Simple ADC

Lafet

Hi,

How it is possible please simply read voltage on resistive divider - potentiometer? I need potentiometer regulate engine speed.

Very thanks, Lafet

Mike Green

Have a look at the circuitry on the Propeller Demo Board for the microphone. There are demo programs in the Propeller Object Exchange for microphone to VGA and microphone to headphones which illustrate how to use this for ADC. Also look at the Propeller Education Kit lab on the counter modules.

deSilva

If you only want to determine the value of a resistor, the Education Counters Lab will be fine for you:

BTX

Hi.
I did it using RCTime object, similar schematic as deSilva.. but don't·forget to insert a serial resistor in the I/O pin to be used, then make some touchs at the RCTime code, to get·better stability with the potentiometer control.


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Regards.

Alberto.

deSilva

Oh, Alberto, I think loading the cap with 40mA is quite o.k.
Just take a smal one: 10 nF and 10k will be fine.

BTX

Sorry deSilva.... once more time I don't understand your mean... but mine, is to avoid get a "0" Ohm R directly to gnd & directly to the I/O pin.
You could fried the I/O pin in that situation. Look at the RCTime object....it has that R=220 Ohm in serial with the I/O pin to use.
So for that case, if the R value of the potentiometer -> 0 => Imax in the I/O pin will -> 15mA... only.

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Regards.

Alberto.

deSilva

You are right Alberto, It will not even work with 0 Ohms in the first place