Problem with connecting PCM2707 to USb

kiranp · 12th January 2011, 08:30 AM

Hi,

I have rigged up a circuit which is used for USB to I2s conversion..
I am using PCM2707 IC from Texas instruments...

And i have attached the schematic of my board also.. I am facing problems in making it recognized , meant to say that when i connect the PCB onto USB port.. A message pops up on windows saying USB not recognized...

I dont know what fault is in my Schematic.. I cross checked the wiring , the components many times .. but didn't find any mistakes..

Can anyone please guide me in getting the work done...

Thank you,
Kitty

lakeside · 13th January 2011, 05:33 AM

I believe pin 3 (HOST) should have a connection to Vcc.

~Mike

kiranp · 13th January 2011, 08:11 AM

Quote:

Originally Posted by lakeside

I believe pin 3 (HOST) should have a connection to Vcc.

Some designs have it connected to VCC and some to ground.. I tried both combinations but didnt work

rrrremus · 13th January 2011, 08:59 AM

Take a look on the configuration i use for PCM2706.

Uploaded with ImageShack.us

kiranp · 14th January 2011, 04:07 AM

Quote:

Originally Posted by rrrremus

Take a look on the configuration i use for PCM2706.

Thanks for the circuit... But i don find much changes in yours and mine.. Mine is Bus powered and yours is Self powered.

Then you have connected all the Analog Vcc's to 3.3V and i have connected to ground.. I think , this will not be of much concern..

But whats that AND gate doing with that HOST pin???

rrrremus · 14th January 2011, 04:55 AM

The gate is there to prevent HOST detection while the DAC is powered off; the chip can be configured to run bus-powered.
Does your PCM2707 chip oscillate ? Is your USB connector wired correctly ?

kiranp · 14th January 2011, 05:11 AM

Quote:

Originally Posted by rrrremus

Does your PCM2707 chip oscillate ? Is your USB connector wired correctly ?

U meant does the 12Mhz oscillate ?? i checked with an CRO for it i got a near 12MHz oscillation..

USB is wired correctly , is there anyway to check whether PCM is dead or working??

rrrremus · 14th January 2011, 05:34 AM

Yes, i mean if the 12MHz oscillates. The 1M ohm resistor and ~27pF capacitors are critical, the chip will not work without them, even if you see oscillation. Show us a photo of your PCB, maybe we can spot something.

kiranp · 14th January 2011, 05:59 AM

Quote:

Originally Posted by rrrremus

Yes, i mean if the 12MHz oscillates. The 1M ohm resistor and ~27pF capacitors are critical, the chip will not work without them, even if you see oscillation. Show us a photo of your PCB, maybe we can spot something.

I am onto it as a prototype , so my PCB is still on its way... i have a not so good picture of it , but i don think you will be able to track the lines and all sorry....

rrrremus · 14th January 2011, 06:03 AM

That looks nasty. Build a PCB for it.

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13th January 2011, 05:33 AM	#2
lakeside diyAudio Member Join Date: Jul 2008 Location: Northeast Wisconsin	I believe pin 3 (HOST) should have a connection to Vcc. ~Mike

13th January 2011, 08:59 AM	#4
rrrremus diyAudio Member Join Date: Sep 2009 Location: Timisoara	Take a look on the configuration i use for PCM2706. Uploaded with ImageShack.us

14th January 2011, 04:55 AM	#6
rrrremus diyAudio Member Join Date: Sep 2009 Location: Timisoara	The gate is there to prevent HOST detection while the DAC is powered off; the chip can be configured to run bus-powered. Does your PCM2707 chip oscillate ? Is your USB connector wired correctly ?

14th January 2011, 05:34 AM	#8
rrrremus diyAudio Member Join Date: Sep 2009 Location: Timisoara	Yes, i mean if the 12MHz oscillates. The 1M ohm resistor and ~27pF capacitors are critical, the chip will not work without them, even if you see oscillation. Show us a photo of your PCB, maybe we can spot something.

14th January 2011, 06:03 AM	#10
rrrremus diyAudio Member Join Date: Sep 2009 Location: Timisoara	That looks nasty. Build a PCB for it.

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