> > *What voltage is the external DC power supply ? Unless the dc power supply > voltage is 1.8v then voltage = value * 1.8 will not make sense.* >
Sorry this is wrong. Values read out of the ADC are in range of 0 to 4095. so . . . voltage = ( value / 4096 ) * scale On Wed, Feb 10, 2016 at 3:05 PM, William Hermans <[email protected]> wrote: > *I have a new BBB. I'm trying to read voltages from a DC power supply. I'm >> having trouble doing so. I connected the output from the power supply to >> AIN0, and the ground from the power supply to the ADC_GND, and tried to run >> the code, but the voltages that I'm reading doesn't make sense.* >> > > What voltage is the external DC power supply ? Unless the dc power supply > voltage is 1.8v then voltage = value * 1.8 will not make sense. > > How this works is voltage = value * scale, where scale is the external > voltage to be measured. So for example if your external powr supply is 12v, > then scale would be 12.0. Just to make sure it is understood however, the > input voltage to the ADC pins must never exceed 1.8v, or you risk at > minimum burning out that pin. > > On Wed, Feb 10, 2016 at 2:54 PM, Chelsea Orefice <[email protected]> > wrote: > >> Hi All, >> >> I have a new BBB. I'm trying to read voltages from a DC power supply. I'm >> having trouble doing so. I connected the output from the power supply to >> AIN0, and the ground from the power supply to the ADC_GND, and tried to run >> the code, but the voltages that I'm reading doesn't make sense. >> >> So I went back to the basic, and just ran the code without plugging >> anything in, and yet the voltage value I'm printing says 1.6 instead of 0. >> Below shows the code, which I got from adafruit. I'm aware that I'm not >> supposed to connect BBB ADC to anything above 1.8V or below 0V, which I >> don't believe I have. >> >> import Adafruit_BBIO.ADC as ADC >>> ADC.setup() >>> value = ADC.read("P9_40") >>> voltage = value * 1.8 >>> print (voltage) >> >> >> >> https://learn.adafruit.com/setting-up-io-python-library-on-beaglebone-black/adc >> >> I've also been reading somewhere that I may have to enable the ADC before >> I can read it?? >> >> Help? >> >> 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]. >> 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.
