On Fri, 12 Jun 2009 19:35:01 +1000, you wrote: >Sounds like they're just turning the USB power on/off? >That would possibly even do if it was consistent across PCs. >Some main boards have USB always on via jumpers that I have no influence >over. > >I do need to "flash" the contact closure at about 0.5Hz - 2Hz some times. >I'll check out some more USB - micro examples on the web. > >If anyone else has any ideas, I'm all ears. Thank you. >David... I'd guess the cheapest way is to repurpose whatever is the cheapest USB peripheral chip you can find. Mouse/keyboard devices may have some output capabillities (mouse LED control, caps lock LEDs etc.) but may be hard to stop the OS thinking they're real devices) USB-Serial (there are cheaper solutions than the FTDI chip) , using RTS/DTR is one option, but has the snag of figuring out which COM port it's been assigned to. Ditto USB-parallel. Failing that, find whatever is the cheapest USB microcontroller, or do it in software, e.g. http://www.obdev.at/products/vusb/index.html >Charles Craft wrote: >> I did some googling and there are people that want to control USB port power for Wii remotes. >> Seems to depend on the hardware in the PC more than the operating system. >> Some people had luck using the Windows "devcon" command to disable and enable USB ports. >> >> Good luck! >> >> -----Original Message----- >> >>> From: "David Duffy (AVD)" >>> Sent: Jun 12, 2009 3:22 AM >>> To: "Microcontroller discussion list - Public." >>> Subject: Re: [EE] USB to contact closure >>> >>> Just to clarify, what I need to do is close a contact (at various times) >>> under program control, not just when the PC powers up. >>> David... >>> >>> Charles Craft wrote: >>> >>>> Crude but hard to get simpler than a USB controlled plug strip: >>>> http://www.instructables.com/id/A_USB_Power_Controled_Plug_Strip_With_Isolation/ >>>> >>>> >>>> -----Original Message----- >>>> >>>> >>>>> From: "David Duffy (AVD)" >>>>> Sent: Jun 12, 2009 2:47 AM >>>>> To: "Microcontroller discussion list - Public." >>>>> Subject: [EE] USB to contact closure >>>>> >>>>> I have an application where a PC needs to trigger another device via a >>>>> contact closure. The current PCs have serial, parallel and USB ports >>>>> available, but in future one may only have USB. >>>>> >>>>> My first thought was an FT232 USB-serial chip and a small micro driving >>>>> a reed relay, but I'm trying to simplify the design and get the cost >>>>> down as there's potentially 1000 or so units to deploy. >>>>> >>>>> I've never delved into "USB on a PIC" so don't know how easy it is. Also >>>>> bear in mind I have no C language experience. >>>>> >>>>> My other thought was to keep the FT232 and ditch the PIC, simply using >>>>> one of the serial control lines to trigger the relay. >>>>> >>>>> The consequence of erroneously activating the relay during PC powering >>>>> up is not too much of a problem. (I have to confirm this) >>>>> >>>>> Does anyone else have any ideas? >>>>> David... >>>>> >-- > >___________________________________________ >David Duffy Audio Visual Devices P/L >Unit 8, 10 Hook St, Capalaba 4157 Australia >Ph: +61 7 38235717 Fax: +61 7 38234717 >Our Web Site: www.audiovisualdevices.com.au >___________________________________________ -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist