PIC24FJ256GB108-I Datasheet, PDF (163/352 Pages) Microchip Technology – 64/80/100-Pin, 16-Bit Flash Microcontrollers with USB On-The-Go (OTG)

PIC24FJ256GB110 FAMILY
12.0 TIMER2/3 AND TIMER4/5
Note:
This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information, refer to the
“PIC24F Family Reference Manual”,
Section 14. “Timers” (DS39704).
The Timer2/3 and Timer4/5 modules are 32-bit timers,
which can also be configured as four independent, 16-bit
timers with selectable operating modes.
As 32-bit timers, Timer2/3 and Timer4/5 can each
operate in three modes:
• Two independent 16-bit timers with all 16-bit
operating modes (except Asynchronous Counter
mode)
• Single 32-bit timer
• Single 32-bit synchronous counter
They also support these features:
• Timer Gate Operation
• Selectable Prescaler Settings
• Timer Operation during Idle and Sleep modes
• Interrupt on a 32-Bit Period Register Match
• ADC Event Trigger (Timer4/5 only)
Individually, all four of the 16-bit timers can function as
synchronous timers or counters. They also offer the
features listed above, except for the ADC Event
Trigger; this is implemented only with Timer3. The
operating modes and enabled features are determined
by setting the appropriate bit(s) in the T2CON, T3CON,
T4CON and T5CON registers. T2CON and T4CON are
shown in generic form in Register 12-1; T3CON and
T5CON are shown in Register 12-2.
For 32-bit timer/counter operation, Timer2 and Timer4
are the least significant word; Timer3 and Timer4 are
the most significant word of the 32-bit timers.
Note:
For 32-bit operation, T3CON and T5CON
control bits are ignored. Only T2CON and
T4CON control bits are used for setup and
control. Timer2 and Timer4 clock and gate
inputs are utilized for the 32-bit timer
modules, but an interrupt is generated with
the Timer3 or Timer5 interrupt flags.
To configure Timer2/3 or Timer4/5 for 32-bit operation:
1. Set the T32 bit (T2CON<3> or T4CON<3> = 1).
2. Select the prescaler ratio for Timer2 or Timer4
using the TCKPS<1:0> bits.
3. Set the Clock and Gating modes using the TCS
and TGATE bits. If TCS is set to external clock,
RPINRx (TxCK) must be configured to an avail-
able RPn pin. See Section 10.4 “Peripheral
Pin Select” for more information.
4. Load the timer period value. PR3 (or PR5) will
contain the most significant word of the value
while PR2 (or PR4) contains the least significant
word.
5. If interrupts are required, set the interrupt enable
bit, T3IE or T5IE; use the priority bits, T3IP<2:0>
or T5IP<2:0>, to set the interrupt priority. Note
that while Timer2 or Timer4 controls the timer,
the interrupt appears as a Timer3 or Timer5
interrupt.
6. Set the TON bit (= 1).
The timer value, at any point, is stored in the register
pair, TMR3:TMR2 (or TMR5:TMR4). TMR3 (TMR5)
always contains the most significant word of the count,
while TMR2 (TMR4) contains the least significant word.
To configure any of the timers for individual 16-bit
operation:
1. Clear the T32 bit corresponding to that timer
(T2CON<3> for Timer2 and Timer3 or
T4CON<3> for Timer4 and Timer5).
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. See Section 10.4 “Peripheral
Pin Select” for more information.
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 (TxCON<15> = 1).
 2009 Microchip Technology Inc.
DS39897C-page 163