Digital audio on parallel port

hugobors · 19th February 2006, 10:18 PM

Hello,

Reading the thread speaking about discrete amp, I had an idea, but is it realisable?????

Why not using the parallel port to output the audio flux in a parallel way, (ok 8 bits but mutiplexed for 16bits and for stereo, the parallel port can handle 2Mbytes/s, it will be sufficient for up to 500kHz sampling rate) make a R2R network and output the analog.

What you think???? Do someone tried this???

Thanks

davidsrsb · 20th February 2006, 05:43 AM

It would work and easy to write a driver for it.

We made a flash memory programmer for one of our products that used a Xilinx cpld on board to do byte to multi-word conversion from a parallel port

2M is pushing most PCs, 1MHz is more realistic. If you want the D/A to be the clock master, then you need to have a write buffer and poll the DAC to find when to send the next data, this will slow things down a lot.. but still enough for audio.

The main problem is that you don't have any isolation from the very noisy PC gnd.

danb1974 · 20th February 2006, 07:07 PM

This was the first "soundcard" I've seen on a pc somewhere around '95. It was 8bit mono (just a R2R network) and there were some games that did support it.

Sparhawk · 20th February 2006, 07:20 PM

That brings back memories... I remember the magic when I first hooked up an 8-bit DAC to the parallel port and actually got music out of it... Anyone remember "mod" files?

guido · 21st February 2006, 05:43 PM

Got a MOD player on my mobile phone (P800)! The kids love that thing playing tunes from sesame-street

danb1974 · 21st February 2006, 07:45 PM

Unfortunately I doubt you can get a stable data rate on the parport. Desktop os'es are not realtime. And giving that a usb dac is a couple of bucks I don't see a point either.

PS: after .mod I recall .s3m files... man they sounded good when a friend got a Gravis Ultrasound card which had wavetable and hw mixing.

davidsrsb · 22nd February 2006, 02:39 AM

Quote:

Originally posted by danb1974
Unfortunately I doubt you can get a stable data rate on the parport. Desktop os'es are not realtime. And giving that a usb dac is a couple of bucks I don't see a point either.

Correct, that is why the logic needs a fifo buffer and the PC to be able to poll the buffer to keep the output queue filled. The clock has to come from the DAC, not the PC

There would be no problem making this DAC 24 bit, the TI USB DAC is 16 bit and rather ordinary performance.

Trouble is that parports are obsolete and going away.

danb1974 · 22nd February 2006, 06:40 PM

A pc gives you spdif and usb. From usb you can go to i2s (use the i2s output from a pcm2707 for example and skip the dac part). Now choose your favourite dac (doesn't have to be a TI if you don't like them) and feed it from whichever source it needs. Much more clean than building a buffer/clock/demux circuit from discrete parts, not to mention a winamp/whatever player plugin.

johnthedoctor · 1st May 2006, 03:05 PM

Is it possible to stream 8 x pulse width modulation data from the parallel port.

19th February 2006, 10:18 PM	#1
hugobors diyAudio Member Join Date: Feb 2002 Location: Nantes	Digital audio on parallel port Hello, Reading the thread speaking about discrete amp, I had an idea, but is it realisable????? Why not using the parallel port to output the audio flux in a parallel way, (ok 8 bits but mutiplexed for 16bits and for stereo, the parallel port can handle 2Mbytes/s, it will be sufficient for up to 500kHz sampling rate) make a R2R network and output the analog. What you think???? Do someone tried this??? Thanks

21st February 2006, 05:43 PM	#5
guido diyAudio Member Join Date: Mar 2002 Location: diepe zuiden	Got a MOD player on my mobile phone (P800)! The kids love that thing playing tunes from sesame-street __________________ GuidoB

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20th February 2006, 05:43 AM	#2
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	It would work and easy to write a driver for it. We made a flash memory programmer for one of our products that used a Xilinx cpld on board to do byte to multi-word conversion from a parallel port 2M is pushing most PCs, 1MHz is more realistic. If you want the D/A to be the clock master, then you need to have a write buffer and poll the DAC to find when to send the next data, this will slow things down a lot.. but still enough for audio. The main problem is that you don't have any isolation from the very noisy PC gnd.

20th February 2006, 07:07 PM	#3
danb1974 diyAudio Member Join Date: Jul 2005 Location: Timisoara	This was the first "soundcard" I've seen on a pc somewhere around '95. It was 8bit mono (just a R2R network) and there were some games that did support it.

20th February 2006, 07:20 PM	#4
Sparhawk diyAudio Member Join Date: Sep 2002 Location: Ontario, Canada	That brings back memories... I remember the magic when I first hooked up an 8-bit DAC to the parallel port and actually got music out of it... Anyone remember "mod" files?

21st February 2006, 07:45 PM	#6
danb1974 diyAudio Member Join Date: Jul 2005 Location: Timisoara	Unfortunately I doubt you can get a stable data rate on the parport. Desktop os'es are not realtime. And giving that a usb dac is a couple of bucks I don't see a point either. PS: after .mod I recall .s3m files... man they sounded good when a friend got a Gravis Ultrasound card which had wavetable and hw mixing.

22nd February 2006, 06:40 PM	#8
danb1974 diyAudio Member Join Date: Jul 2005 Location: Timisoara	A pc gives you spdif and usb. From usb you can go to i2s (use the i2s output from a pcm2707 for example and skip the dac part). Now choose your favourite dac (doesn't have to be a TI if you don't like them) and feed it from whichever source it needs. Much more clean than building a buffer/clock/demux circuit from discrete parts, not to mention a winamp/whatever player plugin.

1st May 2006, 03:05 PM	#9
johnthedoctor diyAudio Member Join Date: Sep 2005	Is it possible to stream 8 x pulse width modulation data from the parallel port.

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