How to safely test USB connector installation

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Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

Okay, I admit it, I've screwed it up before and I don't want to do it again.
I have several Single Board Computers that have SBC headers on them and I
have to run a commercial cable from the headers to a standard USB chassis
connector. The polarity of the USB header isn't obvious on some of these
boards and I have destroyed the USB interface on one of them by plugging a
device into the USB with the header on rotated 180 degrees. I don't want to
do this again.

How can I test a USB setup in a (completely) non-destructive manner? I'm
more than comfortable using DVMs and even oscilloscopes but I really don't
know what I can measure that will assure me that the connector is on the
board correctly.

TIA
Norm
 
Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

"Norm Dresner" <ndrez@att.net> wrote in message
news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> Okay, I admit it, I've screwed it up before and I don't want to do it
again.
> I have several Single Board Computers that have SBC headers on them and I
> have to run a commercial cable from the headers to a standard USB chassis
> connector. The polarity of the USB header isn't obvious on some of these
> boards and I have destroyed the USB interface on one of them by plugging a
> device into the USB with the header on rotated 180 degrees. I don't want
to
> do this again.
>
> How can I test a USB setup in a (completely) non-destructive manner? I'm
> more than comfortable using DVMs and even oscilloscopes but I really don't
> know what I can measure that will assure me that the connector is on the
> board correctly.

Well, if you download the USB spec from www.usb.org, you can see which
contacts carry the 5V. So you can measure with a DVM whether these contacts
carry 5V in the right polarity. You can then safely plug in a device to see
if the polarity of the datalines was ok or not.

Meindert
 
Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

"Norm Dresner" <ndrez@att.net> wrote in message
news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> Okay, I admit it, I've screwed it up before and I don't want to do it
again.
> I have several Single Board Computers that have SBC headers on them and I
> have to run a commercial cable from the headers to a standard USB chassis
> connector. The polarity of the USB header isn't obvious on some of these
> boards and I have destroyed the USB interface on one of them by plugging a
> device into the USB with the header on rotated 180 degrees. I don't want
to
> do this again.
>
> How can I test a USB setup in a (completely) non-destructive manner? I'm
> more than comfortable using DVMs and even oscilloscopes but I really don't
> know what I can measure that will assure me that the connector is on the
> board correctly.
>
> TIA
> Norm
>

I'd make a test cable. Cut up a USB cable and add some resistors and LEDs
between vcc and ground. Have a GREEN led light up for a good connection and
RED for bad. Then plug it into your SBC and check for a green light before
you connect any USB devices.

You can work out which pins to use on here
http://www.starmount.co.uk/s_usbpin.htm

Peter


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Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

"Meindert Sprang" <mhsprang@NOcustomSPAMware.nl> wrote in message
news:10qr4v16v7tjb2b@corp.supernews.com...
> "Norm Dresner" <ndrez@att.net> wrote in message
> news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> > Okay, I admit it, I've screwed it up before and I don't want to do it
> again.
> > I have several Single Board Computers that have SBC headers on them and
I
> > have to run a commercial cable from the headers to a standard USB
chassis
> > connector. The polarity of the USB header isn't obvious on some of
these
> > boards and I have destroyed the USB interface on one of them by plugging
a
> > device into the USB with the header on rotated 180 degrees. I don't
want
> to
> > do this again.
> >
> > How can I test a USB setup in a (completely) non-destructive manner?
I'm
> > more than comfortable using DVMs and even oscilloscopes but I really
don't
> > know what I can measure that will assure me that the connector is on the
> > board correctly.
>
> Well, if you download the USB spec from www.usb.org, you can see which
> contacts carry the 5V. So you can measure with a DVM whether these
contacts
> carry 5V in the right polarity. You can then safely plug in a device to
see
> if the polarity of the datalines was ok or not.

Sure -- but without experience with that bus, I wasn't sure that this
would be a "perfect" test. If you're right -- and the next poster has a
really nice suggestion of making a test cable with LEDs (and resistors, of
course), it'll be trivial to check every board from here on out.

