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Autocalobrate issues with MPR121- dead inputs occaisonally after startup

Question asked by johncohn on Feb 15, 2014


   I'm using MPR121's for a large musical instrument. the whole instrument is made up of 6 different keyboard structures each with an MPR121 and an Arduino Mega.. all in all it works quite well. The issue I'm having is with the autocalibration   routines. At startup, I use the MPR121 autocalibrate to automatically set the operating point for each of the 'keys' . Generally it works great. and all  6 keyboards come up wiht all 11 keys on each working. .  Occasionally, however  one or two of the units will come  with 1-3 keys that are not working.. I can always clear the condition by doing a full power on reset a time or two, but that's inconvenience. Any idea why I'm getting this flaky behavior ? Could I have the thresholds set wrong or something ?   Thanks for any quick help.. This thing goes on the road in 2 weeks !




I've attached a copy of the MPR121 register settings I'm using..

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