PIC18F2480 MICROCHIP [Microchip Technology], PIC18F2480 Datasheet - Page 186

• Manufacturer Part Number: PIC18F2480
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2480/2580/4480/4580
16.4.7.1
The auto-shutdown feature can be configured to allow
automatic restarts of the module following a shutdown
event. This is enabled by setting the PRSEN bit of the
ECCP1DEL register (ECCP1DEL<7>).
In Shutdown mode with PRSEN = 1 (Figure 16-10), the
ECCPASE bit will remain set for as long as the cause
of the shutdown continues. When the shutdown condi-
tion clears, the ECCP1ASE bit is cleared. If PRSEN = 0
(Figure 16-11), once a shutdown condition occurs, the
ECCPASE bit will remain set until it is cleared by
firmware. Once ECCPASE is cleared, the Enhanced
PWM will resume at the beginning of the next PWM
period.
Independent of the PRSEN bit setting, if the
auto-shutdown source is one of the comparators, the
shutdown condition is a level. The ECCPASE bit
cannot be cleared as long as the cause of the shutdown
persists.
The Auto-Shutdown mode can be forced by writing a ‘1’
to the ECCPASE bit.
FIGURE 16-10:
FIGURE 16-11:
DS39637A-page 184
Note:
Shutdown
Shutdown
ECCPASE bit
PWM
ECCPASE bit
PWM
Writing to the ECCPASE bit is disabled
while a shutdown condition is active.
Auto-Shutdown and Auto-Restart
Activity
Activity
Event
Event
PWM Period
PWM Period
PWM AUTO-SHUTDOWN (PRSEN = 1, AUTO-RESTART ENABLED)
PWM AUTO-SHUTDOWN (PRSEN = 0, AUTO-RESTART DISABLED)
Start of
Start of
Normal PWM
Normal PWM
Preliminary
Event Occurs
Event Occurs
PWM Period
PWM Period
Shutdown
Shutdown
signal levels, or activates the PWM output(s).
16.4.8
When the ECCP module is used in the PWM mode, the
application hardware must use the proper external pull-up
and/or pull-down resistors on the PWM output pins. When
the microcontroller is released from Reset, all of the I/O
pins are in the high-impedance state. The external circuits
must keep the power switch devices in the off state until
the microcontroller drives the I/O pins with the proper
The CCP1M1:CCP1M0 bits (ECCP1CON<1:0>) allow
the user to choose whether the PWM output signals are
active-high or active-low for each pair of PWM output
pins (P1A/P1C and P1B/P1D). The PWM output
polarities must be selected before the PWM pins are
configured as outputs. Changing the polarity configura-
tion while the PWM pins are configured as outputs is
not recommended, since it may result in damage to the
application circuits.
The P1A, P1B, P1C and P1D output latches may not be
in the proper states when the PWM module is initialized.
Enabling the PWM pins for output at the same time as
the ECCP module may cause damage to the applica-
tion circuit. The ECCP module must be enabled in the
proper output mode and complete a full PWM cycle
before configuring the PWM pins as outputs. The com-
pletion of a full PWM cycle is indicated by the TMR2IF
bit being set as the second PWM period begins.
Event Clears
Event Clears
Shutdown
Shutdown
START-UP CONSIDERATIONS
ECCPASE
Cleared by
Firmware
 2004 Microchip Technology Inc.
Resumes
Resumes
PWM
PWM