Pardon my comandeering of your thread, but since you mention hardware=20
failures, I had a PIC 16F872 fail on me recently in an odd way ... RB0 fr=
oze=20
at logic "1".  I checked the circuit carefully, but did not find any shor=
ts=20
or other problems.  RB0 thru 4 drove the base of some 2N3906 transistors =
via=20
1k resistors.  So I just replaced the PIC, AND swapped the transistor wit=
h=20
another.   But lo and behold -- after a couple days of use, this new one=20
failed in the exact same way.  The third one never failed, but I have to=20
wonder and possibly assume that there was some flaw during manufacture.

Anyone seen these probs before?

Cheers,
-Neil.


On Thursday 12 June 2003 01:46, Dominic Stratten scribbled:
> I was having a similar problem until I put 35 volts throught the PWM ou=
tput
> by accident - now I'm getting a 0% duty cycle ;-)
>
> Experimenting will resume when I dig through my box of bits and liberat=
e
> another 16f628 from an old project.
>
> Dom
> ----- Original Message -----
> From: "Kyrre Aalerud" <kreature@C2I.NET>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Thursday, June 12, 2003 1:49 AM
> Subject: [PIC]: PWM on 16F62x problem?
>
> > Well...  I ironed out the problem on the last interrupt driven proble=
m.
>
> It
>
> > was a faulty PIC going into latchup over nothing.
> >
> > Anyway.  I have another problem.
> > Because of the annoyance of setting the two LSB in the duty-cycle of =
the
> > 16F62x PWM, and since I only needed 8 bits accuracy, I decided to use=
 the
> > upper byte and simply set the lower to 0,0.  Then quadruple the clock=
 for
> > the pwm and I can write the intended value directly to the byte.  Pro=
blem
>
> is
>
> > 100% duty doesn't seem to exist?  I set PR2 to 63 and CCPR1L to 255 a=
nd
> > still my multimeter only registers 3.05 Volts on the pwm output?  I
> > supply the circuit with about 5 Volts.
> >
> > My understanding is that as long as you overshoot the value of PR2 it
> > doesn't matter if you don't use the lower bits.  You still get 100% d=
uty.
> > Any ideas?
> >
> > Oh, and yes I'm building a cheap speed-controller for my RC-plane :)
> > (People should be wondering about now.)
> >
> >     KreAture
> >
> > --
> > http://www.piclist.com hint: PICList Posts must start with ONE topic:
> > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

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