|Subject:||Re: [Paparazzi-devel] adcs and sensors|
|Date:||Mon, 7 Feb 2011 19:24:26 +0100|
While trying to make my imu run I have realized there are a lot of things I don’t understand well. I hope someone could give me a hint, or somewhere to get this info..
I know paparazzi has a 10bit adc, that means the availability of discerning up to 1024 values-from 0 to 1023.
I know sensors have an operating voltage, a typical reference output and a sensibility. (and lots of parameters more).
For instance, an accelerometer is said to output Vs/2 when sensing 0g. Then, it has a sensibility of 300mV/g and can measure +-3g.
I wonder how to associate the 1023 values of paparazzi with the +-3g extreme measurements. Only via setting a neutral and a sensitivity? I think I should read Vs/2 when 0g, and Vs/2 should be related to a number from 0 to 1023, in this case maybe 512…but is always 0 and 1023 related to 0 and 3.3V(being 3.3V the reference voltage in the mcu? Or it depends in the output range of the sensor?)
And what about the sensibility? Which are the objective units after the operation sensibility*(raw_data-neutral)? In adc values or in physical values? I suppose this sets the sensibility parameter units, for instance g/adc unit, or mv/g, or something else…
I know nothing makes sense, so I really would be pleased if someone could help me a little.
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