William "Chops" Westfield wrote:
>=20
> On Nov 16, 2012, at 12:00 AM, David Meiklejohn wrote:
>=20
> > For half-bridge motor control, I'm thinking that the L293 is the way
> to go.
>   :
> > As for full-bridge, I'm leaning toward using discrete MOSFETs,
>=20
> I don't get it.  "for the more complex example, I'm leaning toward more
> complex circuitry"??  Why not use the L293 for both half-bridge and
> full-bridge examples?

Yes, I see what you're saying.  The problem I've had is that I can't find
(and I've been looking...) a motor driver that interfaces to the PIC, using
the 4 x PWM outputs (P1A - P1D on a 16F684) configured in full-bridge mode.
I also can't see how to configure a L293 (or anything similar) in a way tha=
t
would demonstrate the PIC's full-bridge PWM mode.  If you can point out any
examples, I'll happily adopt them!

Remember, I'm not trying to show how to make an H-bridge to drive a motor.
The key is to have something that is driven from those 4 full-bridge PWM
outputs, demonstrating forward and reverse operation as defined in the PIC
data sheet.  An H-bridge driven by a single-output PWM and a GPIO that
controls forward/reverse is elegant, but doesn't serve to illustrate the PW=
M
modes as described in the PIC data sheet.

> I don't think a half-bridge is useful for driving a motor.=20

Quite possibly - and if that's the case, I'll write that in the tutorial.
I'm already illustrating half-bridge with a piezo (push-pull giving twice
the effective voltage).  I've seen power supply examples, and driving an
audio transformer.  Any other ideas?


Thanks,
David



--=20
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