General discussions about V-USB, our firmware-only implementation of a low speed USB device on Atmel's AVR microcontrollers
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Joined: Mon Jul 22, 2013 2:16 am


Post by semofa » Sat Jul 27, 2013 9:51 pm

hi everybody
I have a problem with the project in the "www.recursion.jp/avrcdc/cdc-232" site .I used the "atmega8" schematic . I did everything that it say but my computer did not recognize it.
when I pull the ground wire ,the "usb device not recognized" message appear on the screen . or if I connect the reset pin in the ground the same message appear , otherwise the computer do not anything . I don't know what am I suppose to do now ...please help me


Re: AVR CDC-232

Post by vouvoume » Sun Jul 28, 2013 12:50 pm

The USB Communication Device Class (CDC) uses bulktransfers for exchanging data with the host.
( http://cscott.net/usb_dev/data/devclass/usbcdc11.pdf )

VUSB only implements USB low-speed devices (1.5Mbps) - bulk isn't allowed there.
Modern operating systems enforce these and therefore VUSB devices using bulk won't work (anymore).

But if somebody has an idea how to overcome this issue (without using an AVR with in-chip USB instead), I am interested in knowing, too.
Please let me know.

Best regards,

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