PIC24FJ64GA705 Datasheet, PDF (161/412 Pages) –

PIC24FJ256GA705 FAMILY
13.0 TIMER2/3
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 “dsPIC33/PIC24 Family Reference
Manual”, “Timers” (DS39704), which is
available from the Microchip web site
(www.microchip.com). The information
in this data sheet supersedes the
information in the FRM.
The Timer2/3 module is a 32-bit timer, which can also be
configured as independent, 16-bit timers with selectable
operating modes.
As a 32-bit timer, Timer2/3 can 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
• A/D Event Trigger (on Timer2/3 in 32-bit mode
and Timer3 in 16-bit mode)
Individually, all of the 16-bit timers can function as
synchronous timers or counters. They also offer the
features listed above, except for the A/D event trigger.
This trigger is implemented only on Timer2/3 in 32-bit
mode and Timer3 in 16-bit mode. The operating modes
and enabled features are determined by setting the
appropriate bit(s) in the T2CON and T3CON registers.
T2CON is shown in generic form in Register 13-1;
T3CON is shown in Register 13-2.
For 32-bit timer/counter operation, Timer2 is the least
significant word; Timer3 is the most significant word of
the 32-bit timer.
Note:
For 32-bit operation, T3CON control bits
are ignored. Only T2CON control bits are
used for setup and control. Timer2 clock
and gate inputs are utilized for the 32-bit
timer modules, but an interrupt is
generated with the Timer3 interrupt flags.
To configure Timer2/3 for 32-bit operation:
1. Set the T32 bit (T2CON<3> = 1).
2. Select the prescaler ratio for Timer2 using the
TCKPS<1:0> bits.
3. Set the Clock and Gating modes using the TCS
and TGATE bits. If TCS is set to an external
clock, RPINRx (TyCK) must be configured to
an available RPn/RPIn pin. For more informa-
tion, see Section 11.5 “Peripheral Pin Select
(PPS)”.
4. Load the timer period value. PR3 will contain the
most significant word (msw) of the value, while
PR2 contains the least significant word (lsw).
5. If interrupts are required, set the interrupt enable
bit, T3IE. Use the priority bits, T3IP<2:0>, to set
the interrupt priority. Note that while Timer2 con-
trols the timer, the interrupt appears as a Timer3
interrupt.
6. Set the TON bit (= 1).
The timer value, at any point, is stored in the register
pair, TMR<3:2>. TMR3 always contains the most
significant word of the count, while TMR2 contains the
least significant word.
To configure any of the timers for individual 16-bit
operation:
1. Clear the T32 bit (T2CON<3>).
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 11.5 “Peripheral
Pin Select (PPS)” 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 (TxCON<15> = 1) bit.
 2016 Microchip Technology Inc.
DS30010118B-page 161