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‫Welcome to the potentiometer interface demonstration with the Arti board for the set up we have the

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‫Arti board which is connected to a four digit seven segment display.

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‫We are controlling each individual segment with the port J coming out of the p mod on the already and

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‫then we're doing the digits select through the port.

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‫J.B. Pieman can do the different digits select and we also have the potentiometer which is out here

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‫on its own but we're taking the output of the potentiometer and feeding it into the zero pen on the

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‫chip kit or Adreno headers on the Ardie board and with the lab to do is as we're changing the potentiometer

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‫as we move this we want to display the analog to digital converter reading on the 7 segment display.

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‫And we're going to be displaying this value in binary code decimal so it will be a decimal value we

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‫see with the the internal X A.D.C. on the Arctic's the chip located on the Ardie board is it.

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‫It uses a 12 bit Ayittey converter so the maximum value we can see is four thousand ninety six and the

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‫minimum value would be zero which is what's displayed right now being that the potentiometer is turned

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‫all the way to the left.

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‫Now if I go ahead and start rotating the potentiometer you'll see the value increment on the 7 segment

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‫display.

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‫So as I increase or decrease the resistance of this potentiometer you can see the HD reading changes

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‫and it keeps going up.

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‫We're at four hundred twenty three 450.

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‫Another thing to know.

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‫The very last digit the value that appears to constantly be an 8.

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‫This is because we're sampling at such a high rate we're currently sampling it approximately two hundred

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‫thousand samples per second.

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‫And so that last digit is going to constantly change it's probably anywhere from zero all the way up

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‫to 9.

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‫And so that's why it appears to be an eight.

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‫All the segments appear to be valid because we're constantly sampling so says it's changing so fast

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‫it appears to be stuck 8.

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‫If you'd have it so you can stop the sampling.

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‫Then you would see that you'd have a different value other than eight.

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‫But in order to continue the display as we rotate the Pentium we have to be in a continuous sample mode.

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‫So if we keep going.

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‫We'll see if we go all the way to the right.

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‫We should get up to 4000.

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‫Now what we'll know is we can't quite reach 4000 Exactly.

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‫And if I go all right you can see we get to three thousand nine hundred eighty eight.

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‫And the reason we can't get to the 4000 96 is because there are several things going on.

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‫If you look in the schematic of the Arti you'll see that there are several resistors and a capacitor

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‫there that's feeding in the positive and negative of the analog signal and due to that we're losing

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‫some voltage.

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‫So we're not able to feed directly 3.3 volts into the ADC.

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‫And so if I go all the way back to the left you'll notice that the value starts to decrease the 80s

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‫eight to de-value and I can go all the way back to the left and get it back down to zero.

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‫And that is so that's telling us that the potentiometers all the way to the left wing.

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‫All the right end get almost up to 4000.

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‫And so this is just to show you that you can read analog signals on your FPGA board using the X DC internal

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‫IP core and so that is the potentiometer interface demonstration with the keyboard.