Re: [usb] low speed EOP -- clarification

[meizx@ict.ac.cn]

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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