looking for suitable microcontroller

Hi,
I don't think what i'm planning could ever be described as a robot, but I guess you people are best placed to help me out. I am looking
for a microcontroller that will give me a whole bunch (six actually, or multiples of six) analogue outputs that i can interface to a PC to give me values between 0 and +5v on each channel.
The idea is to build a virtual lighting desk that runs on a laptop and interfaces to the standard lighting controller cable which usually sits between the lighting board and the dimmer racks.
From the reading around I was doing last night the Brainstem running in slave mode will do what i want, but I don't need any of the advanced features and on-board processing that it provides. The device will only ever run slaved to the laptop. I don't need any inputs, only analogue outs. It would be nice if the device was USB and self powered, but i don't want to push my luck :)
Interestingly, looking at the Brainstem and OOPIC R, I can't help thinking that they look really cool devices and a whole heap of fun. I may have to get one just to play around with :) People don't tend to talk about the Acroname Brainstem as much as the OOPic R, is this just because OOPics are more established? The features and price of the Brainstem and OOPic R looked pretty similar to me...
thanks for your help
Jim
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I think you will be hard pressed to find true analog out on a micro. Typically that is done with separate D/A converter chips. I have been playing with a burr brown 7612U, that has on board ref. Don't recall if it is 5V or 4.096V though.
the other way to get voltage out, it to integrate PWM with an integrator circuit.
Mike

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There are LOTS of microcontrollers with analog out.
MC68HC11, MC86HC16, MC86HC332 Lots od PICs, lots of AVRs, etc etc etc...
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- Alan Kilian <alank(at)timelogic.com>
Bioinformatics Applications Director, TimeLogic Corporation
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Alan Kilian wrote:

Alan:
I'm by no means an expert across the entire PIC line, but the closest I've run into for voltage out is the setable voltage reference on the PIC16F628. Could you suggest a few PIC and AVR part numbers that have D/A outputs?
Thanks,
-Wayne
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Arggggh, Gaaaaaaaaa... (Cough, cough) Did I REALLY do this??????? Of course, I read A/D, not D/A !!!!!!!!!!!! Arrrgggghhhhhh...... So, I know of not one micro with analog OUT. Sorry, my brain went non linear for a moment.
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Alan Kilian wrote:

Just checking. ;-)
-Wayne
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I feel better now... I went to Microchip, Motorola, thinking I had lapsed in time. Found some cute micros though.
I think I remember reading somewhere that the analog issues on the same die as the uC can be difficult.
Again, an op-amp , couple of resistors, and a cap, can integrate PWM, but I prefer SPI. Even there, it seems as though there are less choices than there used to be somehow.
Mike
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Mike:
I think getting a real D/A is better than integrating a PWM signal. Since I prefer to work with DIP packages and 5 volts, there are not many options available. One option is the TLC5620 which is a 5V Quad SPI 8-bit D/A available in both SOIC and DIP packages. It is $3~$4 from Digikey in quantity 1.
Enjoy,
-Wayne
P.S. To contact me directly, snipped-for-privacy@PacBell.Net won't work; use Wayne -at- Gramlich DOT Net instead.
Blueeyedpop wrote:

[snip]
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Wayne C. Gramlich wrote:

Maxim has a nice line of DACs, and give free samples for some of their products. They have a nice 32 channel 16 bit DAC if you don't mind using SMD.
http://para.maxim-ic.com/compare.asp?Fam C&TreeConverters&HPCDACRef.cfm&ln James
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[snip]
Some of the MicroConverters by Analog Devices have analog out, but I think the maximum is two channels. 8051 core, flash, and SPI/I2C.
Jeff.
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Jeff Shirley
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Maybe you just need a USB DAC instead of a microcontroller.
Serial-port 4-channel $269 http://www.superlogics.com/specpage.asp?Items 24
USB 2-channel industrial $1200 http://www.apogeedigital.com/products/minidac.php
USB 4-channel $140 http://www.j-works.com/jsb682.html
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Does the dimmer rack talk DMX512? That may be another option..
HTHs Greg the Grog
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Mike suggestion elsewhere of using PWM and integrating the output to achieve a voltage is a good one, but I think you might need more accuracy and less drift. (Of course you could always compensate for component variances in software.) Separate DACs might do it, and some offer I2C and SPI interfaces. Another approach is the digital potentiometer, many of which are interfaced via SPI. You could scale this up in groups of six quite easily. Some are dual and quad, so you don't need separate chips for each channek.
Cost for digital pots is about $3-4 each, less if you look around, and sometimes they show up on surplus. Most of the ones I've seen (like from Maxim) are in SOIC packages, so I hope you're good at soldering! <g>
-- Gordon Author: Constructing Robot Bases (Forthcoming) Robot Builder's Sourcebook, Robot Builder's Bonanza
Jim wrote:

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