Hello all,

I am a biomedical engineering student working on a senior project centered around using a gumstix 400mx as the brains of a redesigned medical device. I've got a buildroot made in ubuntu and have been compiling programs for the gumstix for a few months now. My problem lies with the ability to pull, set, and interrupt the GPIOs. The gumstix site says next to nothing about this and I have only found bits and pieces on the email board.

I have gotten both the GPIO setting code and the GPIO-event program of Dave's, but it seems that when I monitor the gpio-event for any of the gpio's on the Breakout GS board (say LCLK - LDD0) I get an endless stream of events when anything conductive has been touched to the solder pads (even a pencil tip) let less a 5V source. They are in the pattern of FFRRR repeatedly, only limited by the set debounce period.

Is there a certain circuit that should be used here such as pull-up or down resistors? I am not much of an ECE, so I am unsure of this aspect. Also, I have noticed that on the oscilloscope there is a 60MHz carrier on all the GPIO pins mentioned above with reference to the gumstix power supply (presumably from the AC brick). The GPIO's will eventually be used to drive some FETs and poll a quadrature encoder. Thanks.



Joseph R Lust
University of Rochester
Rochester, NY, 14620