PIC18F2525_08 Datasheet, PDF (150/412 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F2525/2620/4525/4620
In addition to the expanded range of modes available
through the CCP1CON and ECCP1AS registers, the
ECCP module has an additional register associated
with Enhanced PWM operation and auto-shutdown
features; it is:
• PWM1CON (PWM Configuration)
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.
To configure the I/O pins as PWM outputs, the proper
PWM mode must be selected by setting the
P1M1:P1M0 and CCP1M3:CCP1M0 bits. The
appropriate TRISC and TRISD direction bits for the port
pins must also be set as outputs.
16.1.1 ECCP MODULES AND TIMER
RESOURCES
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”.
16.2 Capture and Compare Modes
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.
16.2.1 SPECIAL EVENT TRIGGER
The Special Event Trigger output of ECCP1 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.
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.
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 Operation”. The latter is more
generic and will work for either single or
multi-output PWM.
TABLE 16-1: PIN ASSIGNMENTS FOR VARIOUS ECCP1 MODES
ECCP Mode
CCP1CON
Configuration
RC2
RD5
RD6
RD7
All 40/44-pin devices:
Compatible CCP
00xx 11xx
CCP1
RD5/PSP5
RD6/PSP6
RD7/PSP7
Dual PWM
10xx 11xx
P1A
P1B
RD6/PSP6
RD7/PSP7
Quad PWM
x1xx 11xx
P1A
P1B
P1C
P1D
Legend: x = Don’t care. Shaded cells indicate pin assignments not used by ECCP1 in a given mode.
DS39626E-page 148
© 2008 Microchip Technology Inc.