Can i connect PCM56 to SAA7000???

noyan · 13th February 2011, 06:07 AM

Hi,
I built a PCM56 dac and tried to connect it instead of TDA1540 in my Philips CD104 cd player. Saa7000 is working in 16bit format. But, sound is too high and distorted. I think there is a format difference or something. Any idea?
Thanks

Ken Newton · 13th February 2011, 02:29 PM

I couldn't quickly locate a SAA7000 datasheet, but I should think that it transmits data in I2S format, while the PCM56 DAC requires 16-bit right-justified data formating. If you have a datasheet for the SAA7000, see if the output data format can be programmed to 16-bit right-justified by pulling certain pins high or low..

oshifis · 14th February 2011, 11:35 AM

SAA7000 has simultaneous output, no I2S. The PCM56 is also simultaneous input, so no problem here. But the data format of SAA7000 is offset binary by default (this is the input format of the TDA1540), and the PCM56 accepts 2s complement only. Fortunately it can be set to 2s complement by setting pin 38 of the preceding SAA7020 from High to Low.

noyan · 06:40 PM

Thank you for your replies. Here the datasheets of the components:

SAA7020 - PDFCast.org
Dataheet page - PDFCast.org
datasheet of tda1540 - PDFCast.org

SAA7000 has simultaneous output, no I2S. The PCM56 is also simultaneous input, so no problem here. But the data format of SAA7000 is offset binary by default (this is the input format of the TDA1540), and the PCM56 accepts 2s complement only. Fortunately it can be set to 2s complement by setting pin 38 of the preceding SAA7020 from High to Low.

I believe you are right. Because the sound is very loud and distorted. I tried to find how to set it but unfortunately i could not

Can you explain me please how to do it? Will i set the output of the SAA7000 or SAA7020 and how

Thank you!
Noyan

oshifis · 15th February 2011, 09:08 AM

Hi Noyan,

The output format of the SAA7000 is programmed by the SAA7020, and it is controlled by pin 38 (GAP) of the SAA7020. If this pin is set HIGH, the SAA7000 output format is 2s complement, if LOW, the format is offset binary. So you need to set pin 38 of the SAA7020 from High to Low. This is all, no need to do anything on the SAA7000.

noyan · 15th February 2011, 02:14 PM

Quote:

Originally Posted by oshifis

Hi Noyan,

The output format of the SAA7000 is programmed by the SAA7020, and it is controlled by pin 38 (GAP) of the SAA7020. If this pin is set HIGH, the SAA7000 output format is 2s complement, if LOW, the format is offset binary. So you need to set pin 38 of the SAA7020 from High to Low. This is all, no need to do anything on the SAA7000.

Thank you. But, what will i do with pin38? How to set SAA7020 to low? Please help further...
Noyan

noyan · 04:49 PM

I checked the service manual of the Philips CD104 cdp. The pin no:38 of the saa7020 is earthed

Pin 37 (output of SAA7020) is connected to SAA7000. What must i do with pin 38 to set the SAA7020 from high to low

Ken Newton · 15th February 2011, 05:57 PM

Take an actual reading of the voltage on pin-38 with a DMM or a scope. Make absolutely certain that it is at ground level. It seems that it wouldn't be already grounded if the player is designed to send offset-binary to a TDA1540 DAC. Also, very carefully read your SAA7020 data sheet to make certain about how pin-38 should be set (high or low) for 2s complement.

noyan · 15th February 2011, 06:26 PM

Thanks Ken,
According to datasheet of SAA7020 pin20 is earth. I checked the resistance with multimeter between pin 20 and 38. There is no resistance. It means that leg 38 is earthed. SAA7020 datasheet does not explain how to set it high to low.

Ken Newton · 15th February 2011, 06:49 PM

Okay, then try lifting (desoldering) pin-38 and pull it high by connecting that pin to the positive logic supply via a resistor of roughly 47k ohms.

13th February 2011, 06:07 AM	#1
noyan diyAudio Member Join Date: May 2004 Location: istanbul	Can i connect PCM56 to SAA7000??? Hi, I built a PCM56 dac and tried to connect it instead of TDA1540 in my Philips CD104 cd player. Saa7000 is working in 16bit format. But, sound is too high and distorted. I think there is a format difference or something. Any idea? Thanks

13th February 2011, 02:29 PM	#2
Ken Newton diyAudio Member Join Date: Apr 2003 Location: Eastern Pennsylvania	I couldn't quickly locate a SAA7000 datasheet, but I should think that it transmits data in I2S format, while the PCM56 DAC requires 16-bit right-justified data formating. If you have a datasheet for the SAA7000, see if the output data format can be programmed to 16-bit right-justified by pulling certain pins high or low.. __________________ Ken

15th February 2011, 04:45 PM	#7
noyan diyAudio Member Join Date: May 2004 Location: istanbul	I checked the service manual of the Philips CD104 cdp. The pin no:38 of the saa7020 is earthed Pin 37 (output of SAA7020) is connected to SAA7000. What must i do with pin 38 to set the SAA7020 from high to low Last edited by noyan; 15th February 2011 at 04:49 PM.

15th February 2011, 05:57 PM	#8
Ken Newton diyAudio Member Join Date: Apr 2003 Location: Eastern Pennsylvania	Take an actual reading of the voltage on pin-38 with a DMM or a scope. Make absolutely certain that it is at ground level. It seems that it wouldn't be already grounded if the player is designed to send offset-binary to a TDA1540 DAC. Also, very carefully read your SAA7020 data sheet to make certain about how pin-38 should be set (high or low) for 2s complement. __________________ Ken

15th February 2011, 06:49 PM	#10
Ken Newton diyAudio Member Join Date: Apr 2003 Location: Eastern Pennsylvania	Okay, then try lifting (desoldering) pin-38 and pull it high by connecting that pin to the positive logic supply via a resistor of roughly 47k ohms. __________________ Ken


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14th February 2011, 11:35 AM	#3
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	SAA7000 has simultaneous output, no I2S. The PCM56 is also simultaneous input, so no problem here. But the data format of SAA7000 is offset binary by default (this is the input format of the TDA1540), and the PCM56 accepts 2s complement only. Fortunately it can be set to 2s complement by setting pin 38 of the preceding SAA7020 from High to Low.

15th February 2011, 09:08 AM	#5
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	Hi Noyan, The output format of the SAA7000 is programmed by the SAA7020, and it is controlled by pin 38 (GAP) of the SAA7020. If this pin is set HIGH, the SAA7000 output format is 2s complement, if LOW, the format is offset binary. So you need to set pin 38 of the SAA7020 from High to Low. This is all, no need to do anything on the SAA7000.

15th February 2011, 06:26 PM	#9
noyan diyAudio Member Join Date: May 2004 Location: istanbul	Thanks Ken, According to datasheet of SAA7020 pin20 is earth. I checked the resistance with multimeter between pin 20 and 38. There is no resistance. It means that leg 38 is earthed. SAA7020 datasheet does not explain how to set it high to low.

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