PIC18F45J10 FAMILY
14.3.2
TIMER1 MODE SELECTION
14.3 Compare Mode
Timer1 must be running in Timer mode or Synchro-
nized Counter mode if the CCP module is using the
compare feature. In Asynchronous Counter mode, the
compare operation may not work.
In Compare mode, the 16-bit CCPRx register value is
constantly compared against the TMR1 register value.
When a match occurs, the CCPx pin can be:
• driven high
• driven low
14.3.3
SOFTWARE INTERRUPT MODE
• toggled (high-to-low or low-to-high)
When the Generate Software Interrupt mode is chosen
(CCPxM<3:0> = 1010), the corresponding CCPx pin is
not affected. Only a CCP interrupt is generated, if
enabled and the CCPxIE bit is set.
• remain unchanged (that is, reflects the state of the
I/O latch)
The action on the pin is based on the value of the mode
select bits (CCPxM<3:0>). At the same time, the inter-
rupt flag bit, CCPxIF, is set.
14.3.4
SPECIAL EVENT TRIGGER
Both CCP modules are equipped with a Special Event
Trigger. This is an internal hardware signal generated
in Compare mode to trigger actions by other modules.
The Special Event Trigger is enabled by selecting
the Compare Special Event Trigger mode
(CCPxM<3:0> = 1011).
14.3.1
CCP PIN CONFIGURATION
The user must configure the CCPx pin as an output by
clearing the appropriate TRIS bit.
Note:
Clearing the CCP2CON register will force
the RB3 or RC1 compare output latch
(depending on device configuration) to the
default low level. This is not the PORTB or
PORTC I/O data latch.
For either CCP module, the Special Event Trigger resets
the Timer register pair for whichever timer resource is
currently assigned as the module’s time base. This
allows the CCPRx registers to serve as a Programmable
Period register for either timer.
The Special Event Trigger for CCP2 can also start an
A/D conversion. In order to do this, the A/D converter
must already be enabled.
FIGURE 14-2:
COMPARE MODE OPERATION BLOCK DIAGRAM
Special Event Trigger
(Timer1 Reset)
Set CCP1IF
CCPR1H
CCPR1L
CCP1 pin
S
R
Q
Output
Logic
Compare
Match
Comparator
TRIS
Output Enable
4
CCP1CON<3:0>
TMR1H
TMR1L
Special Event Trigger
(Timer1 Reset, A/D Trigger)
Set CCP2IF
CCP2 pin
S
Q
Compare
Match
Output
Logic
Comparator
R
TRIS
Output Enable
4
CCPR2H
CCPR2L
CCP2CON<3:0>
DS39682E-page 130
© 2009 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
