Tim ODriscoll a =E9crit :
>=20
> On Sun, 22 Jun 2003, Gaston Gagnon wrote:
> > Tim,
> > Did my suggestion made it to the list or was it discarded for a l=
ack of
> > good sense ?
> > Gaston
> >
> It did make it, but only after I sent my last email :(  Time to cha=
nge
> ISPs I think...
>=20
> I'll paste in your email here:
> > I have not tried this but what about feeding your signal on one i=
nput of
> > a comparator while the other input is connected to the pwm output=
 trough
> > a low pass filter?
> > The comparator output is then used to make the pwm follow your an=
alog
> > signal.
> > Could the time constant of the filter be made small enough ?
> > Gaston
>=20
> Hmm, I don't quite understand what you mean here.. I *think* you me=
an to
> watch the comparator 'match' flag, then read what the PWM pin was d=
oing at
> the that instance? If so, isn't the PWM output a square wave, so my=
 analog
> input will only match if it hits vss or vdd? Or is that what the lo=
w pass
> filter fixes?

The low pass filter output will average the pwm value. A simple RC
network should do.
The idea is to have the pwm output average to match your analog signa=
l.=20
You watch the comparator output to determine if the pwm value should =
be
increased or decreased.
The pwm value is the digital image of your analog signal.

I hope this is clearer %^}
Gaston
=20
 =20
>=20
> Cheers,
>=20
> Tim
>=20
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