July 30, 2013
about a year ago
As a newbie, I find this thread confusing. I am attaching my MPR121 board to my Arduino Uno via the 3.3V pin supplied on the Uno board, as is done in the Bldr example cited above. Is there anything I have to worry about? Do these comments about 3.3 vs 5V apply only to some other hardware configuration, as I hope?
I enjoyed reading about the Rockwell group and your work in particular, and thank you for sharing your experience. I wondered if you had any thoughts about my posting of earlier today (see below) with respect to adjustment of the touch and release threshold values for the board.
I’m working on my first Arduino project, which uses the MPR121 breakout board with an Indium-Tin-Oxide coated plastic sheet as the proximity detector. I based my code on that available in the Bldr tutorial (http://bildr.org/2011/05/mpr121_arduino/), which appears in turn to use large chunks of the Example Code provided here by Sparkfun. To my pleasant surprise, it all worked, until I installed the ITO plastic pad in its final location, and now the system responds as if the pad is continually being touched. I anticipated this, and assume that the solution is to adjust the touch and release threshold values (TOU_THRESH, REL_THRESH). However, there is no clear guidance as to how to do so, and I find the Freescale documentation daunting to say the least. I’m further confused in that the touch and release thresholds are set, respectively, to 6 and 10 in one example, and 15 and 10 in another (that is, the order of their magnitudes are reversed). I can certainly plunge into lots of experimentation to sort this out, but thought I’d post here first to see if I can cut to the chase by building upon the advice of someone who knows this product well. Thanks in advance for sharing any experience or providing helpful guidance.
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