Re: [usb] Zero length data packet?

[Rudolf Usselmann <rudi@asics.ws>]

On Fri, 2002-12-27 at 14:02, vsn@yahoo.com wrote:
> Hi
> Will not the device send NAK packet when it doesnt have data to send?

No NAK is only send in case of an error (PID, CRC, but stuff, etc.)

rudi
> vsn
> 
> ----- Original Message ----- 
> From: "Vikas T Rao " <vikasraot@m... > 
> To: <usb@o... > 
> Date: Tue, 24 Dec 2002 14:39:23 +0530 
> Subject: Re: [usb] Zero length data packet? 
> 
> > 
> > 
> > ** Proprietary ** 
> > 
> > hi, 
> > 
> > the device's endpoint can send zero-length packets for 
> > bulk/interrupt In transcations during any of the following 
> > conditions. 
> > 
> > 1. if the last packet is equal to max. packet size and there is no 
> > further data to be sent. 
> > 2. if the host sends an IN (due to some reasons) even though the 
> > device has sent the last packet less than the max. packet size. 
> > 3. if there is no data available on the device side at all. 
> > 
> > in the last 2 reasons, why host is sending IN and why device has no 
> > data at all, depends on the implementations aspects of host or 
> > device. 
> > 
> > ...vikas. 
> > 
> > >>> skashyap@t...  12/24/02 11:20AM >>> 
> > 
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> 
-- 
rudi
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