Little PICs with hi-res A-D ?

In excruciating detail. We are talking about professional CD/record production here. Sounds like the youngster made the same assumptions as you.

Graham

Eeyore wrote in news: snipped-for-privacy@hotmail.com:

Not as fast as a transient capable of an audible click. Not even if he accelerated a lever that then impacted it up the scale. There's a window of timing range there that you can use. Good to hear an analog answer works though. People didn't work for years at brilliant answers so we can forget them the moment digital models can be made. Some things just aren't that easily modelled, and it interests me that when I asked the same question you did (about PIC's with high bit depth conversion), for different purposes, I also got several suggestions that don't really hit the spot. A year later, this is still true, yet FORTY years ago, my problem was solved by Bob Moog and others with a couple of op-amps and a pair of matched transistors. Which is how I'll do it too, if I ever get back to that project...

Eeyore wrote in news: snipped-for-privacy@hotmail.com:

The step size on encoders is 1. What you do to it after you collect it is your business. If you multiply it by 2, then its 2. If you divide it by

100, its 0.01. My point is that for an input device in a digital system, resolution doesn't have to be a factor.

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Scott
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Scott Seidman wrote in news:Xns9B39ADC8A8E4Ascottseidmanmindspri@130.133.1.4:

For example, I'm not sure any of my scopes have any mechanical pots on them anymore.

All kinds of scopes are going digital:

donald

Mixing engineers don't want controls that need turning 3000 degrees. 300 is what they want.

Graham

Quite possibly but you don't mix on them do you ?

Graham

Scott Seidman wrote in news:Xns9B39ADC8A8E4Ascottseidmanmindspri@130.133.1.4:

Physical step angle does though.

Eeyore wrote in news: snipped-for-privacy@hotmail.com:

I think you'd be quite suprised about how easy the transition between pot and frob knob is. You can make a frob knob's sensitivity speed sensitive if you program it that way. You can store a whole bunch of presets, which you couldn't dream of with pots. You can get them with 2^10 counts per revolution, which is 10 full bits, and you never need to worry about noise, or anything like it, or kid yourself into thinking that you have

12 useful bits because you have a 12 bit ADC.

61R.pdf (1 "cycle" is 4 counts)

It might seem expensive, but you might not need as many of them as you would with pots.

A bit more research is showing me 2048 counts!

_MOTN/2_116_18.pdf

Free up your design a bit. Just because an analog mixing board has a pots controlling amps, that doesn't mean that you need a pot on your input. You could even get a little imaginative with the mechanics. A mechanical mouse uses low res encoders, but they're effectively geared to give killer resolution.

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Scott
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That's not the way mixing engineers work. They need an absolute position to correspond to an absolute volume/gain.

Graham

could you interpolate in software ? response will lag behind manipulation but if done right not by much.

Bye. Jasen

"Eeyore" a écrit dans le message de news: snipped-for-privacy@hotmail.com...

Why not a PSoC from Cypress ? You can implement a 14 bit ADC in its analog configurable blocs, and there are 8-pin devices in the family.

Yours,

--
Robert Lacoste
ALCIOM - The mixed signal experts
www.alciom.com

On Oct 14, 6:22=A0am, Eeyore wrote: ...

o

..

2.7V is the lower limit - it supports 2.7-5.5V

kevin

You mean semi-custom ?

We don't have those quantities.

Graham

Well, other factors are now looking like pushing the project back onto a more conventional route besides NXP has IIRC 12 bit ADCs in its slimmed down 8051 derived LPC700 and 900 ranges. Sod the PICs I'm an 8051 expert apparently (or so I was once told).

Graham

What is the magnitude (in bits) of the noise in the system (for whatever you want to call "noise")?

Typical Microchip data sheet. Didn't make it clear AND I looked.

Graham

Sod all noise. Effectively clean DC. Just want the resolution. Doesn't even have to fast. Although this plan is now beginning to look shaky (for entirely other reasons) and plan B or C may be used instead.

Graham

Don't know what kind of control this is but IME, a rotary pot with a 15 mm knob can be reliably set to about 1/350th of the range. That's less than 9 bits.

Wouldn't that be better addressed by some averaging and interpolation in software ? That would get rid of both zipper noise and jitter.

--
André Majorel 
You measure democracy by the freedom it gives its dissidents, not
the freedom it gives its assimilated conformists -- Abbie Hoffman.