CDROM control KITs VFD version - Page 30

glt · 29th January 2009, 05:04 PM

Well, indeed you need four signals plus ground into OPUS (or any DAC), but I can only find 3 signals from the two CDROM I've hacked: BCLK, LRCLK and Data. No MCLK. But I also have the OPUS Metronome which is a asynch resampling and it does not take the MCLK because it generates its own clock.

If I try hard, I would probably find MCLK somewhere since there has to be a master clock in the CDROM otherwise it will not play music and the spdif output would not work

But I have not looked very hard for master clock since I don't need it.

In the two CDROMs I've hacked, the three signals I need are conveniently located in adjacent pins, so once I find one, the others are right there.

I also have a mini-oscilloscope (the one advertised in this forum for $50) and I can see these signals. The LRCLK is a steady 44.1 KHz square wave. The BCLK looks like a staircase sine wave (maybe because the scope has limited bandwidth since it is not steady) and Data is just data all over the place.

fredlock · 29th January 2009, 05:24 PM

Thanks qlt for clarification. Would the BCLK and SCLK be the same? I would think different manufacturers use different abbreviations, correct me if I'm wrong. Can I email you on this if I get further question? Appreciate it.

Fred

glt · 29th January 2009, 05:59 PM

Sure! Email me.

acid_k2 · 30th January 2009, 03:04 PM

Quote:

Originally posted by glt
The LRCLK is a steady 44.1 KHz square wave. The BCLK looks like a staircase sine wave (maybe because the scope has limited bandwidth since it is not steady) and Data is just data all over the place.

I've noticed the same wave (all but square wave!) in my cdrom, using a 20 Mhz CRT scope. It's a miracle that a DAC is able to use that.

fredlock · 30th January 2009, 10:29 PM

Hi qlt,

You're email is disabled.

glt · 31st January 2009, 01:08 AM

Quote:

Originally posted by fredlock
Hi qlt,

You're email is disabled.

I sent you an email. Don't know what is wrong I think I have the correct settings...

glt · 2nd February 2009, 05:47 AM

Almost done. This one is a bit more transparent :-)

http://picasaweb.google.com/lh/photo...eat=directlink

audio-kraut · 2nd February 2009, 06:35 AM

Quote:

This one is a bit more transparent

one might call it "naked truth"

BTW - how to get usable digital audio from a laptop (slimline) cd rom drive? All the desktop cd'roms I have used have quite well functioning digital (spdif) output.
I have a converter from 50 pin to 40 pin ide, but the only audio out is analog. Any hints?

acid_k2 · 2nd February 2009, 12:03 PM

@ audio-kraut
for digital output, you have to open your cdrom, and try to find spdif or I2S signals. Sometimes it's really difficult... start from analog outputs and trace that signals behind, You'll find the dac IC or a "all in one" IC. Try to find datasheet

and then the digital signals pins...

glt · 2nd February 2009, 06:27 PM

I just opened a slimline CDROM. The controller chip is a Mitsubishi general purpose 16 bit microcomputer. I was able to find the datasheet and (obviously) the I/O pins are just described as generic I/O. Besides, the pitch size of the pins and components are even smaller. In theory, you can check each I/O pin and determine the BCK, LRCK and data lines with a scope. The Microprocessor has a built in DAC.

2nd February 2009, 05:47 AM	#297
glt diyAudio Member Join Date: Oct 2004	My second CDROM... Almost done. This one is a bit more transparent :-) http://picasaweb.google.com/lh/photo...eat=directlink

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29th January 2009, 05:04 PM	#291
glt diyAudio Member Join Date: Oct 2004	Well, indeed you need four signals plus ground into OPUS (or any DAC), but I can only find 3 signals from the two CDROM I've hacked: BCLK, LRCLK and Data. No MCLK. But I also have the OPUS Metronome which is a asynch resampling and it does not take the MCLK because it generates its own clock. If I try hard, I would probably find MCLK somewhere since there has to be a master clock in the CDROM otherwise it will not play music and the spdif output would not work But I have not looked very hard for master clock since I don't need it. In the two CDROMs I've hacked, the three signals I need are conveniently located in adjacent pins, so once I find one, the others are right there. I also have a mini-oscilloscope (the one advertised in this forum for $50) and I can see these signals. The LRCLK is a steady 44.1 KHz square wave. The BCLK looks like a staircase sine wave (maybe because the scope has limited bandwidth since it is not steady) and Data is just data all over the place.

29th January 2009, 05:24 PM	#292
fredlock diyAudio Member Join Date: Jan 2008	Thanks qlt for clarification. Would the BCLK and SCLK be the same? I would think different manufacturers use different abbreviations, correct me if I'm wrong. Can I email you on this if I get further question? Appreciate it. Fred

29th January 2009, 05:59 PM	#293
glt diyAudio Member Join Date: Oct 2004	Sure! Email me.

30th January 2009, 10:29 PM	#295
fredlock diyAudio Member Join Date: Jan 2008	Hi qlt, You're email is disabled.

2nd February 2009, 12:03 PM	#299
acid_k2 diyAudio Member Join Date: Oct 2006	@ audio-kraut for digital output, you have to open your cdrom, and try to find spdif or I2S signals. Sometimes it's really difficult... start from analog outputs and trace that signals behind, You'll find the dac IC or a "all in one" IC. Try to find datasheet and then the digital signals pins...

2nd February 2009, 06:27 PM	#300
glt diyAudio Member Join Date: Oct 2004	I just opened a slimline CDROM. The controller chip is a Mitsubishi general purpose 16 bit microcomputer. I was able to find the datasheet and (obviously) the I/O pins are just described as generic I/O. Besides, the pitch size of the pins and components are even smaller. In theory, you can check each I/O pin and determine the BCK, LRCK and data lines with a scope. The Microprocessor has a built in DAC.

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