I would look at using chips with the QEI peripheral in them to handle at le=
ast some of the quadrature encoders. IIRC there are PIC24/33 chips that wil=
l handle either 2 or 4 QEI ports, and the 100 pin versions of these chips h=
ave zillions of ADC lines.

Check the PIC24E/PIC33E series as a starting point - but whichever chips yo=
u look at, check the errata, I know some chip families have errors in the Q=
EI.


>=20
> I've been asked if I can conjure up  a device that will allow 6 increment=
al
> rotary encoders and 10 ADC inputs. I suspect this is for some sort of gam=
ing
> doodad.
>=20
> I'm wondering on what the lists thoughts are on saving 12 port pins with =
the
> following.
>=20
> Attach channel A of all the encoders to a single interrupt on change pin.
> The IOC will look for high to low and then low to high.
>=20
> Attach all the B channels to individual pins on a port.
>=20
> On interrupt the complete port with 6 channel B's will be read in and mas=
ked
> in a sequential series to see which pin changed and the state it changed =
to -
> Xoring with a previous state buffer to get direction and count.
>=20
> Does this seem feasible and have I overlooked any pitfalls, other than
> possibly more than one encoder being twiddled at the same time?
>=20
> I would debounce in hardware with probably a 10K pullup and 10nF capacito=
r
> per input.  Pushbuttons on the encoders are not required, but the pins us=
ed
> by an encoder could be substituted with push buttons,  I was thinking of
> having a Pic pin that could be set high or low to signal whether push but=
tons
> or encoders were attached.
>=20
> It wouldn't surprise me if there wasn't a future requirement for the last
> option to be set via a PC to the Pic.
>=20
> Colin
> --
> cdb,  on 23/12/2013
>=20
>=20
>=20
>=20
>=20
>=20
> --
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> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
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