PIC16F872 Datasheet, PDF (47/160 Pages) Microchip Technology – 28-Pin, 8-Bit CMOS FLASH Microcontroller

PIC16F872
8.0 CAPTURE/COMPARE/PWM
MODULE
The Capture/Compare/PWM (CCP) module contains a
16-bit register which can operate as a:
• 16-bit Capture register
• 16-bit Compare register
• PWM master/slave Duty Cycle register
Table 8-1 shows the resources used by the CCP mod-
ule. In the following sections, the operation of a CCP
module is described.
CCP1 Module:
Capture/Compare/PWM Register1 (CCPR1) is com-
prised of two 8-bit registers: CCPR1L (low byte) and
CCPR1H (high byte). The CCP1CON register controls
the operation of CCP1. The special event trigger is
generated by a compare match and will reset Timer1
and start an A/D conversion (if the A/D module is
enabled).
Additional information on CCP modules is available in
the PICmicro™ Mid-Range MCU Family Reference
Manual (DS33023) and in Application Note 594, “Using
the CCP Modules” (DS00594).
TABLE 8-1: CCP MODE - TIMER
RESOURCES REQUIRED
CCP Mode
Timer Resource
Capture
Compare
PWM
Timer1
Timer1
Timer2
REGISTER 8-1: CCP1CON REGISTER (ADDRESS: 17h)
U-0
—
bit7
U-0 R/W-0 R/W-0
R/W-0
— CCP1X CCP1Y CCP1M3
bit 7-6: Unimplemented: Read as ’0’
R/W-0
CCP1M2
R/W-0
CCP1M1
R/W-0
CCP1M0
bit0
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as
‘0’
- n = Value at POR reset
bit 5-4: CCP1<X:Y>: PWM Least Significant bits
Capture Mode: Unused
Compare Mode: Unused
PWM Mode: These bits are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPR1L.
bit 3-0: CCP1M<3:0>: CCPx Mode Select bits
0000 = Capture/Compare/PWM off (resets CCP module)
0100 = Capture mode, every falling edge
0101 = Capture mode, every rising edge
0110 = Capture mode, every 4th rising edge
0111 = Capture mode, every 16th rising edge
1000 = Compare mode, set output on match (CCP1IF bit is set)
1001 = Compare mode, clear output on match (CCP1IF bit is set)
1010 = Compare mode, generate software interrupt on match (CCP1IF bit is set, CCP pin is unaffected)
1011 = Compare mode, trigger special event (CCP1IF bit is set, CCP1 pin is unaffected); CCP1 resets
TMR1 and starts an A/D conversion (if A/D module is enabled)
11xx = PWM mode
© 1999 Microchip Technology Inc.
Preliminary
DS30221A-page 47