Datasheet

PIC16C7X
DS30390E-page 72  1997 Microchip Technology Inc.
FIGURE 10-1: CCP1CON REGISTER (ADDRESS 17h)/CCP2CON REGISTER (ADDRESS 1Dh)
U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
— — CCPxX CCPxY CCPxM3 CCPxM2 CCPxM1 CCPxM0 R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
- n =Value at POR reset
bit7 bit0
bit 7-6: Unimplemented: Read as '0'
bit 5-4: CCPxX:CCPxY: 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 CCPRxL.
bit 3-0: CCPxM3:CCPxM0: CCPx Mode Select bits
0000 = Capture/Compare/PWM off (resets CCPx 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 (CCPxIF bit is set)
1001 = Compare mode, clear output on match (CCPxIF bit is set)
1010 = Compare mode, generate software interrupt on match (CCPxIF bit is set, CCPx pin is unaffected)
1011 = Compare mode, trigger special event (CCPxIF bit is set; CCP1 resets TMR1; CCP2 resets TMR1
and starts an A/D conversion (if A/D module is enabled))
11xx = PWM mode
10.1 Capture Mode
In Capture mode, CCPR1H:CCPR1L captures the
16-bit value of the TMR1 register when an event occurs
on pin RC2/CCP1. An event is defined as:
• Every falling edge
• Every rising edge
• Every 4th rising edge
• Every 16th rising edge
An event is selected by control bits CCP1M3:CCP1M0
(CCP1CON<3:0>). When a capture is made, the inter-
rupt request flag bit CCP1IF (PIR1<2>) is set. It must
be cleared in software. If another capture occurs before
the value in register CCPR1 is read, the old captured
value will be lost.
10.1.1 CCP PIN CONFIGURATION
In Capture mode, the RC2/CCP1 pin should be config-
ured as an input by setting the TRISC<2> bit.
Applicable Devices
72
73 73A 74 74A 76 77
Note: If the RC2/CCP1 is configured as an out-
put, a write to the port can cause a capture
condition.
FIGURE 10-2: CAPTURE MODE
OPERATION BLOCK
DIAGRAM
10.1.2 TIMER1 MODE SELECTION
Timer1 must be running in timer mode or synchronized
counter mode for the CCP module to use the capture
feature. In asynchronous counter mode, the capture
operation may not work.
10.1.3 SOFTWARE INTERRUPT
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep bit
CCP1IE (PIE1<2>) clear to avoid false interrupts and
should clear the flag bit CCP1IF following any such
change in operating mode.
CCPR1H CCPR1L
TMR1H TMR1L
Set flag bit CCP1IF
(PIR1<2>)
Capture
Enable
Q’s
CCP1CON<3:0>
RC2/CCP1
Prescaler
÷ 1, 4, 16
and
edge detect
Pin