Soundcard from Scratch

[Xer0]

Man, your are a genius!

Never seen something so before. What kind of plug do you use? seems quite long to me...

Too bad that almost all of the really good Showsoft including Spaghetti and HELS are on Windows, while Linux always had the more hardware level access. Great that you can even use the Input Pins there!


Building a DAC from Scratch, thats what im currently thinking aobut too. I would need a fast µC with SPI, some 16 bit DAC's and lots of Knowlegde. But what would be the most usefull Device Class it should use? something what every Windows, Linux and MacOS could handle withoout drivers i need...

[blowfly]

I'm guessing the Pangolin stuff uses all proprietary drivers. It would be interesting to hear from those guys how many man-hours have gone into their drivers.

On buying vs. building, I think it all depends on what your goals are. There are several different levels where you can put your energy including hardware, software, laser presentations, event production, etc. At each level there is a spectrum of choices for DIY or throwing money at the problem. I think if you enjoy building hardware and hacking drivers, then by all means build it all yourself. If you love grinding sand to make silicon, go for it!

Mike

[weartronics]

Building a DAC from Scratch, thats what im currently thinking aobut too. I would need a fast µC with SPI, some 16 bit DAC's and lots of Knowlegde. But what would be the most usefull Device Class it should use? something what every Windows, Linux and MacOS could handle withoout drivers i need...

I suggest that you don't implement any specific device class. I think you need to do some more reading about the USB specification before you can make this decision.

I'm guessing the Pangolin stuff uses all proprietary drivers. It would be interesting to hear from those guys how many man-hours have gone into their drivers.

Not to belittle the work of the DAC manufacturers, but it's not writing the driver in general that's difficult. The difficulty of writing a new Windows driver for the C-Media DAC arises from features which are specific to the USB audio device class interface.

[Xer0]

I not always want to reinvent the Wheel. using stuff for other purposes as desired is my usual ideology, like the SoundCard DAC. my most problem with all is my perfectionism, i often beginn to go into detail too far and with all the planning dont find the time to make it, so i even more often just throw money at it
so i bought a complete scanner from china and hope to build my own soon one day when i get more time...

But i like to experiment and have lots of dreams. With learning µC's i always wanted to start some day, so developing a simple usable DAC, at first just with the minimum required features, would be a lovely goal!

[cynikal]

Yes, it would!

Attachment 14290

I have investigated at least half a dozen of the popular USB ILDA DACs, and none of them have working Linux drivers; evidently there is no demand for this. Rather than design an entirely new DAC for this purpose, I wrote a Linux driver for the C-Media chips so that a) audio applications don't see them as sound cards and accidentally cause galvo movement or laser emission, and b) a simple laser frame based API can be used, with the PCM generation and buffering abstracted inside the driver.

At the same time, I used the GPIO pins to get the ILDA return input signal (pin 12) and set the ILDA shutter output signal (pin 13), and I used a shift register with the micro-controller interface to provide eight TTL outputs for beam or effect actuators on the user-defined signals (pins 9-11, 21-24). It would be possible to use the same micro-controller interface for more comprehensive DMX or TTL input/output, but eight TTL outputs is all that fits nicely on the ILDA connector.

This approach seems to work well. In fact, because there is no dead-time between frames, you actually get higher average brightness and faster animation rates than any commercially available USB ILDA DACs. At the moment I'm still using the blue box prototype that many of you have seen, but I will be producing a few more for other projectors using the board above, which integrates the C-Media circuitry along with the differential amplifiers inside a DB-25 enclosure.

a nice little layout of a pcb, looks promising.. any progress with this ? was it feasible? could you make it into a commercial product (or at least release the schematics/pcb layout/parts list please) ? software would be nice too

[weartronics]

a nice little layout of a pcb, looks promising.. any progress with this ? was it feasible? could you make it into a commercial product (or at least release the schematics/pcb layout/parts list please) ? software would be nice too

Hi cynikal, I built a few of them and they work well. In fact, they work better than various commercial DACs I have! Zero off-time between frames means that I get uninterrupted abstracts, higher frame rates, and higher average brightness than any of those.

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Unfortunately it's not commercially available because the Linux user base is too small to justify it, and I have no plans to develop a Windows driver at this time. I have only produced a few for internal use.

The user-mode Linux driver works with any CM106 or CM6206 based card. If you would like a copy, please email me http://www.weartronics.com/contact.php and I would be pleased to send it to you. Of course, the TTL outputs and shutter/return signal won't work without extra circuitry, but differential X Y I R G B outputs should work fine.

If you are planning to build your own card, you might like to copy my "blue box" design. I got the idea from Andrew Kibler (drlava) and James Lehman's amplifier board, but I designed it to fit in the sound card case, I reduced the DC-DC to +/-5V for increased output current, I built differential amplifiers for all channels, and I eliminated many unnecessary pots. Unfortunately I never drew the schematic, but you could refer to the original design, or you may be able to copy the layout and wiring from my proto board here. Otherwise, I know other members are selling various sound card amplifier kits and boards here.

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