
2010-2012 Microchip Technology Inc.
DS39977F-page 279
PIC18F66K80 FAMILY
A shutdown condition is indicated by the ECCP1ASE
(Auto-Shutdown Event Status) bit (ECCP1AS<7>). If
the bit is a ‘0’, the PWM pins are operating normally. If
the bit is a ‘1’, the PWM outputs are in the shutdown
state.
When a shutdown event occurs, two things happen:
The ECCP1ASE bit is set to ‘1’. The ECCP1ASE
will remain set until cleared in firmware or an
The enabled PWM pins are asynchronously
placed in their shutdown states. The PWM output
pins are grouped into pairs (P1A/P1C) and
(P1B/P1D). The state of each pin pair is
determined by the PSS1ACx and PSS1BDx bits
(ECCP1AS<3:2> and <1:0>, respectively).
Each pin pair may be placed into one of three states:
Drive logic ‘1’
Drive logic ‘0’
Tri-state (high-impedance)
REGISTER 20-3:
ECCP1AS: ECCP1 AUTO-SHUTDOWN CONTROL REGISTER
R/W-0
ECCP1ASE
ECCP1AS2
ECCP1AS1
ECCP1AS0
PSS1AC1
PSS1AC0
PSS1BD1
PSS1BD0
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
ECCP1ASE:
ECCP Auto-Shutdown Event Status bit
1
= A shutdown event has occurred; ECCP outputs are in a shutdown state
0
= ECCP outputs are operating
bit 6-4
ECCP1AS<2:0>:
ECCP Auto-Shutdown Source Select bits
000
= Auto-shutdown is disabled
001
= Comparator C1OUT output is high
010
= Comparator C2OUT output is high
011
= Either Comparator C1OUT or C2OUT is high
100
=VIL on FLT0 pin
101
=VIL on FLT0 pin or Comparator C1OUT output is high
110
=VIL on FLT0 pin or Comparator C2OUT output is high
111
=VIL on FLT0 pin or Comparator C1OUT or Comparator C2OUT is high
bit 3-2
PSS1AC<1:0>:
P1A and P1C Pins Shutdown State Control bits
00
= Drive pins, P1A and P1C, to ‘0’
01
= Drive pins, P1A and P1C, to ‘1’
1x
= Pins, P1A and P1C, tri-state
bit 1-0
PSS1BD<1:0>:
P1B and P1D Pins Shutdown State Control bits
00
= Drive pins, P1B and P1D, to ‘0’
01
= Drive pins, P1B and P1D, to ‘1’
1x
= Pins, P1B and P1D, tri-state
Note 1:
The auto-shutdown condition is a level-based signal, not an edge-based signal. As long as the level is
present, the auto-shutdown will persist.
2:
Writing to the ECCP1ASE bit is disabled while an auto-shutdown condition persists.
3:
Once the auto-shutdown condition has been removed and the PWM restarted (either through firmware or
auto-restart), the PWM signal will always restart at the beginning of the next PWM period.