Hello, 

I am trying use the Beaglebone Black to monitor a smoke detector 
activation. I have two wires coming from the smoke detector, ground and 
positive lead. The voltage on the wires will go to 0.6v when the detector 
is activated. I have the ground connected to the P9 header GNDA_ADC and the 
positive wire from the detector going to AIN6. When monitoring the base 
values of AIN6 without the detector being activated I get a wide range of 
values. Example output below...

 pin AIN6 value is 2
pin AIN6 value is 105
pin AIN6 value is 0
pin AIN6 value is 0
pin AIN6 value is 687
pin AIN6 value is 195
pin AIN6 value is 29
pin AIN6 value is 1799
pin AIN6 value is 182
pin AIN6 value is 0

When the detector is activated the AIN6 value will just be above 1000. 
However the random base values frequently exceed 1000 as well resulting in 
a lot of false positive activations. 

My questions..

1. Why is there so much variance in the base AIN values when no voltage is 
being applied? Should it not be near or at zero?
2. What can I do to remedy this so I can get consistently low baseline AIN 
values so I do not generate false positive activations?

Please remember - newbie question with very basic knowledge of electronics. 

Thanks



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