[Noisebridge-discuss] Looking to pay someone to build a simple device

Robert "Finny" Merrill rfmerrill at berkeley.edu
Sat Jan 5 06:11:31 UTC 2019


USB peripherals speak when spoken to (with superspeed links there are
apparently some exceptions to this but I'm not familiar and I doubt
playstation controllers are superspeed). This means the protocol is
fundamentally incompatible with one device sharing two hosts.

low, full and high speed USB also uses a fairly high speed
bidirectional differential pair which means that tapping it or
repeating it is nontrivial.

This is not a simple device at all :)



On Sat, Dec 22, 2018 at 12:16 PM Matthew Kleinsmith <mwksmith at gmail.com> wrote:
>
> Hi Henner,
>
> My goal is to duplicate a USB signal coming from a Playstation 4 (PS4) controller, sending one copy of the signal to a PS4 and one copy to a PC; very much like the camera example you mentioned, where both target devices receive the information from the source (camera). My larger goal is to be able to play the PS4 while recording the inputs for later analysis.
>
> "have maybe something listening passively on the other one what is going on"  <--- This is my aim, but I think my understanding is wrong because I interpret your camera example as matching this
>
> On Sat, Dec 22, 2018 at 8:56 AM Henner Zeller <h.zeller at acm.org> wrote:
>>
>> On Sat, 22 Dec 2018 at 02:43, Matthew Kleinsmith <mwksmith at gmail.com> wrote:
>> >
>> > Hey, I'm looking to pay someone $70 plus money for parts to build a simple USB splitter. Is anyone in the Bay Area interested?
>> >
>> > I need it to take a USB signal and then send it to two devices at the same time, and ideally without adding much of a delay. This means one end would be USB female and two ends would be USB male.
>>
>> If you want to send data from the computer to two devices, wouldn't
>> you need two female and one male connect ?
>>
>> What do you want to achieve ? The  USB standard is a bidirectional bus
>> protocol, so if you intend to send/receive data you can do that only
>> from one connection, and then have maybe something listening passively
>> on the other one what is going on. But you can't fundamentally, say,
>> plug in a camera and plug it into two computers and have the image
>> show up on both; or vice versa: have multiple devices receive the same
>> data from one computer. As the protocol is not simply 'sending stuff',
>> but it is a whole back and forth protocol. If you had two devices
>> connected just with some crossover cabling, nothing would work.
>>
>> So the closest to plugging in two devices is to actually use a hub.
>> There is no such thing as an 'Y-cable' that also splits data; you can
>> only use that with power.
>>
>> > When I searched for this device all I found were Y-cables where one line was unfortunately power only.
>>
>> Exactly, and that is the only thing that would work.
>>
>> -h
>
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