Am 04.03.2014 16:54, schrieb [email protected]: > [email protected] wrote: >> I am reading voltages on AIN0 and AIN1, the voltage on the pins is >> almost exactly 0.9 volts, I have measured it quite carefully with a >> multimeter and this is the voltage I would expect given the dividers >> I'm using. >> >> The raw value from the ADC is 896 (plus or minus a count or two). It >> really is reading the voltage as, if I increase or decrease it a >> little, the reading goes up and down. >> >> However this means that the ADC actually has a full scale reading of >> only around 1800 for 1.8 volts, that's not a 12-bit ADC it's closer to >> an 11 bit one. >> >> Is the ADC set up so that the reading actually represents the voltage >> (i.e. 1800 is 1.8 volts)? >> >> Anyway I think the specification misrepresents the ADC accuracy. >> > OK, I found out what was misleading me. The ADC values that I'm > seeing are the BBB's "non raw" ones which are scaled to be (as I > guessed) the voltage in mV. > > However I can find very little guidance on how to read the actual raw > values, especially from Python. I want to scale the values myself and > using the already scaled 0-1800 values would mean I'm losing a bit of > accuracy. > > Can anyone point me at some Python (or even C if you like) code to > read the real, raw, values? > I only know this example: http://beaglebone.cameon.net/home/reading-the-analog-inputs-adc
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