Datasheet

 2010 Microchip Technology Inc. DS41302D-page 101
PIC12F609/615/617/12HV609/615
11.4.4 ENHANCED PWM AUTO-
SHUTDOWN MODE
The PWM mode supports an Auto-Shutdown mode that
will disable the PWM outputs when an external
shutdown event occurs. Auto-Shutdown mode places
the PWM output pins into a predetermined state. This
mode is used to help prevent the PWM from damaging
the application.
The auto-shutdown sources are selected using the
ECCPASx bits of the ECCPAS register. A shutdown
event may be generated by:
•A logic ‘0’ on the INT pin
•Comparator
• Setting the ECCPASE bit in firmware
A shutdown condition is indicated by the ECCPASE
(Auto-Shutdown Event Status) bit of the ECCPAS
register. 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. Refer to Figure 1.
When a shutdown event occurs, two things happen:
The ECCPASE bit is set to ‘1’. The ECCPASE will
remain set until cleared in firmware or an auto-restart
occurs (see Section 11.4.5 “Auto-Restart Mode”).
The enabled PWM pins are asynchronously placed in
their shutdown states. The state of P1A is determined by
the PSSAC bit. The state of P1B is determined by the
PSSBD bit. The PSSAC and PSSBD bits are located in
the ECCPAS register. Each pin may be placed into one
of three states:
• Drive logic ‘1’
• Drive logic ‘0’
• Tri-state (high-impedance)
FIGURE 11-10: AUTO-SHUTDOWN BLOCK DIAGRAM
PSSAC<1>
TRISx
P1A
0
1
P1A_DRV
PSSAC<0>
PSSBD<1>
TRISx
P1B
0
1
PSSBD<0>
P1B_DRV
000
001
010
011
100
101
110
111
From Comparator
ECCPAS<2:0>
R
DQ
S
ECCPASE
From Data Bus
Write to ECCPASE
PRSEN
INT