PIC24FV32KA304-I Datasheet, PDF (151/320 Pages) Microchip Technology – 20/28/44/48-Pin, General Purpose, 16-Bit Flash Microcontrollers with XLP Technology

PIC24FV32KA304 FAMILY
14.0 INPUT CAPTURE WITH
DEDICATED TIMERS
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 34. “Input Capture
with Dedicated Timer” (DS39722).
All devices in the PIC24FV32KA304 family features
3 independent input capture modules. Each of the
modules offers a wide range of configuration and
operating options for capturing external pulse events
and generating interrupts.
Key features of the input capture module include:
• Hardware-configurable for 32-bit operation in all
modes by cascading two adjacent modules
• Synchronous and Trigger modes of output
compare operation, with up to 20 user-selectable
trigger/sync sources available
• A 4-level FIFO buffer for capturing and holding
timer values for several events
• Configurable interrupt generation
• Up to 6 clock sources available for each module,
driving a separate internal 16-bit counter
The module is controlled through two registers: ICxCON1
(Register 14-1) and ICxCON2 (Register 14-2). A general
block diagram of the module is shown in Figure 14-1.
14.1 General Operating Modes
14.1.1
SYNCHRONOUS AND TRIGGER
MODES
By default, the input capture module operates in a
free-running mode. The internal 16-bit counter,
ICxTMR, counts up continuously, wrapping around
from FFFFh to 0000h on each overflow, with its period
synchronized to the selected external clock source.
When a capture event occurs, the current 16-bit value
of the internal counter is written to the FIFO buffer.
In Synchronous mode, the module begins capturing
events on the ICx pin as soon as its selected clock
source is enabled. Whenever an event occurs on the
selected sync source, the internal counter is reset. In
Trigger mode, the module waits for a Sync event from
another internal module to occur before allowing the
internal counter to run.
Standard, free-running operation is selected by setting
the SYNCSEL bits to ‘00000’ and clearing the ICTRIG
bit (ICxCON2<7>). Synchronous and Trigger modes
are selected any time the SYNCSEL bits are set to any
value except ‘00000’. The ICTRIG bit selects either
Synchronous or Trigger mode; setting the bit selects
Trigger mode operation. In both modes, the SYNCSEL
bits determine the sync/trigger source.
When the SYNCSEL bits are set to ‘00000’ and
ICTRIG is set, the module operates in Software Trigger
mode. In this case, capture operations are started by
manually setting the TRIGSTAT bit (ICxCON2<6>).
FIGURE 14-1:
INPUT CAPTURE BLOCK DIAGRAM
ICM<2:0>
ICx Pin
Prescaler
Counter
1:1/4/16
ICTSEL<2:0>
Edge Detect Logic
and
Clock Synchronizer
ICI<1:0>
Event and
Interrupt
Logic
Set ICxIF
Clock
Increment
16
IC Clock
Sources
Select
ICxTMR
4-Level FIFO Buffer
16
Trigger and
Sync Sources
Trigger and
Sync Logic _Reset
SYNCSEL<4:0>
Trigger
ICxBUF
ICOV, ICBNE
16
System Bus
 2011 Microchip Technology Inc.
DS39995B-page 151