USB Latency generator

jannievanzyl

Telecoms expert
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Jun 14, 2009
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/Hope this is in the right sub-forum :)

Looking for a "black box" solution that will introduce a configurable latency between an USB host and device. Something that's "plug-and-play". I'm doing it today with a PC and a fair amount of software but really needs something that's idiot-proof. (Something like an RPI with relevant software on it. :) )

I thought it'd be readily available but can't find something like it, suspect not so easy at a low level to introduce latency?

Any ideas, or anyone that could develop something like this?
 

netstrider

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Nov 1, 2006
Messages
2,341
/Hope this is in the right sub-forum :)

Looking for a "black box" solution that will introduce a configurable latency between an USB host and device. Something that's "plug-and-play". I'm doing it today with a PC and a fair amount of software but really needs something that's idiot-proof. (Something like an RPI with relevant software on it. :) )

I thought it'd be readily available but can't find something like it, suspect not so easy at a low level to introduce latency?

Any ideas, or anyone that could develop something like this?
Not entirely sure if I understand you correctly. Is this the direction you are leaning toward?

 

|tera|

Master of Messengers
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Mar 31, 2006
Messages
25,633
/Hope this is in the right sub-forum :)

Looking for a "black box" solution that will introduce a configurable latency between an USB host and device. Something that's "plug-and-play". I'm doing it today with a PC and a fair amount of software but really needs something that's idiot-proof. (Something like an RPI with relevant software on it. :) )

I thought it'd be readily available but can't find something like it, suspect not so easy at a low level to introduce latency?

Any ideas, or anyone that could develop something like this?
Easier method.
Use different lengths of USB cables.
Longer cables, increased latency.
Shorter, less latency. Just an idea.
 

netstrider

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Also found this, not sure how well it works.

 

jannievanzyl

Telecoms expert
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Jun 14, 2009
Messages
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Also found this, not sure how well it works.

This is the concept (and I use some of these for IP networks) but looking for one that does latency insertion in an USB link.

As a practical example, I want to unplug my USB mouse from my PC and plug this box inline, i.e. the mouse goes into the box and a cable from the box into the PC. Now the box must be able to insert a latency in one direction, say up to 100ms.

The practical effect is to show how a small latency affect HMI (human machine interfaces).

Makes sense?
 

jannievanzyl

Telecoms expert
Joined
Jun 14, 2009
Messages
5,140
Easier method.
Use different lengths of USB cables.
Longer cables, increased latency.
Shorter, less latency. Just an idea.
Going to need a moer-of-a-long cable :)

No, I need tens of milliseconds, so a cable won't work. Will need to be something intelligent.
 

netstrider

Expert Member
Joined
Nov 1, 2006
Messages
2,341
This is the concept (and I use some of these for IP networks) but looking for one that does latency insertion in an USB link.

As a practical example, I want to unplug my USB mouse from my PC and plug this box inline, i.e. the mouse goes into the box and a cable from the box into the PC. Now the box must be able to insert a latency in one direction, say up to 100ms.

The practical effect is to show how a small latency affect HMI (human machine interfaces).

Makes sense?
Okay, I understand.

I suppose this should be possible with some form of *nix, but not sure how you will make it portable on an inline device.

Found this on some wiki: /sys/bus/usb-serial/devices/ttyUSB0/latency_timer

Even if possible on Raspberry, you would still need to carry around a monitor of sorts I suppose to show the effects which I guess defeats the purpose unless you get one of them bolt-on LCD screens.
 

Everyones-a-Wally

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Joined
Jul 18, 2008
Messages
51,566
/Hope this is in the right sub-forum :)

Looking for a "black box" solution that will introduce a configurable latency between an USB host and device. Something that's "plug-and-play". I'm doing it today with a PC and a fair amount of software but really needs something that's idiot-proof. (Something like an RPI with relevant software on it. :) )

I thought it'd be readily available but can't find something like it, suspect not so easy at a low level to introduce latency?

Any ideas, or anyone that could develop something like this?
Might be easier to convert to RS-232 or other serial standard and back to USB, then you can play with baud, but then maybe that's a PITA... but then that will affect all throughput, not just introduce latency.
 

ponder

Honorary Master
Joined
Jan 22, 2005
Messages
87,153
/Hope this is in the right sub-forum :)

Looking for a "black box" solution that will introduce a configurable latency between an USB host and device. Something that's "plug-and-play". I'm doing it today with a PC and a fair amount of software but really needs something that's idiot-proof. (Something like an RPI with relevant software on it. :) )

I thought it'd be readily available but can't find something like it, suspect not so easy at a low level to introduce latency?

Any ideas, or anyone that could develop something like this?

Fire a support mail off to FTDI, they might have some ideas/products. I know you can specify latency 1-255ms on some of their usb-serial controllers.

I would also pick some brains over on the badcaps forum.
 

jannievanzyl

Telecoms expert
Joined
Jun 14, 2009
Messages
5,140
Fire a support mail off to FTDI, they might have some ideas/products. I know you can specify latency 1-255ms on some of their usb-serial controllers.

I would also pick some brains over on the badcaps forum.
Thanks, the FTDI link looks promising. I registered to ask on their forum as well. But, good lord, you need to win a quiz show just to register. Check this list of challenge questions just to join their forum...... :)

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