‫Welcome to the potentiometer interface labs set up lecture we're going to show you how we set up for
‫the potentiometer interface lab.
‫If you're using an already or the RTC 7 where there is no 7st segment display located on the board you
‫will need to have the external 7st display on the breadboard over.
‫Or if you're using the bases three bases two or any other board that has a 7 segment display located
‫on it you won't have to worry about this portion of the setup.
‫And so what we have here is a 7 segment display.
‫We have the four different segments and they're all multiplex together.
‫So we have a total of 8 outputs that we're using.
‫We tie the decimal place output to too high which will make it so it doesn't show up.
‫And then the rest of them we tie through a 56 ohm resistor and take all of these outputs and feed them
‫back into our FPGA development board.
‫We also have since we're using four different digits we're using for two and thirty nine or four and
‫transistors with a 470 ohm resistor connected to the base of that transistor that we use to select the
‫different digits.
‫So in order to select a digit you'll want to turn that one the one segment you want to have it as a
‫one value of 1 which will select that segment and then the other three you'll give them a value of zero.
‫And so whatever value you then use by turning your individual segments on and off through these 56 some
‫resistors will then correspond to the value that shown up on the 7 segment display.
‫We also then have the potentiometer for a potentiometer.
‫We're actually you don't want to connect the one into the ground or your 0 volts the other and you'll
‫connect to your positive or 3.3 volts.
‫And it really doesn't matter.
‫You could switch these around.
‫You have you could take this positive and make it to the ground and take your other your ground and
‫make it to the positive.
‫Then you have the output which is important.
‫That needs to go.
‫That ties directly into your analog input on your FPGA development board.
‫And so as we turn the potentiometer we're going to vary the resistance value which will then vary the
‫amount of voltage we send back to the FPGA to then display our analog to digital reading on the 7st
‫display.
‫And so that is the lab set up for the potentiometer interface.