Need DDS module, 2nd round

An 8051 compares to ARM like a model T Ford compares to a Volkswagen Golf / Rabbit. IMHO finding a second source for parts is becoming more and more impossible. Just like the XR2206 8051 microcontrollers may become extinct real soon as well.

There are many situations where a Model T gets you there. When I rode in a Model A a while ago I was pleasantly surprised how comfortable that was.

However, if it is possible one should always prefer the part that has

That's been said since over 15 years :-)

Fancy ramped, modulated DDS sinewave generation at 200K samples/sec would be no sweat for a $4 ARM, and you get a mux'd ADC and a DAC for free. But yes, it would take some code slinging.

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And I'll probably do that if this becomes a product, with whatever processor the local SW folks can handle without a major learning curve. Just not right now, got to watch work load, expenses and time line. So it'll be analog for now.

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If you do go ARM, let me know if you'd like some example C code to butcher. We have an app that uses an ADC interrupt to do a filtering + PID algorithm, ADC in to DAC out, on an LPC1754. The algorithm is pretty fancy, and we run it at 100 KHz with the internal uP clock throttled down to 50 MHz. We pay $3.55 each, pre-programmed by a distributor.

Bring your programmer and we'll go to Zeitgeist and we'll explain our code and the DDS theory. Your treat, of course.

Today I'm writing a PowerBasic program to graph a bunch of thermocouple temperature controller params vs time. It's slow, graphing coffee cups of hot water cooling off. Thermal stuff is always tedious.

You can keep a thermocouple to within a tenth degree of 25C by holding the lead in your mouth, roughly 6" from the junction, sliding it a bit left or right to keep the temp on target, varying the thermal conduction. You can even do it hands-off with a bit of practice.

Pro tip: Remove thermocouple element from Inconel 600 thermowell before attempting.

Best regards, Spehro Pefhany

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I wonder what's the temperature of a well-stirred mixture of crushed ice, rum, and Coke. That deserves further research.

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That sounds good. Although this project would fit much nicer into a Cypress PSoC because that has lots of useful analog functions in there. Like S/C filters that can be pressed into service as mixers.

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I'd try to gauge the thermal effects of foam recombination on an Anchor Steam OBA. Problem is, with me it won't stay in the glass for too long.

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I just saw the new STM32F3xx, cortexM4 with all the usual interfaces and up to four opamps/PGAs and seven comparators

-Lasse

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A well-stirred ice bath, made with distilled water and pure ice, sits at 0C (273.15K) to about +/-0.001K, if the US NBS is to be believed. Adding anti-freeze is going to make it cooler and less predictable, and there's a risk that your measurments will become less reliable as the experiment progresses, not that anybody prepared to drink either rum or Coke is to be trusted in the first place.

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Beer foam collapses because the CO2 inside the bubbles diffuses out a lot faster than O2 and N2 diffuse in - the latter two are much less soluble in the water film than the CO2.

The thermodynamics might be interesting, but are probably too dominated by the evaporation of water and ethanol justify any serious measurement effort.

Too bad. Last night when I was reading some of your other posts in this thread I realized you were looking for a module you could put on your board. I have a module that would suit your needs with a little programming of the FPGA. It has a small FPGA, a 24 bit stereo CODEC, op amps and could do just what you seem to need. The programming would not be a big deal. The job it was designed for is similar and mostly I would just need to rearrange the code pieces a bit.

Yeah, I had a very nice one and someone walked off with it. I really should break down and get another. They are worth their price. In the mean time I have gone to using two pair of reading glasses. If I set them on each other just right they give me three different magnifications, tri-focals!

BTW, I dug into my sig gen this morning and I don't like what I found. What I mean by that is I don't understand it. I'll post some details in the thread I started about it a couple of weeks ago.

Maybe next time. Nico had also offered to built one, which was nice.

Their site is currently not working properly but article numbers 17653TL and 17654TL would be the head-worn magnifiers. Not very expensive. I'd tell them not to ship UPS, they crushed the first one by tossing the package over the backyard fence. The next one came via US mail, because I insisted.

Hmm, I only remember George Herold's thread about function generators. What's the subject line of the thread?

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That would be nice. But ST is not on my most favored list, mostly because of their IMHO strongly lacking customer service and screwed up web site.

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With a Type K thermocouple immersed in a similar ice-liquid mixture, I get close to 0°C, but the experiment needs to be repeated with better instrumentation.

Best regards, Spehro Pefhany

And the sun will go nova tomorrow.

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And of course repeated many times to get better statistics.

Cheers

Phil Hobbs

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Try some Ron Zacapa 23, straight of course. It makes cognac obsolete.

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Indeed, I've always hated rum, especially rum and coke then I tried a Ron Zacapa and that is damn nice :)

-Lasse