PIC18F2420/2520/4420/4520
In addition to the expanded range of modes available
16.2 Capture and Compare Modes
through the CCP1CON register and ECCP1AS
register, the ECCP module has an additional register
associated with Enhanced PWM operation and
auto-shutdown features. It is:
Except for the operation of the Special Event Trigger
discussed below, the Capture and Compare modes of
the ECCP module are identical in operation to that of
CCP2. These are discussed in detail in Section 15.2
“Capture Mode” and Section 15.3 “Compare
Mode”. No changes are required when moving
between 28-pin and 40/44-pin devices.
• PWM1CON (PWM Dead-Band Delay)
16.1 ECCP Outputs and Configuration
The Enhanced CCP module may have up to four PWM
outputs, depending on the selected operating mode.
These outputs, designated P1A through P1D, are
multiplexed with I/O pins on PORTC and PORTD. The
outputs that are active depend on the CCP operating
mode selected. The pin assignments are summarized
in Table 16-1.
16.2.1
SPECIAL EVENT TRIGGER
The Special Event Trigger output of ECCP resets the
TMR1 or TMR3 register pair, depending on which timer
resource is currently selected. This allows the CCPR1
register to effectively be a 16-Bit Programmable Period
register for Timer1 or Timer3.
To configure the I/O pins as PWM outputs, the proper
PWM mode must be selected by setting the P1M<1:0>
and CCP1M<3:0> bits. The appropriate TRISC and
TRISD direction bits for the port pins must also be set
as outputs.
16.3 Standard PWM Mode
When configured in Single Output mode, the ECCP
module functions identically to the standard CCP
module in PWM mode, as described in Section 15.4
“PWM Mode”. This is also sometimes referred to as
“Compatible CCP” mode, as in Table 16-1.
16.1.1
ECCP MODULES AND TIMER
RESOURCES
Note:
When setting up single output PWM
operations, users are free to use either of
the processes described in Section 15.4.4
“Setup for PWM Operation” or
Section 16.4.9 “Setup for PWM Opera-
tion”. The latter is more generic and will
work for either single or multi-output PWM.
Like the standard CCP modules, the ECCP module can
utilize Timers 1, 2 or 3, depending on the mode
selected. Timer1 and Timer3 are available for modules
in Capture or Compare modes, while Timer2 is avail-
able for modules in PWM mode. Interactions between
the standard and Enhanced CCP modules are identical
to those described for standard CCP modules.
Additional details on timer resources are provided in
Section 15.1.1
“CCP
Modules
and
Timer
Resources”.
TABLE 16-1: PIN ASSIGNMENTS FOR VARIOUS ECCP MODES
CCP1CON
ECCP Mode
RC2
RD5
RD6
RD7
Configuration
All 40/44-Pin Devices:
Compatible CCP
Dual PWM
00xx 11xx
10xx 11xx
x1xx 11xx
CCP1
P1A
RD5/PSP5
P1B
RD6/PSP6
RD6/PSP6
P1C
RD7/PSP7
RD7/PSP7
P1D
Quad PWM
P1A
P1B
Legend: x= Don’t care. Shaded cells indicate pin assignments not used by ECCP in a given mode.
DS39631E-page 148
© 2008 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
