Can't get PCM2902 to work

Limhes · 5th February 2007, 02:37 PM

I'm trying to make a PCM2902 USB sound card, using the (almost exact) schematic from the data sheet. Made a PCB, all connections are correct (as far as I can see) and there are no shorts. But, when I connect the device, Windows won't recognize it. I keep getting the message that there is a USB device connected, but it is not recognized.

You can find the schematic in the data sheet.

The PCB I made is attached, with and without silk screen. Does it matter that I used electrolytic capacitors instead of non-polars for the 1uFs? I replaced both ICs and it still doesn't work. There is a fine 5V USB voltage on the chip, but the !SSPND pin doesn't get high. I can't measure the crystal's signal, since I have no scope at hand. Is this very critical to layout?

Thanks in advance.

Limhes · 5th February 2007, 03:21 PM

Hmm, I can't edit the above post...

But, I just saw I didn't connect SEL1 and SEL0 to the positive supply voltage. But, even after doing that, it doesn't get recognized.

sexya · 29th April 2008, 05:09 PM

i feel you need to swap the data pins probably you have mixed those up.. that why its not getting reconz.. i had some thing like lthis when i was fixing my mp3 player data cable and i had mixed up piins.. i am talking of the data + and data - pins not + vcc and ground... mind it.

andreask · 30th April 2008, 08:21 AM

Hello Limhes,

check if your oscillator is working.

If not, try different values for the capacitors near the crystal.

You need a scope to see if the oscillator is working properly!

Andreas

gmarsh · 30th April 2008, 02:22 PM

The 1Mohm resistor in parallel with the crystal has to be there.

I left this out on a PCM2906 design, it would detect as a USB device in this case but wouldn't go any farther, same as what you're seeing.

Archwn · 3rd May 2008, 02:26 AM

For the record. Electrolytic caps can be used with no problem. Even the modest Nichicon Muse FW.

I suggest 10uF would do the job. I didn't say it is the best to use electrolytic though.

Some reports that after pull in/out for a while, this guy might just wake up and work at anytime.

As I can't see the posted pictures, I can't comment.

5th February 2007, 02:37 PM	#1
Limhes diyAudio Member Join Date: Apr 2005 Location: Nijmegen!	Can't get PCM2902 to work I'm trying to make a PCM2902 USB sound card, using the (almost exact) schematic from the data sheet. Made a PCB, all connections are correct (as far as I can see) and there are no shorts. But, when I connect the device, Windows won't recognize it. I keep getting the message that there is a USB device connected, but it is not recognized. You can find the schematic in the data sheet. The PCB I made is attached, with and without silk screen. Does it matter that I used electrolytic capacitors instead of non-polars for the 1uFs? I replaced both ICs and it still doesn't work. There is a fine 5V USB voltage on the chip, but the !SSPND pin doesn't get high. I can't measure the crystal's signal, since I have no scope at hand. Is this very critical to layout? Thanks in advance.

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5th February 2007, 03:21 PM	#2
Limhes diyAudio Member Join Date: Apr 2005 Location: Nijmegen!	Hmm, I can't edit the above post... But, I just saw I didn't connect SEL1 and SEL0 to the positive supply voltage. But, even after doing that, it doesn't get recognized.

29th April 2008, 05:09 PM	#3
sexya diyAudio Member Join Date: Jun 2007 Location: Bombay/India	i feel you need to swap the data pins probably you have mixed those up.. that why its not getting reconz.. i had some thing like lthis when i was fixing my mp3 player data cable and i had mixed up piins.. i am talking of the data + and data - pins not + vcc and ground... mind it.

30th April 2008, 08:21 AM	#4
andreask diyAudio Member Join Date: Jun 2004 Location: Mainz	Hello Limhes, check if your oscillator is working. If not, try different values for the capacitors near the crystal. You need a scope to see if the oscillator is working properly! Andreas

30th April 2008, 02:22 PM	#5
gmarsh diyAudio Member Join Date: Apr 2004 Location: Halifax, NS, Canada	The 1Mohm resistor in parallel with the crystal has to be there. I left this out on a PCM2906 design, it would detect as a USB device in this case but wouldn't go any farther, same as what you're seeing.

3rd May 2008, 02:26 AM	#6
Archwn diyAudio Member Join Date: Oct 2006	For the record. Electrolytic caps can be used with no problem. Even the modest Nichicon Muse FW. I suggest 10uF would do the job. I didn't say it is the best to use electrolytic though. Some reports that after pull in/out for a while, this guy might just wake up and work at anytime. As I can't see the posted pictures, I can't comment.

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