PIC18F47J53 Datasheet, PDF (273/586 Pages) Microchip Technology – 28/44-Pin, High-Performance USB Microcontrollers with nanoWatt XLP Technology

PIC18F47J53 FAMILY
19.2.2 TIMER1/TIMER3 MODE SELECTION
The timers that are to be used with the capture feature
(Timer1 and/or Timer3) must be running in Timer mode
or Synchronized Counter mode. In Asynchronous
Counter mode, the capture operation may not work.
The timer to be used with each ECCP module is
selected in the CCPTMRS0 register (Register 19-2).
19.2.3 SOFTWARE INTERRUPT
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep the
CCPxIE interrupt enable bit clear to avoid false interrupts.
The interrupt flag bit, CCPxIF, should also be cleared
following any such change in operating mode.
19.2.4 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 19-1 provides the
recommended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
EXAMPLE 19-1: CHANGING BETWEEN
CAPTURE PRESCALERS
CLRF
MOVLW
MOVWF
ECCP1CON ; Turn ECCP module off
NEW_CAPT_PS ; Load WREG with the
; new prescaler mode
; value and ECCP ON
CCP1CON
; Load ECCP1CON with
; this value
FIGURE 19-1:
CAPTURE MODE OPERATION BLOCK DIAGRAM
ECCP1 Pin
Set CCP1IF
C1TSEL0
C1TSEL1
C1TSEL2
Prescaler
 1, 4, 16
and
Edge Detect
C1TSEL0
C1TSEL1
C1TSEL2
CCP1CON<3:0> ⁴
Q1:Q4 ⁴
TMR3H
TMR3L
TMR3
Enable
CCPR1H CCPR1L
TMR1
Enable
TMR1H TMR1L
 2010 Microchip Technology Inc.
Preliminary
DS39964B-page 273