Thanks
Norm
 
Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

moocowmoo wrote:
> "Norm Dresner" <ndrez@att.net> wrote in message
> news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
>
>>How can I test a USB setup in a (completely) non-destructive manner? I'm
>>more than comfortable using DVMs and even oscilloscopes but I really don't
>>know what I can measure that will assure me that the connector is on the
>>board correctly.
>
> I'd make a test cable. Cut up a USB cable and add some resistors and LEDs
> between vcc and ground. Have a GREEN led light up for a good connection and
> RED for bad. Then plug it into your SBC and check for a green light before
> you connect any USB devices.
>
> You can work out which pins to use on here
> http://www.starmount.co.uk/s_usbpin.htm

You also could buy a cable tester. This will normally test RJ-45, RJ-11
(phone jack) and USB. Today they are relatively cheap.
 
Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

"Trygve Selmer" <trselmer@start.no> wrote in message
news:41AE220B.6020704@start.no...
> moocowmoo wrote:
> > "Norm Dresner" <ndrez@att.net> wrote in message
> > news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> >
> >>How can I test a USB setup in a (completely) non-destructive manner?
I'm
> >>more than comfortable using DVMs and even oscilloscopes but I really
don't
> >>know what I can measure that will assure me that the connector is on the
> >>board correctly.
> >
> > I'd make a test cable. Cut up a USB cable and add some resistors and
LEDs
> > between vcc and ground. Have a GREEN led light up for a good connection
and
> > RED for bad. Then plug it into your SBC and check for a green light
before
> > you connect any USB devices.
> >
> > You can work out which pins to use on here
> > http://www.starmount.co.uk/s_usbpin.htm
>
> You also could buy a cable tester. This will normally test RJ-45, RJ-11
> (phone jack) and USB. Today they are relatively cheap.

I've seen RJ-45, RJ-11, and coax testers but never noticed a USB one. I'll
have to check my preferred supplier's catalog again.

Thanks much for the suggestion.

Norm
 
Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

Norm Dresner wrote:
> "Trygve Selmer" <trselmer@start.no> wrote in message
>
>>You also could buy a cable tester. This will normally test RJ-45, RJ-11
>>(phone jack) and USB. Today they are relatively cheap.
>
> I've seen RJ-45, RJ-11, and coax testers but never noticed a USB one. I'll
> have to check my preferred supplier's catalog again.

Mine is called Skymaster Remote Cable Tester DCJ-0102 (made in Taiwan),
testing RJ-45, RJ-11, USB and BNC (coax).

Link to the new version of this tool:
<http://www.fonitech.com/catalog/product_info.php?cPath=57&products_id=476>

Trygve
 
Archived from groups: comp.arch.embedded,comp.os.linux.hardware,comp.sys.ibm.pc.hardware.chips (More info?)

"Norm Dresner" <ndrez@att.net> wrote in ...
> "Meindert Sprang" <mhsprang@NOcustomSPAMware.nl> wrote ...
> > "Norm Dresner" <ndrez@att.net> wrote ...
> > > How can I test a USB setup in a (completely) non-destructive
> > > manner? I'm more than comfortable using DVMs and even oscilloscopes
> > > but I really don't know what I can measure that will assure me that
> > > the connector is on the board correctly.
> >
> > Well, if you download the USB spec from www.usb.org, you can see which
> > contacts carry the 5V. So you can measure with a DVM whether these
> > contacts carry 5V in the right polarity. You can then safely plug in a
> > device to see if the polarity of the datalines was ok or not.
>
> Sure -- but without experience with that bus, I wasn't sure that this
> would be a "perfect" test. If you're right -- and the next poster has a
> really nice suggestion of making a test cable with LEDs (and resistors,
> of course), it'll be trivial to check every board from here on out.

Kensington sell a USB-powered LED-on-a-stick which would seem to do the job.
http://www.kensington.com/html/1176.html
 
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