|
Message
From: Bo <bo_ye@y...>
Date: Tue, 26 Feb 2002 15:17:42 -0800 (PST)
Subject: RE: [usb] Regarding Frames and Microframes
What will happen if the transaction reach the
1ms boundary? Does the host insert the SOF
packet and redo the current transaction, For
example "Bulk in transfer"?
regards
bo
--- Thierry LEROUX <tleroux@e...> wrote:
> Hi,
> These frames are "token only" transactions. They do
> not need any ACK or NAK
> to be handled.
> There is a 8 bits PID + 11 bits of frame # + 5 bits
> CRC (= 3 Bytes).
> The Frame # is a 11 bits system wide time frame. Use
> of it is function
> dependent. You can imagine to use it to maintain a
> common system wide time
> frame (For example to synchronise audio equipments
> ...).
> The "tick" time is 1 ms.
> In addition, there is µ-frame ticks (125 µs) if the
> function is 2.0
> compatible. In that case you need some local
> computation to create a 15 bits
> counter.
> We found this SOF very useful for synchronization
> over the whole bus and
> between connected devices.
>
> I hope this help.
>
> Thierry
>
> -----Original Message-----
> From: Veeresh [mailto:veeresh@u...]
> Sent: lundi 25 février 2002 19:57
> To: usb@o...
> Subject: [usb] Regarding Frames and Microframes
>
>
> Hi all,
>
> I am Veeresh newly joined this mailing list.
> While going through the
> USB Spec. 2.0, I got some doubts in Start Of Frame
> (SOF). As these frames
> are token only transactions, what is the
> significance of these frames? What
> the 11-bit frame indicates?
>
> Thanks and regards,
> Veeresh
>
>
|
 |
Browse
