‫Welcome to the microphone interface on the basis three development board for this demonstration we have
‫the microphone breadboard breakout module from her just from out of fruit and we're taking the analog
‫signal output from the microphone and feeding in into the J x d c module on the basic 3 board.
‫Now with that microphone module we have to divide down the voltage because it gives us an output from
‫0 to approximately 3 3.3 volts or whatever Vcc is.
‫But the X ADC module a basic surfboard can only handle up to a 1 volt signal so we have to provide the
‫divided down.
‫And so what we're doing is we're taking and reading this microphone signal and when we see it we take
‫it and we're sampling it at 40 kilohertz because of the humans can hear up to 20 kilohertz.
‫And according to the Nyquist theory we want to sample at twice that.
‫So we sample it.
‫We take that value and we display it on the ladies.
‫So I want to put the microphone down and you'll notice as I'm talking you can see the different it light
‫up and they go as a talk a little bit louder the LDS go a little farther out or make certain noises
‫you can see that more and more Ltd's light up.
‫Now if I go and how my slide switch and set it to disable you notice that we just have the two Ltd's
‫in the very bottom right up and that's because one we don't have as precise a resistors as we need to
‫get this to be exactly correct we'd have to kind of tweak it but also the output of the microphone.
‫It has a DC bias to it.
‫So you take your Vcc and divide it by two.
‫So at approximately 1.6 5 volts are being fed out of this.
‫Currently right now when there's no sound whatsoever and then I just kind of gets amplified with our
‫with our voice.
‫And so as we talk you can see the different entities will light up and move of enabled again.
‫And as I talk over the microphone you can kind of just see the different entities.
‫They light up quickly in a little less and with lots of talk.
‫The harder I talk to our talk you see different melodies light up a little differently.
‫And so there is a demonstration of a microphone interface running on the bases three development board.