Dave did a very thourough and professional design for the CVS. Much kudos, of course. He
has also very generously published his code and figured out use of the interupts and
explained them in his notes. I want to publicly extend my thanks for his generousity.
All you really need to start playing with a Basic Atom Pro and a synthesizer is one output
DAC. You should put a 10K ohm resistor in series with the analog inputs in case you go
below zero or above 5 volts, but the entire design is not required.
Just the votage reference and one DAC chip could be built on perf board without too much
problem. The ultra deluxe model is very nice, but you could build something up in steps
rather than go for the whole thing at once.
--- In ComputerVoltageSources@yahoogroups.com, laxt57@... wrote:
>
> Hi
> Wow!!! Very impressive, maybe beyound the capabilities
> of lots of diyers. Really I/O rich. I was really thinking of something
> more modular. Maybe with the Atom core on a mother board
> and the I/O as daughters(sisters?)
> Jeri
>
>
> -----Original Message-----
> From: davebr@...
> To: ComputerVoltageSources@yahoogroups.com
> Sent: Mon, 5 Feb 2007 9:09 PM
> Subject: [ComputerVoltageSources] Schematics posted
>
>
> I have uploaded into the Files>Hardware section my set of schematics.
> I did not post these previously because I did not originally generate
> them. I only took other's ideas and draft schematics and enhanced
> them with ideas from this group and some of my own. I believe everyone
> is in agreement that they should be posted now. I would like to thank
> Grant Richter, Harry Bissell, John Loffink and others who have posted
> comments and made input. I also want to thank John Loffink for his
> contributions to the LCD_Support module.
>
> I originally built all portions of these schematics to validate them.
> I purchased an AtomPro28 to evaluate and understand it since
> BasicMicro still has not released a datasheet. I also purchased many
> of the parts to prototype and validate functionality such as the I2C
> interface. I also purchased a front panel to verify the LCD_Support
> module mounting.
>
> Like many of you, I wanted an advanced module and decided the only way
> to get one was to build it myself. Since I already has well over $200
> invested, I decided to complet a PCB design over Christmas and built
> it last month. I have written a 16 step sequencer program (1762 source
> lines) that uses 75% of the program memory. I have spent hours with a
> scope and protocol analyzer determining how the I2C and serial ports
> really work. Details of my module are documented on my web site at
> http://modularsynthesis.com/cvs/cvs.htm
>
> Having completed my module, I am now on to other projects. One of the
> many is a remote I2C interface with a keypad and additional controls
> for improved user interface. There are several videos on my website.
> I would suggest you view the videos of the LCD display. It adds
> awesome capabilities to the module and is why I am now designing a
> better user interface.
>
> My PCB is not for sale. I designed a 4x6" PCB with a ground plane and
> SMT components. There are over 50 wires to the front panel and another
> 50+ wires on the front panel. The ground plane clearance is 0.012
> inches. The PCB is very difficult to solder and once all the wires are
> connected it is nearly impossible to access for troubleshooting.
>
> I would, however, be happy to offer suggestions to anyone who wants to
> carry forward a PCB design that is more reasonable to build. Here is
> my initial list of suggestions:
>
> 1. Decide on a group consensus for the feature set. This particular
> set of features cost over $500 in parts alone.
>
> 2. Decide on a panel and do a PCB for the jacks and controls.
> Soldering over 100 wires was not fun nor practical for may DIY'ers.
>
> 3. Decide on an appropriate DAC. I chose the DAC7715U since it was
> less expensive than the DAC8420 with a savings of ~$40.00. This DAC
> is in shortage and distributors are not expected to have parts until
> after August 2007. You may also find that stock has been depleted on
> the DAC8420 as well. You probably want to use the DAC8420 so you can
> get it in the DIP package. Laying out dual package styles is not
> really feasible.
>
> 4. The LED drivers are simple current sinks and I used amber LEDs.
> Basically they are on, dim, or off so they only tell you that an
> output is doing something. This portion of the design could be
> improved.
>
> 5. My power supply noise comes right through into the input buffers
> when viewed on a scope. I can see digital ambiguity of +/- 1 count on
> my A/D conversions. This could be due to the noise, the inexpensive
> potentiometers, or the accuracy of the H8/3664 processor. I can't
> troubleshoot it any further because I can't access my board (due to
> all the wires). You might consider adding 12 volt regulators for the
> op amps. I adapted my software to input average the A/D conversions
> over the last four cycles and is reasonably stable.
>
> 6. The display module is a must-have (watch the videos). The I2C works
> very well. The hardware interrupt serial support works very well for
> MIDI. Having programmable MIDI capability enables a whole new set of
> features and having serial communications enables synchronizing
> multiple modules (there is a video of this as well).
>
> 7. Standardize on a design that has software compatibility. The
> advantage of a group design is the ability to build upon other's
> software contributions. Anyone wanting a 1 to 16 step sequencer has my
> application as a starting point.
>
> 8. Use my analog input layout for a starting point. I compressed the
> circuit as small as possible with standard power buses so I could step
> and repeat this for all the channels.
>
> Best of luck to anyone who volunteers to complete the design of a PCB.
> I suggest you be the final "voice" in determining the feature set.
>
> Dave
>
>
>
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