only the Type B
Timerx Control (TxCON) register bits are required for
setup and control while the Type C Timer Control
register bits are ignored (except the TSIDL bit).

For interrupt control, the combined 32-bit timer uses
the interrupt enable, interrupt flag and interrupt priority
control bits of the Type C timer. The interrupt control
and status bits for the Type B timer are ignored
during 32-bit timer operation.

The timers that can be combined to form a 32-bit timer
are listed in 

A block diagram representation of the 32-bit timer
module is shown in 

. The 32-timer module

can operate in one of the following modes:

• Timer mode

• Gated Timer mode

• Synchronous Counter mode

To configure the timer features for 32-bit operation:

1.

Set the T32 control bit.

2.

Select the prescaler ratio for Timer2 using the
TCKPS<1:0> bits.

3.

Set the Clock and Gating modes using the
corresponding TCS and TGATE bits.

4.

Load the timer period value. PR3 contains the
most significant word of the value, while PR2
contains the least significant word.

5.

If interrupts are required, set the interrupt enable
bit, T3IE. Use the priority bits, T3IP<2:0>, to set
the interrupt priority. While Timer2 controls the
timer, the interrupt appears as a Timer3
interrupt.

6.

Set the corresponding TON bit.

Timer 

0

0

Gated Timer

0

1

Synchronous Counter

1

x

Timer2

Timer3

TImer4

Timer5