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Subject:	Re: [geda-user] Design suggestions...
From:	Peter Clifton <pcjc2 AT cam DOT ac DOT uk>
To:	geda-user AT delorie DOT com
Date:	Thu, 22 Dec 2011 00:52:34 +0000
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On Wed, 2011-12-21 at 15:15 -0500, DJ Delorie wrote:
> On some the chips I use, "four channels" means you can choose four
> different duty cycles but only one master frequency.  That would be
> sufficient for your purposes.

Yes, they often have a several "compare" outputs / drive pins for a
single ramp-generator, so you can accurately program the dead-time of
the half-bridge legs.

Many of these are aimed at 3-phase motor driving, but you can usually
adapt to drive a single H-Bridge.

The AT90PWM3b is the chip I always tend to come back to when looking for
PWM control with simple software. This chip has a lot of PWM hardware,
and, importantly, has a PLL which allows you to run the ramp-generators
quite fast.

http://www.atmel.com/dyn/products/product_card.asp?part_id=3D4239

I always favoured ATMEL due to their gcc toolchain and decent (community
driven) Linux support. I've never used their (Windows) IDE, but
apparently its got bad with recent revisions, and put some people off.

In the mean time, I've used Microchip PICs at work a bit, and have
started to quite like them. Their new IDE, MPLAB-X is actually
cross-platform, and works really well on Linux. I'm not sure how well
their compiler and toolchain works in isolation though (if you prefer
Makefiles to IDEs).


Peter

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