Open Source/Freeware Budget USB DAC

[cfavreau]

Your board is on page 6 right?

http://www.photonlexicon.com/forums/...?t=3225&page=6

(for those just coming in... this post is long no?)

How about developing your board with a DC to DC on it needing 5V input in addition to the DACs and adding a .1 pin dual row header for a crimp ILDA connector on a ribbon cable (makes putting it in a box easier)? I would definitely buy some of those! Plus it would be a great starting place.... no need for the digital pots though... regular ones or no pots would be just fine. Please?

So the board would contain 6 x 12 bit SPI DACs bussed together with 6 slave selects and the LDAC line all bussed together. A 5V to +/-12V? DC to DC converter, all opamps for the analog voltage conversion to differential and maybe some adjustment pots, and finally a connector for an ILDA DB25 on a ribbon. That leaves $55 for the board... ($130 - $85 = $55).

Then we just add controller and firmware/software. Start off with simple firmware/software that just does the basics... point output at up to 60kpps and work from there adding more complexity as we go.

It will be an "open" kit and "budget" all in one!

And... if we find that the controller/platform won't work or we run into a limitation... switch it for another something that will work... that board will work with many many different micros....

[heroic]

Your board is on page 6 right?

http://www.photonlexicon.com/forums/...?t=3225&page=6

(for those just coming in... this post is long no?)

How about developing your board with a DC to DC on it needing 5V input in addition to the DACs and adding a .1 pin dual row header for a crimp ILDA connector on a ribbon cable (makes putting it in a box easier)? I would definitely buy some of those! Plus it would be a great starting place.... no need for the digital pots though... regular ones or no pots would be just fine. Please?

So the board would contain 6 x 12 bit SPI DACs bussed together with 6 slave selects and the LDAC line all bussed together. A 5V to +/-12V? DC to DC converter, all opamps for the analog voltage conversion to differential and maybe some adjustment pots, and finally a connector for an ILDA DB25 on a ribbon. That leaves $55 for the board... ($130 - $85 = $55).

Then we just add controller and firmware/software. Start off with simple firmware/software that just does the basics... point output at up to 60kpps and work from there adding more complexity as we go.

It will be an "open" kit and "budget" all in one!

And... if we find that the controller/platform won't work or we run into a limitation... switch it for another something that will work... that board will work with many many different micros....

That is pretty much exactly my plan... I hoped to have time to do the analogue place and route but I haven't been able to just yet. Major alarm bells ringing at work, all hands to the pump...

[drlava]

What is the benefit of going with a $85 controller board if we are already having to make a board for the analog and interface sections? It seems to be just a + $60 'coolness' factor add on.

[heroic]

What is the benefit of going with a $85 controller board if we are already having to make a board for the analog and interface sections? It seems to be just a + $60 'coolness' factor add on.

Well... I could place the AT91SAM part they're using on the Make board and we could burn it with the firmware they're using; then it would work with their development kit (which is easy to use, kinda like Arduino).

That would get us serious amounts of processing power (ARM is fast, much faster than the AVRs) and not a huge amount more cost. It also has onboard USB so that kills that problem.

[cfavreau]

The point would be to start with a board that has all the surface mount soldering done for us or other hobbiest. It also brings in Ethernet and some other options too plus has a nice software and development chain + tutorials already set up for those that want to tinker. I suppose it is like starting with a USB Audio DAC and then adding the analog bits to adapt it to the ILDA voltage and pinout standard ... except USB audio DAC's are less expensive all around. Is $85 not a good price for those components? The schematic is available ... so it could go on a custom board and be compatible still with the whole tool chain, but then that would defeat the purpose of skipping the hard assembly part.

The idea behind this thread (and device) I thought was a budget open source DAC to output lasers to a projector. I am just trying to keep with the spirit of what I thought the thread was trying to achieve.

[cfavreau]

I would also be willing to buy a couple of the SPI to ILDA boards for this project prototyping and other projects. It would be a good DIY starter base.

[heroic]

The point would be to start with a board that has all the surface mount soldering done for us or other hobbiest. It also brings in Ethernet and some other options too plus has a nice software and development chain + tutorials already set up for those that want to tinker. I suppose it is like starting with a USB Audio DAC and then adding the analog bits to adapt it to the ILDA voltage and pinout standard ... except USB audio DAC's are less expensive all around. Is $85 not a good price for those components? The schematic is available ... so it could go on a custom board and be compatible still with the whole tool chain, but then that would defeat the purpose of skipping the hard assembly part.

*shrug* I can build the board so that you can populate it either way- controller + DAC, SPI DAC only, or controller only. In fact I plan to do that since it is easy. Just add pads for a header and take some care in placement.

[keeperx]

the question is cost vs benefit. a usb sound card dac as X benefit. the dac that is being proposed must have X + Y benefit where the Y benefit out weighs the added cost.

lets list the benefit of each device excluding cost as a benefit

SOUND CARD DAC
USB
can play laser signals (both galvo and color in 24 bit)


I do not know the benefit of the proposed dac so ill let someone else handle that

[heroic]

the question is cost vs benefit. a usb sound card dac as X benefit. the dac that is being proposed must have X + Y benefit where the Y benefit out weighs the added cost.

The future is not built by the lowest bidder.

let's see:

- can run off Ethernet
- can do safety monitoring (startup delay, shutter, interlock, scan fail)
- can do closed loop laser power control
- can run a show off an SD card without a computer
- can run off DMX or MIDI
- can control a status display on the projector
- possible modifications: control TECs, control fans, built-in test patterns, safety zones a la EyeMagic
- can be hacked to do anything else I haven't thought of yet :-)

[cfavreau]

Let me see...

As a point output device the USB Audio DAC would probably be better unless you are a stickler for exact point output rates...

So then to add to that any additional tricks the Open Laser Controller can do add to its value. I see them as:

0) You can do ethernet or USB?
1) You control what is inside it (firmware) .. this can be bad too...
2) It can do lots of stuff in the future as in:
a) DMX output
b) DMX input
c) TTL output/input
d) Audio triggering
e) Standalone operation via SD card ...
f) Scanner safety monitoring
g) The list goes on probably through the whole alphabet and more like a spread sheet.

Anyone want to add to this...