Re: [usb] low speed EOP -- clarification

[zx_mei@sina.com]

hi, all

is there anyone who can share the low speed device core?ohterwise, 
how difficult to write one?

----- Original Message ----- 
From: meizx@i...  
To: usb@o...  
Date: Mon, 21 Oct 2002 16:28:34 -0100 
Subject: Re: [usb] low speed EOP -- clarification 

> 
> 
> hi, 
> You understanding of  J state and speed bit time is actually 
> correct.Furthermore,you can refer to Chapter7 table7.1 for detailed 
> electriacal information and section 7.1.11 for detailed data 
> signaling rate 
> information. 
> 
> ----- Original Message ----- 
> From: "Srikanth K S" <skashyap@t... > 
> To: usb@o... 
> Date: Mon, 21 Oct 2002 12:50:18 +0530 
> Subject: [usb] low speed EOP -- clarification 
> 
> > Hello All, 
> > We had a doubt in USB 1.1 spec. section 11.5.1.10. 
> > 
> > USB 1.1 says: 
> > 11.5.1.10 SendEOP 
> > This state is entered from the Resuming state if the 20ms 
> timer 
> > expires. It is also entered from the Enabled state when an SOF 
> (or 
> > other FS token) 
> > is received and a low-speed devices is attached to this port. 
> In 
> > this state, the hub will send a low-speed EOP (two low-speed 
> bits 
> > times 
> > of SE0 followed by one low-speed bit times of J). At the end 
> of the 
> > EOP, the state ends. .................................. 
> > 
> > Our understanding: 
> > When HC terminates the resume signal, it is done by sending 
> > low-speed EOP (two low-speed bits times of SE0 followed by one 
> > low-speed bit times of J). We infer that, 
> > 1. the period of J of this EOP is = 1 low speed bit time (= 8 
> bit 
> > times of full speed) irrespective of the speed of the device 
> and 
> > 2. the signal strength is DIFFERENTIAL 0 for a low speed 
> device and 
> > DIFFERENTIAL 1 for a full speed device. 
> > 
> > Please give your feedback. Thanks in advance. 
> > -------------------------------------------------------------- 
> >  Srikanth Kashyap S. 
> > -------------------------------------------------------------- 
> > But I don't have to know an answer.I don't feel frightened by 
> > not knowing things, by being lost in the mysterious universe 
> > without having any purpose, which is the way it really is, as 
> > far as I can tell, possibly. It doesn't frighten me. 
> > -- Richard P. Feynman 
> > -------------------------------------------------------------- 
> > 
> > 
> 
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