Dear all,
Still in my experiment.
My application use AT89S52.



my program listing:

LJMP 00A0H
ORG 000BH
LJMP T0SERV

INIT:
ORG 00A0H
SETB EA
MOV TMOD,#01H
SETB ET0
MAIN:
SETB TR0
SETB P1.0 ;RELAY ENERGIZE
LJMP MAIN

T0SERV:
CPL P1.6 ;LED PULSE
CPL P1.7 ;TEST POINT PULSE
RETI

My project sometimes not work properly (hang), after I disturbing my system with pushing push button on off repeately.
If it is happen, the condition is like stopped X-tal oscilator LED not blink and signal at the test point not given.
and this is lIke the power down mode.
My question,
is possible the SFR (PCON) value changed it self? althought my program not access the PCON.
How to recover the cpu clock after hang? (software mode)

thank you verymuch.


regard

hendryawan