analog pins not reading correctly

Hello I am so frustrated ,I am hitting ONE piezo (a15 the others are not connected) and you can see in the jpeg what readings I am getting , is this normal? please some advice
this bleeding (electronic crosstalk between pins )makes my project not functional! :’( you can read more here

BLEED.PNG

lexibelle: Hello I am so frustrated ,I am hitting ONE piezo (a15 the others are not connected) and you can see in the jpeg what readings I am getting , is this normal? please some advice this bleeding (electronic crosstalk between pins )makes my project not functional! :'( you can read more here http://forum.arduino.cc/index.php?topic=309300.0

I'm not sure I understand the problem but if you want all those other pins to read a constant value, wire them to something. I suggest maybe ground or to VCC through a 10k resistor.

I'm not sure about the Mega (that is the board you are using, right?) but the majority of multichannel analog to digital converters I have worked with have only one A/D. They get multiple channels by putting a 1 of n selector in front of the A/D. So if the a pin is floating then the A/D may be biased by the previous reading.

Jim.

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