Re: [usb] dout of usb 1.1 function core

[mdennis97@hotmail.com]

Thank you very much,rudi.

I find an interesting thing.In the function 2.0 core,you use SSRAM to 
buffer the input and output data.In the 1.1 core,however,FIFO 
instead.Why?
----- Original Message ----- 
From: Rudolf Usselmann <rudi@a... > 
To: usb@o...  
Date: 14 Dec 2002 10:48:04 +0700 
Subject: Re: [usb] dout of usb 1.1 function core 

> 
> 
> On Sat, 2002-12-14 at 13:02, mdennis97@h...  wrote: 
> > Thanks,rudi.You are right.I made a mistake for these wires. 
> > 
> > I have another question:why some signals of the PL module were 
> not 
> > handled? 
> > 
> 
ie.,token_valid,int_to_set,int_seqerr_set,pid_cs_err,nse_err,crc5_err,rx_s
 
> > ize,rx_done,etc.. 
> > 
> > Regards 
> > 
> > Dennis 
> 
> 
> The USB 1.1 function was derived from the USB 2.0 function. 
> The goal was to have a simple core for embedded applications. 
> Those applications did not have a way to gracefully recover. 
> If to many things go wrong the host will drop the function 
> and you have to unplug and plug back in. 
> Best case you just loose data and rely on higher level protocols 
> to recognize it and deal with it. Other applications may not 
> care so much (mice, cameras ...). 
> Frames with those errors are just ignored/dropped - no recovery 
> is implemented. 
> 
> rudi 
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