PIC16F870_13 Datasheet, PDF (55/172 Pages) Microchip Technology – 28/40-Pin, 8-Bit CMOS FLASH Microcontrollers

PIC16F870/871
8.0 CAPTURE/COMPARE/PWM
MODULES
Each 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 and interactions of the
CCP module. In the following sections, the operation of
a CCP module is described.
Additional information on CCP modules is available in
the PIC^® Mid-Range MCU Family Reference Manual
(DS33023) and in application note AN594, “Using the
CCP Modules” (DS00594).
TABLE 8-1: CCP MODE - TIMER
RESOURCES REQUIRED
CCP Mode
Timer Resource
Capture
Compare
PWM
Timer1
Timer1
Timer2
8.1 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).
REGISTER 8-1:
CCP1CON REGISTER REGISTER (ADDRESS: 17h/1Dh)
U-0
U-0
R/W-0 R/W-0
R/W-0
R/W-0
—
—
CCP1X CCP1Y CCP1M3 CCP1M2
bit 7
R/W-0
CCP1M1
R/W-0
CCP1M0
bit 0
bit 7-6
bit 5-4
bit 3-0
Unimplemented: Read as '0'
CCP1X:CCP1Y: 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.
CCP1M3:CCP1M0: CCP1 Mode Select bits
0000 = Capture/Compare/PWM disabled (resets CCP1 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, CCP1 pin is
unaffected)
1011 = Compare mode, trigger special event (CCP1IF bit is set, CCP1 pin is unaffected);
CCP1resets TMR1, and starts an A/D conversion (if A/D module is enabled)
11xx = PWM mode
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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DS30569C-page 55