Re: [CAD_CAM_EDM_DRO] Re:Inductosyn DRO was balls

On Thursday 31 October 2002 16:25, JJ wrote:

> You might want to look at the Atmel line of microcontrollers. There are
> several asm, c, and BASIC compilers around, some free. In particular,
> the AT90S8535 has 8 A/D channels, as well as a serial port and other
> nifty I/O. Plus they can be programmed in circuit. The Mega line has
> even more features.
>
> www.atmel.com
>
> Regards,
> JJ
>
> Be Kind, Be Careful, Be Yourself
>
> > -----Original Message-----
> > From: Keith Bowers [mailto:kabowers@...]
> > Sent: Thursday, October 31, 2002 11:21 AM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: Re: [CAD_CAM_EDM_DRO] Re:Inductosyn DRO was balls
> >
> > On Wednesday 30 October 2002 22:53, Bill Higdon wrote:
> > > Keith Bowers wrote:
> > > >>>http://products.analog.com/products/info.asp?product=AD2S90
> > > >>>AD2S90-EB PRODUCTION Evaluation Boards - COMMERCIAL $89.06
> > > >>>AD2S90AP PRODUCTION PLASTIC LEAD CHIP CARRIER 20
> >
> > COMMERCIAL $29.16
> >
> > > >-------
> > > >I expect to need a 2-axis resolver to quadrature board, so
> >
> > I did a bit
> >
> > > > more checking.
> > > >
> > > >The evaluation board price above is quantity 1.
> > > >
> > > >Unfortunately the above price for the chip is quantity 100
> >
> > and is not
> >
> > > >available for online purchase from Analog Devices WEB site.
> > > >
> > > >Pioneer has ad2s90ap in stock with the quantity 1 price as
> >
> > $44.86. You
> >
> > > >probably want an ad2s99 reference oscillator @$10.73 too,
> >
> > but out of
> >
> > > > stock.
> > > >
> > > >At a guess a 2-axis board with just quadrature output
> >
> > could probably be
> >
> > > > hand wired for around $125 with all new parts.
> > > >
> > > >More thinking is in order; such as serial out to a computer.
> > >
> > > I have looked at these, and someone finally got smart! The
> >
> > cost for a
> >
> > > 12 bit board back in 99 was very high. It took 2 8 bit
> >
> > converter chips,
> >
> > > a special chip to add their outputs together, and a high
> >
> > priced osc. The
> >
> > > 8 bit chips were on the order of $300.00 each as I remember, and the
> > > adder was about the same.
> > > Bill Higdon
> >
> > Another thing I have been contemplating is the Maxim
> > MAX157/159 10/20 bit A/Ds
> > along with something like a DS89C420 (33 MHz clock) or maybe
> > the Basic-X
> > stuff to do the arithmetic, but I haven't come up with a
> > simple way to read
> > two signals at the same time since the samples must be
> > perfectly synchronized
> > to the peak of the reference signal. By the time you add a
> > sample and hold
> > chip in front and then read each sample things start to get
> > complicated.
> >
> > A really interesting solution would be the one TI has in a
> > TMS324F240 DSP
> > application note. The approach could be really interesting if it was
> > completed. They don't appear to publish complete code for
> > what they do and do
> > not include quadrature output in the design. The code for one
> > axis, including
> > reference signal generation, used less than 25% of the
> > processor, so it would
> > appear that a 2-axis board might be hand wired for about $50.
> > As usual TI
> > wants a bundle for the associated compiler, but there is a
> > GNU version at the
> > usual price 8o). One would also have to come up with a way
> > to burn the
> > program into a chip. I have never gotten into DSP and would
> > really prefer to
> > make chips with machine tools.
> >
> > The more I write, the better the AD2S90s look <g>.
> > --
> > Keith Bowers - Thomasville, NC
> >
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>

Thanks for the suggestion; It looks interesting. In this case we need to
measure two signals at exactly the same time which will require either two
separate A/Ds per axis or external sample and holds. I was looking at the
Dallas chip both because it appears to be fast and also because back when the
8046/8051 family hit the market I did some design with it. I didn't have
access to an assembler or development system, so had to make my own and hand
assemble the code. I may actually remember something about the code. It's
only been 25 years or so <g>
--
Keith Bowers - Thomasville, NC