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‫Welcome to the potentiometer interface labs set up lecture we're going to show you how we set up for

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‫the potentiometer interface lab.

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‫If you're using an already or the RTC 7 where there is no 7st segment display located on the board you

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‫will need to have the external 7st display on the breadboard over.

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‫Or if you're using the bases three bases two or any other board that has a 7 segment display located

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‫on it you won't have to worry about this portion of the setup.

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‫And so what we have here is a 7 segment display.

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‫We have the four different segments and they're all multiplex together.

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‫So we have a total of 8 outputs that we're using.

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‫We tie the decimal place output to too high which will make it so it doesn't show up.

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‫And then the rest of them we tie through a 56 ohm resistor and take all of these outputs and feed them

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‫back into our FPGA development board.

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‫We also have since we're using four different digits we're using for two and thirty nine or four and

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‫transistors with a 470 ohm resistor connected to the base of that transistor that we use to select the

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‫different digits.

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‫So in order to select a digit you'll want to turn that one the one segment you want to have it as a

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‫one value of 1 which will select that segment and then the other three you'll give them a value of zero.

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‫And so whatever value you then use by turning your individual segments on and off through these 56 some

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‫resistors will then correspond to the value that shown up on the 7 segment display.

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‫We also then have the potentiometer for a potentiometer.

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‫We're actually you don't want to connect the one into the ground or your 0 volts the other and you'll

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‫connect to your positive or 3.3 volts.

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‫And it really doesn't matter.

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‫You could switch these around.

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‫You have you could take this positive and make it to the ground and take your other your ground and

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‫make it to the positive.

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‫Then you have the output which is important.

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‫That needs to go.

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‫That ties directly into your analog input on your FPGA development board.

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‫And so as we turn the potentiometer we're going to vary the resistance value which will then vary the

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‫amount of voltage we send back to the FPGA to then display our analog to digital reading on the 7st

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‫display.

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‫And so that is the lab set up for the potentiometer interface.