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

[mdennis97@hotmail.com]

----- Original Message ----- 
From: "Vikas T Rao " <vikasraot@m... > 
To: <usb@o... > 
Date: Wed, 12 Feb 2003 10:15:34 +0530 
Subject: Re: [usb] how to detect if a valid handshake is received 

> 
> 
> 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@h...  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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> I am clear now.Thank you very much.
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