normally your agnd will be connected to your dgnd in one place so both are at the same potential.
On 12/18/2014 5:45 PM, Chad Baker 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] 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] >> <mailto:[email protected]>. >> 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] > <mailto:[email protected]>. > 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.
