SparkFun Forums

[cwmacier]

Hello,

I have been having an issue with my 24 wire Senring Slip Ring. I split the usb cable of my ELP USB camera and soldered on end of the cable to the spinning side and the usb cable end to the stationary side. For some reason I can't seem to get it to work. I have seen a video on here where a guy uses your Senring 6 wire slip ring to achieve a usb connection. I know he used a USB breakout board to plug into the camera and solder to the slip ring. I am just not sure what he used to go from the slip ring back to USB or back to his computer to receive the signal.

Here is a link to that video: https://www.sparkfun.com/news/1608

I went ahead and got two breakout boards for both sides of the slip ring. one end I will plug the camera into and the other will have a male to male usb cable to run to the computer. That is what I assume this guy did but he didn't really say.

If someone couple please help me out here because I am hitting my head against a wall here.

[cwmacier]

Bump... Still need help guys!

[cwmacier]

Bump again...

[theropod]

Four wires on the usb, right? Unhook all other connections and test for open/short conditions with a multimeter on just those four wires being routed through the slip ring. At least you can tell if the ring is passing current as it should. If it is doing so you can look elsewhere for a fault.

RS

[gbg-medl]

cwmacier,
Were you able to get your USB camera to work? I'm having the same problem. I've tried two different Logitech webcams, and both do not work. All other USB devices do work. It also works with a $1k camera I had laying around.

While troubleshooting, I found that it only malfunctions when the data wires are connected to the slip ring. I tried bypassing the D+ and D-, and only ran the 5+, ground, and shielding through the slip ring. This worked. I tried the opposite (only D+ and D-) through the slip ring, and this did not.

I also tried plugging the camera into the breakout board that was connected to another USB cable that led to the computer. This worked; however, I then connected two wires from the slip ring to the D+ and D- (the other end of the slip ring was not connected at all), and then the USB stopped working.

My preliminary conclusion is that Logitech cameras have some kind of setup that cuts off the signal if it senses the slightest bit of noise from the data lines.

If I can't figure it out, I'm going to find a cheap generic webcam to test.

[Valen]

Have you measured the resistance of the contacts? And voltages of D+ and D-. There might be some voltage drop. D+ and D- need to be at certain levels to tell the host what kind of USB speed device is attached.

Consult 'USB in a nutshell': http://www.beyondlogic.org/usbnutshell/ ... Electrical

[gbg-medl]

Thanks. I measured the resistance and got about 0.2 ohms on both D- and D+. This is with taking into account the resistance through the multimeter cables.

I still do not get it. Here is why:
1) If I solder a usb cable to a breakout board with a usb female jack, and I plug in the webcam (tried 4 now) to the jack, then it works. This is without the slip ring at all.
2) Now, if I connect two of the slip ring wires to the D- and D+ on the breakout board, I get the malfunction notice when I plug the camera into the jack. There is nothing connected to the other end of those two slip ring wires by the way. They are just two wires that go through the slip ring and then terminate. I don't get any sign that these wires are shorting out. I have also tried different wires, and I still get the same result. Its a mystery.

I don't want to purchase another slip ring if I can't figure out what is wrong with the one I have already.

Thanks.

[Valen]

What voltages do you measure on D+ and D- and Vcc (5 volt from USB) against GND with connected slip ring. And a second time with webcam plugged in?

[EDIT: You do also 'slip through' the 5 volt and GND wires right? Not just D+ and D-. Those always need GND for sure.

[EDIT 2: what current is drawn by the camera? That 0.2 ohm could develop enough voltagedrop to cause problems if alot of current is drawn through it.