Re: [usb] Info Reqd

["Vikas T Rao " <vikasraot@myw.ltindia.com>]

hi,

either by h/w or s/w, sending packet limited to max packet size can be
done. only difference is, s/w takes a lot of time to do it while h/w
does it 100 times(this figure depends on the system) faster. since h/w
is faster, it is only preferred for USB timing.

..Vikas Chandra Rao T.

>>> sinax_usb@yahoo.com 02/14/03 11:05AM >>>

Hi All,
I am writing a USB2.0 Device Stack.At present i dont hav any hardware
so i am simulaing a few h/w functionalities in s/w itself.
For h/w functional referene i used the "ARC USB CONTROLLER CORE"
document.
My understanding after reading the document as to what a device does
when it has some data to send is :
When the device has a Data to send, it will update the Control Register
with the address of the buffer that has the data.The h/w when it
receives an IN token, looks at the control register of the corresponding
endpoint.If the buffer address is valid it will transmit the data
pointed by the buffer.
My question is:
Every endpoint has a Maxpkt size.If the data to be sent to the host is
more than Maxpktsize for that endpoint, who will take care of sending
the pkts whose size equal to maxpkt size.Is it h/w or s/w
responsibility??
The s/w can just point to the buffer that has the data, without
bothering abt the size of the data, will h/w send the data as multiple
maxsize pkts??
Thanks and Regards,
Srinivas
 



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