PIC32MX440F256H-80I Datasheet, PDF (364/646 Pages) Microchip Technology – 64/100-Pin General Purpose and USB 32-Bit Flash Microcontrollers

PIC32MX3XX/4XX
15.1 Timer Selection
The input capture module can select between one of
two 16-bit timers for the time base, or two 16-bit timers
together to form a 32-bit timer. Setting ICTMR
(ICxCON<7>) to ‘0’ selects the Timer3 for capture.
Setting ICTMR (ICxCON<7>) to 1 selects the Timer2
for capture.
An input capture channel configured to support 32-bit
capture, may use a 32-bit timer resource for capture.
By setting ICC32 (ICxCON<8>) to ‘1’, a 32-bit timer
resource is captured. The 32-bit timer resource is
routed into the module using the existing 16-bit timer
inputs.
The timers clock can be setup using the internal periph-
eral clock source, or using a synchronized external
clock source applied at the TxCK pin.
15.2 Simple Capture Event Modes
These modes are specified by setting the ICM
(ICxCON<2:0>) bits to ‘010’, ‘011’, or ‘110’. Setting
ICM = ‘011’ configures the module to capture the timer
value on any rising edge of the capture input. ICM =
‘010’ configures the module to capture the timer on any
falling edge of the capture input. Setting ICM = ‘110’
configures the channel to capture the timer on every
transition of the capture input, beginning with the edge
specified by ICFEDGE (ICxCON<9>). In Simple Cap-
ture Event mode, the prescaler is not used. See
Figure 15-2 for simplified timing diagrams of a simple
capture event.
Note:
Since the capture input must be synchro-
nized to the peripheral clock, the module
captures the timer count value, which is valid
2-3 peripheral clock cycles (TPB) after the
capture event.
An input capture interrupt event is generated after one,
two, three or four timer count captures, as configured
by ICI (ICxCON<6:5>).
FIGURE 15-2:
SIMPLE CAPTURE EVENT TIMING DIAGRAM CAPTURE EVERY RISING EDGE
Peripheral Clock
Timer Count
n
n+1
n+2
m
m+1 m+2 m+3 m+4 m+5
ICx Input
Synchronized Capture
Capture Data
Capture Interrupt
n+2
m+3
15.3 Prescaled Capture Event Modes
In Prescaled Capture Event mode, the input capture
module triggers a capture event on either every fourth
or every sixteenth rising edge. These modes are
selected by setting the ICM (ICxCON<2:0>) bits to
‘100’ or ‘101’, respectively.
Note: Since the capture input must be synchro-
nized to the peripheral clock, the timer count
value is captured, which is valid 2-3
peripheral clock periods after the capture
event.
DS61143E-page 362
Preliminary
© 2008 Microchip Technology Inc.