Relay switchable USB hub?

**JimmyFitz** · 03-15-2008, 01:30 PM

Originally Posted by BarryWoods

As long as you have the iPod as the active usb device it will charge. Once you switch over it won't any more. Now if you just switch the io pins and not the power pins, when you switch over it will go from a usb data port to a usb charging port. Though I don't know if you head unit can supply enough power for both devices.

Your circuit looks like you have the right idea. You could try Not switching the power lead like Barry says if you want both to charge at the same time. But that may be more likely to make the Kenwood host not see the swap of devices. Trial and error will get you an answer to that.

**BAC5point2** · 03-16-2008, 09:57 AM

One of the ports will only be for USB thumb-drive, so I won't have any reason to charge both ports at once. I'll likely just switch all 3 wires and ground the 4th. I suppose I could actually even use the 4th pole to switch ground too, right? That's only a little more soldering...

Still, I need a flush-mount USB connector. I can't find any commercial 2 port hubs that are large enough to house a 4PDT relay. So I'll make my own, but I don't want it to look ghetto. Plus, I need to mount a USB port in my center console, and don't want that to look bootleg either.

Ideas on that?

**JimmyFitz** · 03-16-2008, 11:44 AM

Originally Posted by BAC5point2

One of the ports will only be for USB thumb-drive, so I won't have any reason to charge both ports at once. I'll likely just switch all 3 wires and ground the 4th. I suppose I could actually even use the 4th pole to switch ground too, right? That's only a little more soldering...

Still, I need a flush-mount USB connector. I can't find any commercial 2 port hubs that are large enough to house a 4PDT relay. So I'll make my own, but I don't want it to look ghetto. Plus, I need to mount a USB port in my center console, and don't want that to look bootleg either.

Ideas on that?

http://store.mp3car.com/Automotive_M..._p/com-040.htm

I wouldn't switch the ground wire.

**BAC5point2** · 03-16-2008, 05:21 PM

I saw that, but I want something small so I can fit it on a small project box that'll be behind the dashboard. I need 3 of them (so I don't have to hardwire the iPod connector and the other connector to the switch unit).

You wouldn't switch ground? Fair enough, it's easy to run a ground wire.

**BAC5point2** · 03-24-2008, 01:48 PM

So would you use this:

http://www.newark.com/64K3142/electr...EW-HC4-H-DC12V

and this:

http://www.newark.com/64K3145/electr...C-EW-HC4-SFD-K

I'd like to build this fairly soon. I still don't know exactly how I will build the module though.

Does anyone have a USB pinout chart?

**kelmk** · 03-24-2008, 01:51 PM

I just built a relay into a usb cable for my space navigator. The only wire I had to switch was the red power wire. switching it off caused the device to not be found. I don't think it is necessary to switch the other wires.

**JimmyFitz** · 03-24-2008, 02:06 PM

Originally Posted by kelmk

I just built a relay into a usb cable for my space navigator. The only wire I had to switch was the red power wire. switching it off caused the device to not be found. I don't think it is necessary to switch the other wires.

Glad to know that you got it working. The OP wants to toggle between two devices. Killing power to one device will definitely inhibit it, but the reason I suggested switching the I/O lines too was that there would still be a chance of the unpowered device interacting through those lines with the device that you are trying to use. The best way to guarantee that ANY two devices you may wish to plug in and switch between works is to simulate unplugging one and plugging in the other. Grounds would not matter but power and I/O are all that's left.

**BAC5point2** · 03-24-2008, 02:18 PM

Actually, I don't need a 4PDT, so how about these:

http://www.newark.com/35K3220/electr...HRACK-PT370012

and

http://www.newark.com/46F3616/electr...UMFIELD-27E893

I have a question about the orientation of the pins though.

I found this

http://relays.tycoelectronics.com/datasheets/PT.pdf

For the 3PDT relay.

Can I assume that pins (13) and (14) are used for the coil, and that I'd wire the USB pins from the head unit to (4), (5), and (6), and then wire the thumb-drive input to (1), (2), and (3) and the iPod input to (7), (8), and (9)? I've never used a dual-throw relay before, only SPST's.

Thanks!

**W3bMa5t3r** · 03-24-2008, 02:48 PM

If you're still looking for the USB Pinouts, this is one of the best sites I've found for almost ALL pinouts. It's a russian site (I'm guessing), but it's in english.

http://pinouts.ru/SerialPortsCables/...e_pinout.shtml

**BAC5point2** · 03-24-2008, 03:56 PM

I found a USB pinout on Wiki, but that site is unbelievably awesome!

Any information about the wiring of the 3PDT relay I mentioned above?

You are in DC? I'm just north of DC!