Aaron Littich

AN3579: Proximity Sensing questions

Discussion created by Aaron Littich on Jan 21, 2008
Latest reply on Feb 3, 2008 by Walter Banks
I was reading the App note, AN3579, which is on freescale's website talking about proximity sensing using the micro's i/o parts to determine when a "touch" sensor has been touched.  At the end of this document it says that this approach should not be used for 'real' applications because the algorithm is not very good.  Does anyone have any ideas on how to make this code or approach usable for the 'real' world? 

I was looking at Analog's capacitance->digital conversion ics for this functionality and they are very complicated it seems to me, plus you have to have a i2c or spi bus to them as well.  Reading their datasheets though, it seems to me their approach is not simply to look for a rise above a certain threshold but to continually monitor all the pins and get a floor level for the surrounding medium to compensate for changes in humidity, etc, and thus the threshold is continually changing. 

Anyone have any ideas?

Not sure if I posted this question in the right forum as it applies to both s08's and coldfires.

Thanks

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