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USB Enumeration

 
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alexz



Joined: 17 Sep 2004
Posts: 133
Location: UK

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USB Enumeration
PostPosted: Wed Nov 24, 2004 9:15 am     Reply with quote
Hi, I am using the USBN9603 - USB controller and PIC16F877A to develop a USB device.
I receive the 'Get device descriptor request' from the host and after transmitting the first 8 byte setup packet through the Endpoit zero I receive NAK from the host. And the enumeration is obviously failed.
What can be the problem?
Thank you
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Alex
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PostPosted: Fri Nov 26, 2004 7:42 am     Reply with quote
Do you know that the host immediately after receiving the Device Descriptor issues a bus reset?

Check this link:
http://www.beyondlogic.org/usbnutshell/usb7.htm
alexz



Joined: 17 Sep 2004
Posts: 133
Location: UK

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PostPosted: Fri Nov 26, 2004 7:43 am     Reply with quote
Anonymous wrote:
Do you know that the host immediately after receiving the Device Descriptor issues a bus reset?

Check this link:
http://www.beyondlogic.org/usbnutshell/usb7.htm


Yes I know, I get it
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Alex
alexz



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Posts: 133
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PostPosted: Fri Nov 26, 2004 7:45 am     Reply with quote
the device descriptor is 18 bytes.
I send 1rst 8 bytes, receive reset, then get again the request, send twice the 16 bytes in chunks of 8 bytes packets with receiving the ACK between, receive anothe ACK after and when I send the last 2 bytes I get the NAK.
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Alex
alexz



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Posts: 133
Location: UK

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PostPosted: Fri Nov 26, 2004 7:49 am     Reply with quote
I also send a zero length packet after each 8 bytes Tx.
Why does not it acknowlege the last 2 bytes of the descriptor?
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Alex
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