I am trying to create a GUI that would let me output a certain increment of a digipot (AD5242 1Mohm in my case). I see that the tolerance is around 30% whoich means 100kohm on my slider in reality would output 70ohms.... Is there any way i can create a control circuit that would measure the actual resistance at the digopot, compare it with my input value and boost it to match that 100kohm? I am using a Pico 2.
What?? (30ppm != 30%)
Sorry if my terminology was wrong. This is what I was referring to.
So I basically want to divide the 1MOhm span into 256 sections and map it to a slider. Each position of the slider will correspond to the resistance of the ad5242 at that point.
Can you add some detail about what you are using the pot output for? Is it necessary for the absolute value of the resistance to be within a certain tolerance or simply the ratio of the output to 100% be correct?
Maybe a simple schematic diagram of the electronic circuit you are trying to create would help explain.
Rather than measure the resistance, it would be easier to measure the voltage you want to attain and adjust your pot setting to accomplish that.
+1. Bury us with details, it is quite likely that you can do what you want maybe in a way you had not yet considered.
a7
My project requires to create a module that will simulate resistances through code. the output will have two terminals, the Va and Vw. The user will use probes from these two terminals to connect it to his circuit to add resistances.
I hope I am clear thanks..
Yes, that helps. DigiPots may not be the solution you are looking for because they are designed more to provide a reasonably linear ratio of resistances rather than a predictable absolute resistance. Possibly with individual calibration one would fit your purpose.
That is to say they are potentiometers rather than rheostats.
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To answer your topic title question,
you would use your ohmmeter to measure the resistance across P0A, P0W, and P0B after programming the value into the pot.
thanks.. was looking if there's a visual ohmmeter of sorts that can be set up to be integrated as a control circuit to adjust the final output resistance
For example, if it would be okay to have the circuit disconnected from whatever you intend to use it with while you set the resistance then you could create a voltage divider composed of your DigiPot and a fixed resistor and adjust the pot setting until you got the voltage that the correct resistance would produce. You would measure this voltage with a microcontroller ADC. Then you could connect it to whatever needed it.
That seems like a clumsy way to do it and could probably be automated with relays or such to make it more friendly.
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