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???
07/13/06 18:41
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 		 #120224 - How to do it.
Responding to: ???'s previous message
Two ways.

1. Use a spare pin the PS/2 to USB adapter to feed a signal back to the uC to tell that the adapter is present (or not) and thus you can select the mode. Disadvantage: you need another uC pin.

2. Use the supplied examples from Cypress. BUT in order to do PS/2 and USB on the same pins with just a pass-thru (wiring only) adapter your USB controller must allow you to control the D+ and D- pins and you may need to disable any pullups/downs required for USB speed detection. Plus you can't have any additional pullupsdowns active when USB is selected because that will really foul things up. I doubt (but haven't checked) the D12 will let you do that. I think 80% of the USB keyboard market is Cypress EnCore and that's where you'll find the examples I cited earlier. The Encore allows you to control the pins sufficiently to achieve what you want to do. It's a dog of a micro though. ;-)

GB


List of 28 messages in thread
TopicAuthorDate
Auto-detecting USB and PS2            01/01/70 00:00      
   Power            01/01/70 00:00      
      Power didn't tell            01/01/70 00:00      
         So it's on the same connector ?            01/01/70 00:00      
            I will try            01/01/70 00:00      
            Too long to detect            01/01/70 00:00      
            nope            01/01/70 00:00      
         Mechanical solution            01/01/70 00:00      
            Cable is fixed            01/01/70 00:00      
               How to do it.            01/01/70 00:00      
                  USB Expert            01/01/70 00:00      
            Why not ...            01/01/70 00:00      
         why not put the 'intelligence' into the adapter            01/01/70 00:00      
            Cost/complexity issues            01/01/70 00:00      
               then go the other way            01/01/70 00:00      
                  Still need hardware            01/01/70 00:00      
                     you\'ll need that anyhow, how else?            01/01/70 00:00      
            Agree with Chris            01/01/70 00:00      
               Which is why I suggested Cypress            01/01/70 00:00      
      float to ascii            01/01/70 00:00      
         Start a New Thread and ask again            01/01/70 00:00      
         start a new thread!            01/01/70 00:00      
   Doesn't seem to hard            01/01/70 00:00      
      D+ and D- is not differential at the begining            01/01/70 00:00      
      nope, II            01/01/70 00:00      
   re: autodetect            01/01/70 00:00      
   I bought on of these at radio shack.            01/01/70 00:00      
      speed detect            01/01/70 00:00      

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