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USB Superspeed Peripherals

Anonymous
Not applicable

Dear All,

   

  We have made a new FX3 PCB based on the EVB, but we have met a problem, when I power up the board, the output power voltage are all right, at the begin of power out, the Crystal can output 19.2MHz clock, but soon the clock will miss, and I have tried to press the reset button, the clock will appear again, but when I release the button, clock will miss again. So my computer also can find the USB device too.

   

 I also think may be the power have some problem, so I used the power from EVB to my board, but have the same problem.

   

 Who ever have met the problem,I think I need some help.

   

Best Regards.

   

Leon.

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5 Replies
prc_1505996
Contributor

Hi,

   

Is your power supply clean, using right Crystal (as per AN70707 recommendation) and is there any damping resistor for Crystal? please share your schematic here if possible.

   

Tnx

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Anonymous
Not applicable

Thank you for your reply.The attachment is our schematic.

   

And I have tried to use the power from the EVB, but it still can not work, and I also used the power from my PCB to EVB,and the EVB can work.

   

Best Regards.

   

Leon

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prc_1505996
Contributor

Hi,

   

    I did a quick review of ur schematic, it looks good to me except USB data lines. Did you run signal quality (Eye diagram test) for this board (if yes, please share)? It looks like FX3 is going to low power mode (may be sleep) due to inactivity in USB port. Please try the following, 1) Configure FX3 PMODE for USB boot. 2) Connect FX3 to USB 2.0 PC through an Analyzer, capture trace and share it here. 3) If you don't have USB Analyzer, probe DP and DM lines and share scope trace. 

   

Tnx

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Anonymous
Not applicable

Hi,

   

I have configured FX3 PMODE for USB boot,but I could not detect any signal in DP and DM lines,it just can detect some changes in DM lines, but after a while,it would be LOW.And in DP line,it is High which output from FX3.

   

Best Regards.

   

Leon.

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prc_1505996
Contributor

Hi,

   

         As I mentioned in my previous post FX3 goes into sleep due to lack of activity in U-port, this is the reason why you are getting Crystal oscillation when you press Reset button and it goes off after sometime. Do more probing on DP/DM ( FX3 connected to HS PC) for enumeration sequence and SOF. Or run Eye diagram test. BTW, what is your USB data trace length?

   

Tnx

   

Tnx.

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