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Re: [usb] Regarding Frames and Microframes

Title: Message
Hi Thierry,
 
Thanks for your clarification and I expect same kind of help in future.
 
Thanking you once again.
 
Rgds,
Veeresh     
 
----- Original Message -----
Sent: Tuesday, February 26, 2002 3:27 PM
Subject: RE: [usb] Regarding Frames and Microframes

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 �-frame ticks (125 �s) 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:[email protected]]
Sent: lundi 25 f�vrier 2002 19:57
To: [email protected]
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