PIC18FXX8 Datasheet, PDF (128/402 Pages) Microchip Technology – 28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

PIC18FXX8
15.3 Compare Mode
In Compare mode, the 16-bit CCPR1 and ECCPR1
register value is constantly compared against either the
TMR1 register pair value or the TMR3 register pair
value. When a match occurs, the CCP1 pin can have
one of the following actions:
• Driven high
• Driven low
• Toggle output (high-to-low or low-to-high)
• Remains unchanged
The action on the pin is based on the value of control
bits CCP1M3:CCP1M0. At the same time, interrupt flag
bit CCP1IF is set.
15.3.1 CCP1 PIN CONFIGURATION
The user must configure the CCP1 pin as an output by
clearing the appropriate TRISC bit.
Note:
Clearing the CCP1CON register will force
the CCP1 compare output latch to the
default low level. This is not the data latch.
15.3.2 TIMER1/TIMER3 MODE SELECTION
Timer1 and/or Timer3 must be running in Timer mode,
or Synchronized Counter mode, if the CCP module is
using the compare feature. In Asynchronous Counter
mode, the compare operation may not work.
15.3.3 SOFTWARE INTERRUPT MODE
When generate software interrupt is chosen, the CCP1
pin is not affected. Only a CCP interrupt is generated (if
enabled).
15.3.4 SPECIAL EVENT TRIGGER
In this mode, an internal hardware trigger is generated,
which may be used to initiate an action.
The special event trigger output of CCP1 resets either
the TMR1 or TMR3 register pair. Additionally, the
ECCP1 special event trigger will start an A/D
conversion if the A/D module is enabled.
Note:
The special event trigger from the ECCP1
module will not set the Timer1 or Timer3
interrupt flag bits.
FIGURE 15-2:
COMPARE MODE OPERATION BLOCK DIAGRAM
Special Event Trigger will:
Reset Timer1 or Timer3 (but not set Timer1 or Timer3 Interrupt Flag bit)
Set bit GO/DONE which starts an A/D conversion (ECCP1 only)
Special Event Trigger
TMR1H TMR1L
TMR3H TMR3L
Set Flag bit CCP1IF
(PIR1<2>)
T3CCP1
T3ECCP1
CCP1
QS
R
Output
Logic
Match
Output Enable
CCP1CON<3:0>
Mode Select
01
Comparator
CCPR1H CCPR1L
Note 1: I/O pins have diode protection to VDD and VSS.
DS41159D-page 126
 2004 Microchip Technology Inc.