鈥?/div>
ADC event trigger
Timer gate operation
Selectable prescaler settings
Timer operation during Idle and Sleep modes
Interrupt on a 32-bit period register match
16-bit Timer Mode:
In the 16-bit mode, Timer2 and
Timer3 can be configured as two independent 16-bit
timers. Each timer can be set up in either 16-bit Timer
mode or 16-bit Synchronous Counter mode. See
Section 9.0, Timer1 Module for details on these two
Operating modes.
The only functional difference between Timer2 and
Timer3 is that Timer2 provides synchronization of the
clock prescaler output. This is useful for high frequency
external clock inputs.
32-bit Timer Mode:
In the 32-bit Timer mode, the timer
increments on every instruction cycle, up to a match
value preloaded into the combined 32-bit Period
register PR3/PR2, then resets to 鈥?鈥?and continues to
count.
For synchronous 32-bit reads of the Timer2/Timer3
pair, reading the LS Word (TMR2 register) will cause
the MS word to be read and latched into a 16-bit
holding register, termed TMR3HLD.
For synchronous 32-bit writes, the holding register
(TMR3HLD) must first be written to. When followed by
a write to the TMR2 register, the contents of TMR3HLD
will be transferred and latched into the MSB of the
32-bit timer (TMR3).
32-bit Synchronous Counter Mode:
In the 32-bit
Synchronous Counter mode, the timer increments on
the rising edge of the applied external clock signal
which is synchronized with the internal phase clocks.
The timer counts up to a match value preloaded in the
combined 32-bit period register PR3/PR2, then resets
to 鈥?鈥?and continues.
When the timer is configured for the Synchronous
Counter mode of operation and the CPU goes into the
Idle mode, the timer will stop incrementing unless the
TSIDL (T2CON<13>) bit =
0.
If TSIDL =
1,
the timer
module logic will resume the incrementing sequence
upon termination of the CPU Idle mode.
These Operating modes are determined by setting the
appropriate bit(s) in the 16-bit T2CON and T3CON
SFRs.
For 32-bit timer/counter operation, Timer2 is the LS
Word and Timer3 is the MS Word of the 32-bit timer.
Note:
For 32-bit timer 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 module but an interrupt is gen-
erated with the Timer3 interrupt flag (T3IF)
and the interrupt is enabled with the
Timer3 interrupt enable bit (T3IE).
铮?/div>
2004 Microchip Technology Inc.
Preliminary
DS70117C-page 71
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