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Message
From: Marc Reinig<mreinig@p...>
Date: Thu Mar 4 16:32:19 CET 2004
Subject: [usb] some question abotu USB
> -----Original Message-----
> [mailto:usb-bounces@o...]On Behalf Of KO TOM
> Subject: [usb] some question abotu USB
> 1. Is that only endpoint 0 can be a inout endpoint ?
An endpoint is the concatenation of the endpoint number and it's direction.
So, there can be two endpoints associated with a given endpoint number (an
In endpoint and an out endpoint). When an endpoint is defined as an IN/OUT
endpoint, it is really a pair of endpoints that share a common endpoint
number. So, it is kind of a misnomer. However, since in common practice,
there is only one IN/OUT endpoint and that is the control endpoint, we just
call it endpoint 0, when technically we should call it the IN/OUT endpoint
pair of control endpoint number 0.
So, no, any endpoint number can be an IN/OUT endpoint. However, I have
never seen any device with more than one control endpoint.
> 2. If some of the endpoint , like endpoint 2, is using control
> transfer . Can it be an inout endpoint ?
It could, but why would you do this?
> 3. Due to the tree architecture of USB, is that my device can
> recieve any packet on the usb bus ? I mean can my device (address
> 3)receive the packets sending to other device (address 2) ? Is
> that all packets are boardcasting?
You will see all packets from the host, and none from other devices.
Marc Reinig
System Solutions
Windows Driver and Embedded Product Consulting
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