Subject:
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Re: NXT - ARM7's and USB
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 8 Jan 2006 21:36:28 GMT
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Viewed:
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1461 times
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In lugnet.robotics, Chris Magno wrote:
>
>
> Im not a chip guru, can someone explain why the lego speck says the USB
> is input only? The PDF's for the ARM7 chip set(s) this could be, state
> the on board USB controller is bidirectional.
>
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> questions, questions, questions.....
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> Chris
Chris,
I know little about USB, but USB communication is not peer to peer like an
ethernet port. You have masters and slaves, or hosts and devices. Whether you
are host or device, you still need to be able to communicate bidirectionally.
If the host writes to the device, the device must receive data. If the host
reads from the device, the device must send data.
The host vs device issue has to deal with higher level protocol issues, and
probably has an impact on how much hardware is involved. Some USB interfaces
can be either host or device, but most are either host or device but not both.
It sounds like the USB on NXT is device only. My understanding is that
cabling workarounds cannot change this USB to host capabilities.
Kev
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Message has 1 Reply:
 | | Re: NXT - ARM7's and USB
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| In lugnet.robotics, Kevin L. Clague wrote: Your on the right track but your terminology is a little off. USB like many of the next generation protocols is indeed point-to-point. However, the problem is at the protocol level (as you start to point (...) (18 years ago, 9-Jan-06, to lugnet.robotics, FTX)
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Message is in Reply To:
| | NXT - ARM7's and USB
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| Im not a chip guru, can someone explain why the lego speck says the USB is input only? The PDF's for the ARM7 chip set(s) this could be, state the on board USB controller is bidirectional. questions, questions, questions..... Chris (18 years ago, 8-Jan-06, to lugnet.robotics)
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