Parallel port & laptop

[iroot]

As you know, new models of laptops are without parallel port which we sometimes need for connection to DAC .
I've got HP Pavilion dv6000 with Extension Port. i found on internet this adapter - http://h30094.www3.hp.com/product.asp?sku=2495021&jumpid=ex_r2910_performics/k17401/DDI%20Link#

Does anyone of you ever tried something similiar ?
thank you.

Brano

[buffo]

Hi Brano;

I know that people have not had much luck with USB-to-Parallel port adapters, but this unit is slightly different. If it maps to the correct port in the operating system, it just might work.

Which DAC are you using? I've had some experience with the Alphalite DAC, and I know that it doesn't like adapters of any kind. I've yet to hear from anyone that has found an adapter that it will work with.

Then again, for $30 you can hardly loose. At the very least you'll have a parallel port that you can use to connect your laptop to that old printer you've probably got sitting in a closet someplace!

On the other hand, most of the more modern DAC's use the USB interface.

Adam

[iroot]

Thank you Adam.

DAC which i want to use is from http://pages.videotron.com/legato/La.../LaserShow.htm


i don't wanna spend fortune for USB DAC. for my hobby it is bit too much.
i don't know anything about this adapter. i sent an email to HP but still waiting for answer.

there was another possibility to use this - http://sewelldirect.com/Duel-Systems...IA-Adapter.asp i combination wit PCMCIA card wit parralel port. that should work properly. but it is againg another investment. #
Do you know something about some cheap USB DAC for hobbyst?

[buffo]

DAC which i want to use is from http://pages.videotron.com/legato/La.../LaserShow.htm

Hi Brano;

OK - Cool. That's Norm's Laser Show controller. Norm is a member here on PhotonLexicon. (He goes by "legato" here.) You might want to ask him how his DAC performs with parallel port adapters. Truthfully though, the one you linked to on the HP website has the best chance of working, since it uses the standard multi-I/O port on your laptop. That's the same port that a port replicator uses to give you a parallel port, and those usually work fairly well with other peripheral devices...

My guess is that it will work with Norm's DAC. But if I were you I'd contact Norm first, just to be sure.

Do you know something about some cheap USB DAC for hobbyst?

Well, the words "cheap" and "laser" don't normally belong in the same sentence, but I am aware of 1 USB DAC that you can build yourself for around $50. It's called the bilda DAC. However, the open-source software that it works with will only run under linux. So unless you're fairly savvy when it comes to computers (and linux in particular), you may not want to go that route.

There's also James Lehman's Laserboy project, which uses an inexpensive PCI sound card as a DAC, but once again you need to be running Linux in order to run the software that goes with it.

Finally, I'd like to suggest another alternative - perhaps for some time down the road... Although it sounds expensive, the Pangolin LA Freak package is actually quite a deal. You get the Flashback 3 controller (connects via USB to your laptop) and a complete software suite (the old LA Studio laser show software) to go with it. It includes a live player, a 3-d editor, a text editor, a show editor, an abstract generator... You get the point. It's really nice, and while $500 sounds like a lot of money - in the world of laser show software and controllers, it's a steal. So keep that in the back of your mind...

Adam

[legato]

Hi Brano,

Yes, I'm about 90% sure that device will do the job. It is not like those USB to LPT port comnveters, where SW cannot gain complete and low-level control of I/O lines. That HP device is actually an optional "real" LPT port and should work just fine. Maybe you want to try to ask HP support if it's possible to control all I/O lines by SW.

Regards,
Norm

[sonaluma]

Hello,

The native parallel interface is memory-map on your PCI bus and can achieve high transaction frequency (maybe 500kHz or more) with one byte per transaction (plus some control bits).

The USB interface is restricted to 1kHz transaction frequency (or 8kHz for USB 2.0) and there is some protocol overhead, but you can transmit many bytes with each transaction.

So the parallel port is the 'chatty' interface, to transmit smaller data with higher frequency, and the USB port is the 'chunky' interface, to transmit larger data with lower frequency.

The common low-cost parallel port DAC has no frame buffer or controller, it is just the DAC which receives the points from the computer one at a time and output straight away. So this requires the chatty interface because the interface frequency (in kHz) must be faster than the points frequency (in kpps) and the timing of the signals is very important.

Normally, the USB to parallel port device (designed for printers) uses a special mode with a buffer and controller to receive the print job using chunky USB interface and re-send the print job using chatty parallel interface. Sometims the USB to parallel port device has a special mode, where it looks like a real parallel port to the computer, but this mode combines the data restriction of parallel (one byte) with the frequency restriction of USB (1kHz) so it would not even be possible to achieve 1kpps output.

The "USB DAC" device designed for LASER overcomes this problem using the same technique as the device designed for printer (buffer and controller). It receives the whole LASER frame into the buffer using the chunky USB interface, then the controller output the points one at a time using the chatty interface to the DAC. So this device is actually much more than just a DAC, it is a buffer and controller too.

So in summary, there is no way to use the USB to parallel port adaptor with the cheap parallel port DAC (without buffer and controller).

If you can get a parallel port for your laptop which connects to the expansion port (for docking station) or uses PCMCIA interface, then this is totally different to USB. If it is properly designed, it can work well (like the native parallel port), you have to try.

Otherwise you have to use the "USB DAC" device designed for LASER which has the frame buffer and controller, not just USB to parallel port device designed for printer.

I hope this makes sense, if you have any other questions please ask and I will try to answer.

Kind regards,

sonaluma

[carmangary]

wow, sonaluma, excellent explanation. I definitely learned something by reading that.

But I am curious about something since I have seen a couple USB DACs on the internet. One of them is BILDA. I don't recall seeing any onboard memory or frame buffer capabilities so I don't know how it works if limited to 8Khz transfer rate... or maybe it sends multiple points at a time.

Are you familiar with BILDA? It has a schematic online. If you are a USB engineer I'd love to hear an explanation. I have been wanting to build my own USB DAC for some time now but don't know how.

[sonaluma]

Hi carmangary,

Yes, I have seen the BILDA device on the internet, this device uses Cypress AN2135 controller. This controller has a small amount of RAM internally, which is used for the frame buffer (why there is no external memory chip).

Kind regards,

sonaluma

[dave]

How about the lumax dac?

www.luxax.de

[cruch]

ERR: Correct adress is: http://www.lumax.de/