Blog pruposal - Page 1
Forum section: electronics / general

author: dirtycookie
author_rank: Newbie
timestamp: March 07, 2012, 05:51:09 pm
content: Hi,I wanted to know if there could be a blog about considering to develop a logic bus sniffer that could sniff an usb.There are projects out on the web like the ones from dangerous prototypes.I think there are various ways to accomplish this, but what are they? What are the pros and cons?Maybe it could be demonstrated in a blog?

author: Bored@Work
author_rank: Super Contributor
timestamp: March 07, 2012, 08:01:13 pm
content: Cons: High speed USB 2.0 is 480 Mbit/s

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 07, 2012, 09:17:08 pm
content: Quote from: BoredAtWork on March 07, 2012, 08:01:13 pmCan't we hack the Rigol for that?

author: dirtycookie
author_rank: Newbie
timestamp: March 11, 2012, 06:44:41 pm
content: I understand that getting into the MHz range, things get tricky. But what are these problems??Such effects should be discussed and elaborated a little more rather than discussing the Anti Static Bag in an episode.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 11, 2012, 08:06:25 pm
content: Quote from: dirtycookie on March 11, 2012, 06:44:41 pmIf you think it is easy, why do you need a tutorial, why don't you just do it instead?

author: Andy
author_rank: Contributor
timestamp: March 11, 2012, 08:21:07 pm
content: Quote from: BoredAtWork on March 11, 2012, 08:06:25 pmThinking it is easy highlights his lack of knowledge in the area. Hence his original question, "But what are these problems?"

author: SgtRock
author_rank: Unknown
timestamp: March 12, 2012, 02:34:27 am
content: Greetings EEVBees:--Dear Dirtycookie:--Welcome to our humble blog. You said:"Hi, I wanted to know if there could be a blog about considering to develop a logic bus sniffer that could sniff an usb. There are projects out on the web like the ones from dangerous prototypes.I think there are various ways to accomplish this, but what are they? What are the pros and cons? Maybe it could be demonstrated in a blog?"--I understand what you are asking, so do not pay any attention to unjust accusations. Try as I may, I am unable to find the word "easy" or the word tutorial in your statement. Perhaps someone who knows more than you or I, will have a go at discussing some of the salient points pertinent to your inquiry, without giving you the beans. There really is no excuse for abusing a beginner for asking a question. In any case, stick around, it does get better."When people thought the Earth was flat, they were wrong. When people thought the Earth was spherical they were wrong. But if you think that thinking the Earth is spherical is just as wrong as thinking the Earth is flat, then your view is wronger than both of them put together."Isaac Asimov 1920 - 1992

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 12, 2012, 09:37:42 am
content: Commercial USB sniffing equipment already exists, but it is expensive not only due to the hardware requirements, but also the hugely complex software that must be developed along side it.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 12, 2012, 12:54:59 pm
content: Quote from: Andy on March 11, 2012, 08:21:07 pmCome on, we all know what this is really about. Full-service mentality.He is to lazy to even figure out what the problems are, and doing just a minimum of research into the problems. But instead expects to get a solution spoon feed, for a $20 USB hardware sniffer by tomorrow, made from an old smelly sock and an Arduino.

author: dirtycookie
author_rank: Newbie
timestamp: March 12, 2012, 07:16:17 pm
content: I never said that the subject would be easy to explain, nor am I asking to "spoon feed" me a solution here. Ofcourse there are expensive solutions on the commercial market.Ofcourse this is no easy subject, but would be interesting to discuss, and here you could try to use my proposal or not, about trying to scratch into the 1MHz range and show all the influences (like thermo and em) that make things difficult and expensive. Those influences might be very complex to discuss...And I don't know what you mean with "full service mentality", but I understand from these words that you are getting some how personal where I don't see the reason why.

author: T4P
author_rank: Super Contributor
timestamp: March 12, 2012, 07:31:53 pm
content: Quote from: dirtycookie on March 12, 2012, 07:16:17 pmIF you surfed around recently you would have noticed what a person BAW is

author: Bored@Work
author_rank: Super Contributor
timestamp: March 12, 2012, 07:58:18 pm
content: Quote from: dirtycookie on March 12, 2012, 07:16:17 pmA blog entry is not a discussion. You haven't spend a millisecond to research the problem, but want to have a solution served on a plate. Don't make up that "discussion" excuse. For a discussion you would have to bring something to the table. But lets try that "discussion" thing. What do you think of the eye diagrams in the USB spec?

author: vk6zgo
author_rank: Super Contributor
timestamp: March 26, 2012, 02:56:52 am
content: This impinges upon a thing that has been "niggling" for a while.Whatrealbandwidth does a USB signal occupy?I don't mean"pretend"bandwidth in Mbits/sec,I'm talking about what amount of spectrum it would occupy when looked at with a Spectrum Analyser.All the references I can find on the 'Net are for IT people,& don't go into the actual implementation of the system.Everything about USB cables,etc indicate that it isn't really 400MHz wide,so it would seem that it uses sophisticated modulation methods,& isn't just a "Super RS232" sort of thing.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 26, 2012, 07:57:50 am
content: Quote from: vk6zgo on March 26, 2012, 02:56:52 amThe USB spec has some 50 or 100 pages about the electrical signal in the main 600 page (or 1000 page, I don't remember) spec. The signal is specified via eye diagrams. [Guess why I asked the poster about his opinion of that part of the spec?]From the eye diagram you should be able to derive the minimum required signal rise and fall time.QuoteYou should be able to estimate the spectrum from the signal.QuoteJust read the original spec. You can download it from usb.org. It consists of some 20 documents, the main spec being 600 pages. And that was one of my points. If you want to know about USB you don't have to wait for a video blog, you can get the spec right now. If you are willing to invest some of your own time, instead of expecting a full service blog.QuoteHigh speed does require 90 Ohm (or was it symmetric 45 Ohm?), and it needs to be good enough to guarantee the required USB signal quality. I don't remember if the spec also gives a bandwidth.QuoteI don't think I saw that in the 2.0 spec. But you can check for yourself.QuoteUSB is for sure tricker than RS232. One of the reasons embedded programmers still like to stick to RS232 when they can. And if they can't, they like to stick a serial-to-USB chip into the system to avoid having to deal with all of USB.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 26, 2012, 09:08:41 am
content: What a nightmare!Looking at the eye diagrams,it does look as if it occupies that kind ofrealbandwidth.Looking at USB cables,though,it seems counter-intuitive,as they are not that high-tech.One place I worked at used non standard cable with hand soldered 4 pin plugs & sockets to pipe USB signals around a piece of equipment.The Engineer who bought the cable said it had better specs than normal USB cable,but it freaked me out a bit.It certainly didn't look like HF wiring to me!It may have been USB1 though,so the requirements would be less harsh.From the info on the website,I don't see the OP making his device any time soon!