USB Do nothing device

Mike201 · Joined: Jan 25, 2009 Posts: 3

Hi All

I want to find a simple way to use USB to detect an on/off condition.

Will a USB device that is either disconnected or connected in the idle state be recognised by the host ?

The enemeration process cannot be completed by the host because my proposed device will not have the capability to respond.

Thanks in advance.

goretsky · Posted: Mon Jan 26, 2009 1:22 am Post subject:

Hello,

Have you considered using a USB to RS-232C/TTL or A/D converter to monitor a circuit? If it is closed, do one thing; if open, another?

At least, that is one possible answer. If you could provide a more detailed description of what you are trying to accomplish I am sure the forum members can provide some suggestions.

Regards,

Aryeh Goretsky

Mike201 · Joined: Jan 25, 2009 Posts: 3

Hi Aryeh
Thanks for the reply

I was hoping to find a really simple way to detect a switch closure on a line that conforms to the USB standard.
The computer would report that a new USB device has been detected or disconnected nothing more.
When a device such as a USB cup warmer is connected then disconnected is the computer aware of those two actions? Does the cup warmer have enough smarts to tell the computer that it there?
I realise that it would be easy to do this with a computer that has a serial or parrallel port but mine doe's not. I was just looking for a lazy quick dirty solution.

Mike

goretsky · Posted: Sat Jan 31, 2009 1:01 am Post subject:

Hello,

My understanding of USB hardware is that they are "smart" devices in that they communicate their device class with the host controller which allows the operating system to identify which drivers are required to utilize the device, much in the way that PnP devices provide information to the host.

You might be able to use a USB to RS-232C or IEEE-1284 adapter to interface a device then poll the serial or parallel port to see if the switch is closed. Another possibility might be to use some sort of microcontroller (Arduino, BASIC Stamp and so forth), although that may be overkill for your project.

I have both a USB cup warmer and a USB cup cooler, but both of them are still in their plastic clamshell packaging. I believe they only have the +5VDC and GND pins connected, while there is no connection to the DATA pins.

Regards,

Aryeh Goretsky

magister-ludi · Joined: Dec 14, 2008 Posts: 12 Location: node 378/15tyc-fg

Is this what you are looking for?

http://www.nirsoft.net/utils/usb_devices_view.html

Mike201 · Joined: Jan 25, 2009 Posts: 3

Thanks magister-lidi
I will try the USB Dview program. I don't think it will do what I originally had in mind but it will be a valuable tool non-the-less.

And Thanks Arhey Gorelsky for the advice. I agree that my idea will not work and consider the subject dead.

I have purchased a Velleman USB interface device (K8055).
The electrical interface required is a piece of cake but I will have to spend some time learning how to program it from Visual Basic.

Thanks again