I have just created a simple application using the 8Mhz internal oscillator
of a PIC18F2520.  The problem is that about half the time the oscillator
doesn't start on power up.  I am required to use an existing analog 12V
power supply ahead of a 78L05 regulator.  I have discovered that the
oscillator will start every time if I connect the 12V to the board after th=
e
power supply has already stabilized, so I inferred that it was the slow ris=
e
rate of the analog supply that was causing the problem.  However, it looks
like I am getting 0 to 5V at the PIC Vdd pin in about 20 ms, which seems to
be well within the minimum rise rate spec of 0.05 V/ms.  I have tried
various combinations of Configuration bits, i.e., Power-Up-Timer enabled /
disabled, Brown-Out-Detect enabled / disabled, etc. but that doesn't seem t=
o
make any difference.  The hardware is extremely simple, so I must be missin=
g
something in the firmware.  Any suggestions for where I might look would be
much appreciated.  Thanks,  Foster

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.