Datasheet

© 2009 Microchip Technology Inc. DS39775C-page 217
PIC18F87J50 FAMILY
18.0 ENHANCED CAPTURE/
COMPARE/PWM (ECCP)
MODULE
In the PIC18F87J10 family of devices, three of the CCP
modules are implemented as standard CCP modules
with Enhanced PWM capabilities. These include the
provision for 2 or 4 output channels, user-selectable
polarity, dead-band control and automatic shutdown
and restart. The Enhanced features are discussed in
detail in Section 18.4 “Enhanced PWM Mode”.
Capture, Compare and single-output PWM functions of
the ECCP module are the same as described for the
standard CCP module.
The control register for the Enhanced CCP module is
shown in Register 18-1. It differs from the CCP4CON/
CCP5CON registers in that the two Most Significant
bits are implemented to control PWM functionality.
In addition to the expanded range of modes available
through the Enhanced CCPxCON register, the ECCP
modules each have two additional registers associated
with Enhanced PWM operation and auto-shutdown
features. They are:
• ECCPxDEL (ECCPx PWM Delay)
• ECCPxAS (ECCPx Auto-Shutdown Control)
REGISTER 18-1: CCPxCON: ECCPx CONTROL REGISTER (ECCP1/ECCP2/ECCP3)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
PxM1 PxM0 DCxB1 DCxB0 CCPxM3 CCPxM2 CCPxM1 CCPxM0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7-6 PxM1:PxM0: Enhanced PWM Output Configuration bits
If CCPxM3:CCPxM2 =
00, 01, 10:
xx = PxA assigned as Capture/Compare input/output; PxB, PxC, PxD assigned as port pins
If CCPxM3:CCPxM2 =
11:
00 = Single output: PxA modulated; PxB, PxC, PxD 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
bit 5-4
DCxB1:DCxB0: PWM Duty Cycle bit 1 and bit 0
Capture mode:
Unused.
Compare mode:
Unused.
PWM mode:
These bits are the two LSbs of the 10-bit PWM duty cycle. The eight MSbs of the duty cycle are found in CCPRxL.
bit 3-0
CCPxM3:CCPxM0: ECCPx Module Mode Select bits
0000 = Capture/Compare/PWM off (resets ECCPx module)
0001 = Reserved
0010 = Compare mode: toggle output on match
0011 = Capture mode
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: initialize ECCPx pin low; set output on compare match (set CCPxIF)
1001 = Compare mode: initialize ECCPx pin high; clear output on compare match (set CCPxIF)
1010 = Compare mode: generate software interrupt only; ECCPx pin reverts to I/O state
1011 = Compare mode: trigger special event (ECCPx resets TMR1 or TMR3, sets CCPxIF bit, ECCP2
trigger also starts A/D conversion if A/D module is enabled)
(1)
1100 = PWM mode: PxA, PxC active-high; PxB, PxD active-high
1101 = PWM mode: PxA, PxC active-high; PxB, PxD active-low
1110 = PWM mode: PxA, PxC active-low; PxB, PxD active-high
1111 = PWM mode: PxA, PxC active-low; PxB, PxD active-low
Note 1: Implemented only for ECCP1 and ECCP2; same as ‘1010’ for ECCP3.