PIC18F2220/2320/4220/4320
16.0
ENHANCED CAPTURE/
COMPARE/PWM (ECCP)
MODULE
The ECCP (Enhanced Capture/ Compare/
PWM) module is only available on
PIC18F4X20 devices.
The ECCP module differs from the CCP with the addi-
tion of an enhanced PWM mode which allows for 2 or
4 output channels, user-selectable polarity, dead band
control and automatic shutdown and restart. These
features are discussed in detail in
The control register for CCP1 is shown in Register 16-1.
It differs from the CCP1CON register of PIC18F2X20
devices in that the two Most Significant bits are
implemented to control enhanced PWM functionality.
Note:
In 40 and 44-pin devices, the CCP1 module is
implemented as a standard CCP module with
enhanced PWM capabilities. Operation of the Capture,
Compare and standard single output PWM modes is
described in
Discussion in that section relating to
PWM frequency and duty cycle also apply to the
enhanced PWM mode.
REGISTER 16-1:
CCP1CON REGISTER FOR ENHANCED CCP OPERATION (PIC18F4X20 ONLY)
R/W-0
P1M1
bit 7
R/W-0
P1M0
R/W-0
DC1B1
R/W-0
DC1B0
R/W-0
CCP1M3
R/W-0
CCP1M2
R/W-0
CCP1M1
R/W-0
CCP1M0
bit 0
bit 7-6
bit 5-4
bit 3-0
P1M1:P1M0:
PWM Output Configuration bits
If CCP1M<3:2> =
00, 01, 10
(Capture, Compare, or disabled):
xx
= P1A assigned as Capture/Compare input; P1B, P1C, P1D assigned as port pins
If CCP1M<3:2> =
11
(PWM modes):
00
= Single output; P1A modulated; P1B, P1C, P1D assigned as port pins
01
= Full-bridge output forward; P1D modulated; P1A active; P1B, P1C inactive
10
= Half-bridge output; P1A, P1B modulated with dead band control; P1C, P1D assigned as port pins
11
= Full-bridge output reverse; P1B modulated; P1C active; P1A, P1D inactive
DC1B1:DC1B0:
PWM Duty Cycle 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:
ECCP1 Mode Select bits
0000
= Capture/Compare/PWM off (resets ECCP module)
0001
= Unused (reserved)
0010
= Compare mode, toggle output on match (ECCP1IF bit is set)
0011
= Unused (reserved)
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 (ECCP1IF bit is set)
1001
= Compare mode, clear output on match (ECCP1IF bit is set)
1010
= Compare mode, generate software interrupt on match (ECCP1IF bit is set, ECCP1 pin
operates as a port pin for input and output)
1011
= Compare mode, trigger special event (ECCP1IF bit is set, ECCP resets TMR1or TMR2
and starts an A/D conversion if the A/D module is enabled)
1100
= PWM mode, P1A, P1C active-high, P1B, P1D active-high
1101
= PWM mode, P1A, P1C active-high, P1B, P1D active-low
1110
= PWM mode, P1A, P1C active-low, P1B, P1D active-high
1111
= PWM mode, P1A, P1C active-low, P1B, P1D active-low
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
2003 Microchip Technology Inc.
DS39599C-page 141
MICROCHIP [ MICROCHIP TECHNOLOGY ]
