Have it on AGND On Thursday, December 18, 2014 6:46:41 PM UTC-6, cmbaker3 wrote: > > Analog or digital ground? The two are different. > The digital ground will appear to float since the two are not connected. > AGND is at P9-34, whereas GND is P9-1, P9-2, P9-43->46 and P8-1, P8-2. > > Chad > > On 12/18/2014 11:44 AM, [email protected] <javascript:> wrote: > > 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 > > > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > > >
-- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
