Datasheet

© 2007-2011 Microchip Technology Inc. DS70265E-page 149
dsPIC33FJ12MC201/202
13.0 INPUT CAPTURE
The Input Capture module is useful in applications
requiring frequency (period) and pulse measurement.
The dsPIC33FJ12MC201/202 devices support up to
eight input capture channels.
The Input Capture module captures the 16-bit value of
the selected Time Base register when an event occurs
at the ICx pin. The events that cause a capture event
are listed below in three categories:
1. Simple Capture Event modes:
- Capture timer value on every falling edge of
input at ICx pin
- Capture timer value on every rising edge of
input at ICx pin
2. Capture timer value on every edge (rising and
falling)
3. Prescaler Capture Event modes:
- Capture timer value on every 4th rising edge
of input at ICx pin
- Capture timer value on every 16th rising
edge of input at ICx pin
Each Input Capture channel can select one of two
16-bit timers (Timer2 or Timer3) for the time base.
The selected timer can use either an internal or
external clock.
Other operational features include:
• Device wake-up from capture pin during CPU
Sleep and Idle modes
• Interrupt on Input Capture event
• 4-word FIFO buffer for capture values
- Interrupt optionally generated after 1, 2, 3, or
4 buffer locations are filled
• Use of Input Capture to provide additional
sources of external interrupts
FIGURE 13-1: INPUT CAPTURE BLOCK DIAGRAM
Note 1: This data sheet summarizes the features
of the dsPIC33FJ12MC201/202 family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to Section 12. “Input Cap-
ture” (DS70198) of the “dsPIC33F/
PIC24H Family Reference Manual”,
which is available from the Microchip
website (www.microchip.com).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
ICxBUF
ICx Pin
ICM<2:0> (ICxCON<2:0>)
Mode Select
3
10
Set Flag ICxIF
(in IFSn Register)
TMR2 TMR3
Edge Detection Logic
16
16
FIFO
R/W
Logic
ICxI<1:0>
ICOV, ICBNE (ICxCON<4:3>)
ICxCON
Interrupt
Logic
System Bus
From 16-bit Timers
ICTMR
(ICxCON<7>)
FIFO
Prescaler
Counter
(1, 4, 16)
and
Clock Synchronizer
Note: An ‘x’ in a signal, register or bit name denotes the number of the capture channel.