Datasheet

PIC18F46J11 FAMILY
DS39932D-page 250  2011 Microchip Technology Inc.
18.2.4 ECCP PRESCALER
There are four prescaler settings in Capture mode; they
are specified as part of the operating mode selected by
the mode select bits (CCPxM<3:0>). Whenever the
ECCP module is turned off, or Capture mode is dis-
abled, the prescaler counter is cleared. This means
that any Reset will clear the prescaler counter.
Switching from one capture prescaler to another may
generate an interrupt. Also, the prescaler counter will
not be cleared; therefore, the first capture may be from
a non-zero prescaler. Example 18-1 provides the
recommended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
EXAMPLE 18-1: CHANGING BETWEEN
CAPTURE PRESCALERS
FIGURE 18-1: CAPTURE MODE OPERATION BLOCK DIAGRAM
CLRF CCP1CON ; Turn CCP module off
MOVLW NEW_CAPT_PS ; Load WREG with the
; new prescaler mode
; value and CCP ON
MOVWF CCP1CON ; Load CCP1CON with
; this value
CCPR1H CCPR1L
TMR1H TMR1L
Set CCP1IF
TMR3
Enable
Q1:Q4
CCP1CON<3:0>
ECCP1 pin
Prescaler
 1, 4, 16
and
Edge Detect
TMR1
Enable
T3CCP1
T3CCP1
TMR3H TMR3L
4
4