‫Welcome to the temperature sensor interface demonstration.
‫But the base is three board whose demonstration we're using two four did seven segment displays with
‫all the segments tied together through a 56 ohm resistor and all these are then fed into the j j b p
‫mod port.
‫We also have all the digits flex our control with two in thirty nine or four and transistors with the
‫470 ohm resistor connected to the base.
‫And these are fed into the J.
‫C. P. core of the basic three development board.
‫We also have the external temperature sensor now with the basic 3 board.
‫It does not support a single ended analog signal.
‫So you have to feed both the negative and the positive.
‫And also with the X ADC core on the actual Arctic's FPGA chip you can't feed it a 3.3 volt signal.
‫It can only handle a signal from 0 to 1 volt.
‫So what we do is we are dividing down the circuit the analog signal is reading takes in a three point
‫three volt signal.
‫So we have to reference our voltage to that 3.3 volt reference.
‫And so we have a voltage divider circuit which you can see is just consisted of three 2.2 ohm resistors.
‫Now these are 5 percent resistors not your 1 percent or point 1 percent tolerance resistors if you wanted
‫to have a super accurate temperature sensor.
‫You want to have a lot more accurate resistors but this just shows you the point that you can read a
‫temperature value off of this.
‫And as you can see we also have a slide switch 15 which is used to reset or are unable or our temperature
‫reading.
‫So if I pull that high it goes into a reset state where everything's at zero.
‫And our two other segments the one that indicates were negative or positive goes to an A and the one
‫that tells us if we're Celsius or Fahrenheit goes to an 8 because the micro blaze core we're using has
‫a default setting of setting everything to zero when it's in a reset.
‫So we pulled out of reset and now we can see we have a temperature of seventy nine point six five degrees
‫Fahrenheit.
‫So I can make that go higher by holding the temperature sensor.
‫If I put my fingers on there and hold it you'll see it jumps up there.
‫We just went up to 84 and you'll notice it doesn't jump up right away.
‫That's because we have a little delay built into the microbus processor where every half second we take
‫a reading and then update the measurement.
‫And that's just because your temperature typically doesn't jump around a whole lot.
‫It doesn't change super fast so a half second is more than fast enough for an update rate.
‫We also have our switch to zero which toggles between Fahrenheit and Celsius.
‫And currently we're in Fahrenheit which you can see by the denoted by the F we have on the end of our
‫display.
‫And if we pull that low the next time we update you'll see we're now twenty seven point eight four degrees
‫Celsius.
‫And if I toggle back up we'll go back to Fahrenheit.
‫So you can switch back and forth.
‫And this is just an example of the temperature sensor interface demonstration running on the basis three
‫development board.