Open Source/Freeware Budget USB DAC

[cfavreau]

I think I can help with a driver.

[mixedgas]

I think I can help with a driver.

Hi,

Looks like really good work. What is the status on this project?

Chris, This technology has been superceeded. search for soundcard dac
zoofscope, lazymame, laserboy, zooftennis. Off site search for spehgetti laser software.

Download LFIPLAYER from sourceforge

We now do a lot of this stuff on a 6 or 8 channel USB sound card that costs 25-40$ and a level shifter

This model is known to work:

http://cgi.ebay.com/USB-6-Channel-5-...QQcmdZViewItem

You can also PM drlava about his ezauddac driver, since renamed.

Drlava can also tell you about more freeware and commercial software that works with the soundcard dacs.

More data can be found at laserboy forumns on laserboy but that place can be surreal.

Steve

[drlava]

I could help with a driver.. the reason I hadn't spent a lot more time on this DAC project was that I didn't feel that the microchip mcu had much speed headroom to do more interesting things with. Although I have done development with microchip in the past, clock for clock the atmel series just has more power. Anyways if there is still interest in continuing with the microchip based DAC, a MLD or similar driver interface would definitely be doable.

[dave]

We (Aijii and myself) may be interested in looking into a AVR based solution. The driver would be the catch for us tho, so maybe we could work something here

[weartronics]

Two years ago I did the parts selection and schematic design for a USB-powered DAC based on Philips LPC2148:
http://www.photonlexicon.com/forums/...ead.php?t=3210

However, I never completed the software design (the biggest part of the project), it was easier to make a sound card DAC instead:
http://www.photonlexicon.com/forums/...ead.php?t=6595

I chose 32-bit ARM because I planned to include some simple signal processing and pattern generation in the DAC for music-synchronized visuals without a PC. Since the time of that design, Atmel have brought out AT91SAM7 which makes Philips LPC21XX very ugly by comparison. Also, now there 8-bit AVR parts available with on-chip full-speed USB peripheral - for a simple framebuffer DAC, this is probably enough.

I would strongly recommend against writing a Windows driver. Instead, I suggest designing the firmware so that it can be interfaced using libusb. Then it is easy for any application to address it from Windows (http://libusb-win32.sourceforge.net/) or Linux (http://libusb.sourceforge.net/) without having to write or maintain any drivers. I think it is very important to avoid WDM altogether, because it will take more time than the rest of your project combined!

Another alternative is to use some USB chip with manufacturer-provided drivers, e.g. FTDI. However, the hardware is simpler and cheaper and the software interface is cleaner if you choose an MPU with in-built USB peripheral and interface with libusb.

Best regards,

weartronics

[cfavreau]

Ok here are 3 questions:

1) Is there still a need for an "Open" USB DAC?

2) Is this it? Is this an Open project? Or is there still a need.

3) Is there still a need for an Open API? Some say yes. Some say no. Should I start a thread for that?

A couple of comments. While the LPC chips are nice and fast their development environment and documentation are not great for the hobbiest. They certainly will do the job. I really like the AVR chips however they have the same overhead issue that the PICs have. I have been looking at the Propellor from Parallax. It is 20 MIPs but 8 cpu's in 1 and has a bit of RAM on board. It is also a 32 bit processor(s). And the dev tools are free and there is alot of support for it. Any comments?

If you want AVR... I would suggest one of the FTDI chips (the 245 being the better one for the task) and an AVR or Propellor.

And for the kicker... we could have 2 versions... a PIC version and an AVR version... they are relatively similar in features and should be able to do the job equally well.

Also what is wrong with the Audio DAC stuff?

Chris F.

[cfavreau]

Also one more comment I have.

Being a Laser Hobbiest with a job, I don't have a great deal of time to work on stuff. I really just want to make shows or play... not make tools.

So I think the question would be what is our time best spent on? I think the parallel port DAC did great things for the community... and it is time to create a replacement. Chances are we already have done something that works well and would be good enough to use for everyone. The problem is... once you venture from soldering up a couple of chips to a port on a computer then you get into a territory not all of us can do.

[keeperx]

i believe there is still a need for both an OPEN dac and an OPEN api for that dac.
the sound card is a wonderful thing, but its not perfect.

an open dac with some actual processing power and a frame buffer would be hella cool.
an API that allowed easy incorporation into popular open or free software packages like Spaghetti, LFI player etc etc., or even into commercial players, would also very nice..

I however am not a developer or an electronics guy, but im infamous as a beta tester..

[mixedgas]

Since RIYA are down to 200$, why reinvent the wheel.

Steve

[keeperx]

well thats true.. but its nice to have it out there for someone that wants to build it themselves...

as it stands the API is what would be nice..

I guess you are correct about the riya, but with lasers/projectors becoming more and more common, and nice open source dac and API are inevitable.