F21 datasheet(188/416 Pages) MICROCHIP

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16.4

Input Capture Mode

Input Capture mode is used to capture a timer value

from an independent timer base upon an event on an

input pin or other internal Trigger source. The input

capture features are useful in applications requiring

frequency (time period) and pulse measurement.

Figure 16-6 depicts a simplified block diagram of the

Input Capture mode.

Input Capture mode uses a dedicated 16/32-bit, synchro-

nous, up counting timer for the capture function. The timer

value is written to the FIFO when a capture event occurs.

The internal value may be read (with a synchronization

delay) using the CCPxTMRH/L registers.

To use Input Capture mode, the CCSEL bit

(CCPxCON1L<4>) must be set. The T32 and

MOD<3:0> bits are used to select the proper Capture

mode, as shown in Table 16-3.

FIGURE 16-6:

INPUT CAPTURE x BLOCK DIAGRAM

TABLE 16-3:

INPUT CAPTURE MODES

MOD<3:0>

(CCPxCON1L<3:0>)

T32

(CCPxCON1L<5>)

Operating Mode

0000

Edge Detect (16-bit capture)

0000

Edge Detect (32-bit capture)

0001

Every Rising (16-bit capture)

0001

Every Rising (32-bit capture)

0010

Every Falling (16-bit capture)

0010

Every Falling (32-bit capture)

0011

Every Rise/Fall (16-bit capture)

0011

Every Rise/Fall (32-bit capture)

0100

Every 4th Rising (16-bit capture)

0100

Every 4th Rising (32-bit capture)

0101

Every 16th Rising (16-bit capture)

0101

Every 16th Rising (32-bit capture)

CCPxBUFx

4-Level FIFO Buffer

MOD<3:0>

Set CCPxIF

OPS<3:0>

Interrupt

Logic

System Bus

Event and

Trigger and

Sync Logic

Clock

Select

ICx Clock

Sources

Trigger and

Sync Sources

ICS<2:0>

CCPxTMRH/L

Increment

Reset

T32

Edge Detect Logic

and

Clock Synchronizer

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