PIC16F1946 Datasheet, PDF (212/440 Pages) Microchip Technology – 64-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt XLP Technology

PIC16F/LF1946/47
22.2 Compare Mode
The Compare mode function described in this section
is available and identical for CCP modules ECCP1,
ECCP2, ECCP3, CCP4 and CCP5.
Compare mode makes use of the 16-bit Timer1
resource. The 16-bit value of the CCPRxH:CCPRxL
register pair is constantly compared against the 16-bit
value of the TMR1H:TMR1L register pair. When a
match occurs, one of the following events can occur:
• Toggle the CCPx output
• Set the CCPx output
• Clear the CCPx output
• Generate a Special Event Trigger
• Generate a Software Interrupt
The action on the pin is based on the value of the
CCPxM<3:0> control bits of the CCPxCON register. At
the same time, the interrupt flag CCPxIF bit is set.
All Compare modes can generate an interrupt.
Figure 22-2 shows a simplified diagram of the
Compare operation.
FIGURE 22-2:
COMPARE MODE
OPERATION BLOCK
DIAGRAM
CCPxM<3:0>
Mode Select
CCPx
Pin
Set CCPxIF Interrupt Flag
4 ^(PIRx)
CCPRxH CCPRxL
Q S _Output
R ^Logic
Match
Comparator
TRIS
Output Enable
TMR1H TMR1L
Special Event Trigger
Special Event Trigger will:
• CCP<4:1>: Reset Timer1, but not set interrupt flag bit
TMR1IF.
• CCP5: Reset Timer1, but not set interrupt flag bit and set bit
GO/DONE (ADCON0<1>).
22.2.1 CCP PIN CONFIGURATION
The user must configure the CCPx pin as an output by
clearing the associated TRIS bit.
Also, the CCPx pin function can be moved to
alternative pins using the APFCON register. Refer to
Section 12.1 “Alternate Pin Function” for more
details.
Note:
Clearing the CCPxCON register will force
the CCPx compare output latch to the
default low level. This is not the PORT I/O
data latch.
22.2.2 TIMER1 MODE RESOURCE
In Compare mode, Timer1 must be running in either
Timer mode or Synchronized Counter mode. The
compare operation may not work in Asynchronous
Counter mode.
See Section 20.0 “Timer1 Module with Gate Control”
for more information on configuring Timer1.
Note:
Clocking Timer1 from the system clock
(FOSC) should not be used in Capture
mode. In order for Capture mode to
recognize the trigger event on the CCPx
pin, TImer1 must be clocked from the
instruction clock (FOSC/4) or from an
external clock source.
22.2.3 SOFTWARE INTERRUPT MODE
When Generate Software Interrupt mode is chosen
(CCPxM<3:0> = 1010), the CCPx module does not
assert control of the CCPx pin (see the CCPxCON
register).
22.2.4 SPECIAL EVENT TRIGGER
When Special Event Trigger mode is chosen
(CCPxM<3:0> = 1011), the CCPx module does the
following:
• Resets Timer1
• Starts an ADC conversion if ADC is enabled
(CCP5 only)
The CCPx module does not assert control of the CCPx
pin in this mode.
The Special Event Trigger output of the CCP occurs
immediately upon a match between the TMR1H,
TMR1L register pair and the CCPRxH, CCPRxL
register pair. The TMR1H, TMR1L register pair is not
reset until the next rising edge of the Timer1 clock. The
Special Event Trigger output starts an A/D conversion
(if the A/D module is enabled). This feature is only
available on CCP5. This allows the CCPRxH, CCPRxL
register pair to effectively provide a 16-bit
programmable period register for Timer1.
Note 1: The Special Event Trigger from the CCP
module does not set interrupt flag bit
TMR1IF of the PIR1 register.
2: Removing the match condition by
changing the contents of the CCPRxH
and CCPRxL register pair, between the
clock edge that generates the Special
Event Trigger and the clock edge that
generates the Timer1 Reset, will preclude
the Reset from occurring.
DS41414A-page 210
Preliminary
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