Transfering I2S format to 2s complement

Peter Daniel · 26th March 2002, 12:50 AM

Has anyone has a ready circuit for the above application. I found that link: http://www.homestead.com/_ksi0701961...les/i2s-2s.jpg , but don't know how to apply it in a real life (never used that kind of circuits before). I would like to connect my CD-PRO 2 transport and AD 1865 DAC using I2S bus, no oversampling.
Thanks for any help,

Peter

Jocko Homo · 26th March 2002, 03:22 AM

I'm sure you get tired of hearing me say this..............

Use a decent oversampling filter, i.e., something other than a SAA7220.

It works. Really. And it does it all for you. Try it.

Jocko

rfbrw · 26th March 2002, 04:05 AM

Asking for a I2S to 2's complement converter is like asking for railway track to locomotive converter. The two are fundamentally
different and perform distinct functions. Following on from the above analogy I2S. Sony/BB etc are method of moving data from A to B , like a track on which data runs. 2's complement on the other hand is a form of signed number representation as opposed to straight or pure binary which is unsigned.
Example using 8 bits
2's complement 0111 1111 +127
0000 0001 +1
0000 0000 0
1111 1111 -1
1000 0000 -128

i.e MSB =1 number is negative
MSB =0 number is positive

Straight or pure binary

1111 1111 = 255
0000 0000 = 0

The link you gave shows an extract from AD app note AN207. Though intended for a different dac, the circuit will work with the AD1865. You should be able to understand or at least copy it joining-the-dots style with the aid of a datasheet or two. This might help in locating them.

U2a/b D type flip-flop e.g. 74HCT74
U3a/b/c 2 Input Nand gate e.g. 74HCT00

ray

Peter Daniel · 26th March 2002, 05:12 PM

Jocko,
I understand your point of view and respect it. Just recently I've built a DAC with CS8420, DF1704 and PCM 1704. It sounds great. But my search never ends and you can't blame me for curiosity. Since there is so much talk lately about non oversampling designs I'd like to try it myself and then decide what's better. And I wouldn't be suprised if the more simple approach sounds better. We have all seen it before.
As for 74HCT74 flip-flop and 74HCT00 nand gate, any idea where I could find functional block diagram for those chips?

Cheers,

Peter

rfbrw · 26th March 2002, 06:28 PM

Try http://www.philipslogic.com/products/hc/all/

ray.

Jocko Homo · 26th March 2002, 06:43 PM

Since you have tried it, then there is hope for you.

CAPSLOCK has a posting somewhere here today about this zero-oversampling nonsense. It revolves around slew-rate limitations of op-amps.

I solved that problem about 14 years ago........haven't used an op-amp I/V since.

Maybe that is why my stuff sounds the way it does, and I therfore see no reason to go backwards 15 years.

Jocko

Peter Daniel · 26th March 2002, 08:16 PM

Ray, just what I was looking for, thanks.
Jocko, worry not, I'll be all right.

Cheers,
Peter

26th March 2002, 12:50 AM	#1
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	Transfering I2S format to 2s complement Has anyone has a ready circuit for the above application. I found that link: http://www.homestead.com/_ksi0701961...les/i2s-2s.jpg , but don't know how to apply it in a real life (never used that kind of circuits before). I would like to connect my CD-PRO 2 transport and AD 1865 DAC using I2S bus, no oversampling. Thanks for any help, Peter

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26th March 2002, 03:22 AM	#2
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	I'm sure you get tired of hearing me say this.............. Use a decent oversampling filter, i.e., something other than a SAA7220. It works. Really. And it does it all for you. Try it. Jocko

26th March 2002, 04:05 AM	#3
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	Asking for a I2S to 2's complement converter is like asking for railway track to locomotive converter. The two are fundamentally different and perform distinct functions. Following on from the above analogy I2S. Sony/BB etc are method of moving data from A to B , like a track on which data runs. 2's complement on the other hand is a form of signed number representation as opposed to straight or pure binary which is unsigned. Example using 8 bits 2's complement 0111 1111 +127 0000 0001 +1 0000 0000 0 1111 1111 -1 1000 0000 -128 i.e MSB =1 number is negative MSB =0 number is positive Straight or pure binary 1111 1111 = 255 0000 0000 = 0 The link you gave shows an extract from AD app note AN207. Though intended for a different dac, the circuit will work with the AD1865. You should be able to understand or at least copy it joining-the-dots style with the aid of a datasheet or two. This might help in locating them. U2a/b D type flip-flop e.g. 74HCT74 U3a/b/c 2 Input Nand gate e.g. 74HCT00 ray

26th March 2002, 05:12 PM	#4
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	Jocko, I understand your point of view and respect it. Just recently I've built a DAC with CS8420, DF1704 and PCM 1704. It sounds great. But my search never ends and you can't blame me for curiosity. Since there is so much talk lately about non oversampling designs I'd like to try it myself and then decide what's better. And I wouldn't be suprised if the more simple approach sounds better. We have all seen it before. As for 74HCT74 flip-flop and 74HCT00 nand gate, any idea where I could find functional block diagram for those chips? Cheers, Peter

26th March 2002, 06:28 PM	#5
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	Try http://www.philipslogic.com/products/hc/all/ ray.

26th March 2002, 06:43 PM	#6
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Since you have tried it, then there is hope for you. CAPSLOCK has a posting somewhere here today about this zero-oversampling nonsense. It revolves around slew-rate limitations of op-amps. I solved that problem about 14 years ago........haven't used an op-amp I/V since. Maybe that is why my stuff sounds the way it does, and I therfore see no reason to go backwards 15 years. Jocko

26th March 2002, 08:16 PM	#7
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	Ray, just what I was looking for, thanks. Jocko, worry not, I'll be all right. Cheers, Peter

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