Re: [usb] how to detect if a valid handshake is received

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

hi,

host will wait for 16 bit times (USB 1.1) to receive an ACK packet from
the device.

whenever device expects ACK, it will wait for 16 bit times(also called
timeout interval). supposing device has received a corrupted ACK packet
before the timeout interval, it will have to understand that it is ACK
packet. if timeout interval has occured and some corrrupted packet has
been received, then it should be some token packet only but not ACK
packet from the host.

now if host expects an ACK packet, it will wait for timeout interval.
if a corrupted packet is received before this timeout period, host will
have to definitely begin with the same token packet that has been sent
lastly. this is because host will not know whether device has sent ACK,
NAK or  STALL.

r u clear now???

...vikas.



>>> mdennis97@hotmail.com 02/11/03 02:59PM >>>
hi,all

If a device answer no handshake at all,how long a host will wait?
How to identify a corrupted ACK handshake that mentioned in usb1.1 
specifiction 8.6.4?





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