Information

PIC18F2420/2520/4420/4520
DS80209H-page 4 © 2008 Microchip Technology Inc.
12. Module: ECCP
The PWM pin(s) may change state if a breakpoint
is encountered during emulation and an auto-
shutdown event occurs via FLT0. This affects the
MPLAB
®
ICD 2 debugger and the ICE 2000 and
ICE 4000 emulators.
Work around
During emulation, use the comparator for auto-
shutdown. Applications which can tolerate a
shutdown response time of several TCYs may use
the external interrupt flag, INT0IF, to detect a
shutdown event and disable the PWM by clearing
the ECCPASE bit (ECCP1AS<7>).
Date Codes that pertain to this issue:
All engineering and production devices.
13. Module: ECCP and CCP
When operating either Timer1 or Timer3 as a
counter with a prescale value other than 1:1 and
operating the ECCP in Compare mode with the
Special Event Trigger (CCP1CON bits
CCP1M3:CCP1M0 = 1011), the Special Event
Trigger Reset of the timer occurs as soon as there
is a match between TMRxH:TMRxL and
CCPR1H:CCPR1L.
This differs from the PIC18F452, where the Special
Event Trigger Reset of the timer occurs on the next
prescaler output pulse after the match between
TMRxH:TMRxL and CCPR1H:CCPR1L.
Work around
To achieve the same timer Reset period on the
PIC18F4520 family as the PIC18F452 family for a
given clock source, add 1 to the value in
CCPR1H:CCPR1L. In other words, if
CCPR1H:CCPR1L = x for the PIC18F452, to
achieve the same Reset period on the
PIC18F4520 family, CCPR1H:CCPR1L = x + 1,
where the prescale is 1, 2, 4 or 8 depending on the
T1CKPS1:T1CKPS0 bit values.
Date Codes that pertain to this issue:
All engineering and production devices.
14. Module: ECCP
When a shutdown condition occurs, the output port
is made inactive for the duration of the event. After
the event that caused the shutdown ends, the
ECCP module enables the PWM output right away
instead of waiting until the beginning of the next
PWM cycle.
Work around
Disable the auto-restart feature in software, polling
the Timer2 Interrupt Flag (TMR2IF) and wait until it
is set before clearing the ECCPASE bit.
Date Codes that pertain to this issue:
All engineering and production devices.
15. Module: ECCP
When switching direction in Full-Bridge PWM
mode, the modulated outputs will switch immedi-
ately instead of waiting for the next PWM cycle.
This may generate unexpected short pulses on the
modulated outputs.
Work around
Disable the PWM or set duty cycle to zero prior to
switching directions.
Date Codes that pertain to this issue:
All engineering and production devices.