USB Wiring to PCB If anyone is still confused about where what wire goes to here is your answer.
http://putfile.com/pic.php?pic=11/31611275512.jpg&s=x11
carpespasm- 11-13-2005
shouldn't the sheilding also be connected to 10?
mhawk134- 11-13-2005
I didn't connect the shielding to any of mine and they all work fine. I may be wrong but I think the sheilding is like a extra ground. So I don't worry about it.
BillW- 11-13-2005
The USB spec actually specifies not to ground the shield on the device side. This is supposed to avoid ground loops.
OTOH, I did a bit of reading on this style of shield grounding, and it appears that it can sometimes be worse than no sheilding at all depending on the cable length, since it can act like an antenna.
Personally, I've never bothered to ground the sheilding and I've never had any problems with any of my cables.
The first thing I'd do with a bad cable would be to check the solder joints - make sure that you're maximizing the amount of signal getting through. Then as a last resort I'd ground the sheilding, to minimize the noise.
mhawk134- 11-13-2005
OOOOooooooooo in your face carpespasm. Just kidding. But thanks for enlightening me on the sheilding part. I didn't know about a grounding loop though.
carpespasm- 11-13-2005
ok, i shall stop giving out bad advice on that then, sorry guys
BillW- 11-13-2005
ok, i shall stop giving out bad advice on that then, sorry guys
I don't think it's bad advice - I believe the ground loop thing is only a problem when the USB device is plugged into an AC outlet. (EE types - am I wrong?)
And if I wasn't clear, the antenna-effect I'm complaining about is what happens with the official USB spec arrangement. If you connect the device end of the shield to ground, as you suggest, the antenna effect goes away.
I give the "connect the shield to ground" advice myself whenever somebody has obvious cable problems. It's easier to give them it as a quick fix because it *should* reduce the noise, which will likely get them going. It's much harder to convince someone they may need do a better job of soldering when they're positive the cable is fine because it "works to enumerate" or "works to open in Ops" or even "works to unlock".
All of that said, the only reason I brought it up was to point out that device-shield-to-ground wasn't the official way of doing things, nor was it a necessary evil - but I still believe it's a useful thing to do when all else fails.
carpespasm- 11-13-2005
all right, good to hear the full story on it, i have done it and assumed pretty much that it was a good idea to do since i've seen it done in some regular usb devices, where the outer shell of a usb-b connector would be grounded
texaspyro- 11-13-2005
Shield ground I think connecting the shield ground on the camcorder seems to work better. A friend had a flakey cable/camcorder/computer problem that de-flakeified when we connected the shield. In the wacky world of ad-hoc USB interfaces your mileage may vary...
brite_eye- 11-14-2005
Does it make any difference connecting shield to 10 versus 7 or 2? Or are 10,7,2 all connected? Probably easy to trace on MUOTUC schematic but I am being lazy.
carpespasm- 11-14-2005
i beleive that someone mentioned a while back that 7 is a "cleaner" ground, where as 10 is just a ground any given component on the board can drop to.
that being said, i've seen many say they've had no ill-effect with using 10 for the usb ground and all. you can look at the board and see that 10 is connected to a large common ground though
uncooper- 01-19-2006
i am using a usb B (4-pin) port. how do i know which pin corresponds to which "color"? or, in other words, what is the direct pinout from a usb b female connector to the pcb? it looks like this (crappy ascii diagram coming right up):
-----
|1 2|
|3 4|
|___|
^------------female usb b port opening
Meh, i hope this makes any sense...
caterpillarclub- 01-19-2006
usb pinouts You answer can be found at:
http://www.connectworld.net/usb.html
USB female pinouts are
2 1
3 4
Signal Color Pin
+Data Green 3
-data White 2
VCC Red 1
GND Black 4
Re: Micr usb connector I ended up attaching a micro usb connector to my CVS camera.
Who are you using to make the small circuit boards? I have several small boards I want to build, but most proto houses screw you over on the per piece cost since they won't panelize them without an outrageous charge.
Forumer™ is Voted #1 Free Forum Hosting provider
Build your own community today with the largest message board hosting company.
