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Now we're gonna work with a potentiometer.

We're gonna wire together, wire it to the Arduino.

And we're gonna run a program.

That will blink a light, an LED on the Arduino and

blink it according to how much we've turned the potentiometer.

So what resistance we've measured across the potentiometer.

So, here are the components we're gonna use right here.

We got potentiometer right there, we got a knob, got three leads.

Got some wires right here.

Got our breadboard that we always use to wire things together, and

we got our Arduino over here.

And on the side,

I have my laptop which I will plug in the Arduino to give it power when we're ready.

So as a rule, we wanna start wiring without having any power plugged in.

Now, the program that will be running in the Arduino,

the name of that program is called Analog Input.

So if you look in your examples, if you start your IDE, go to examples.

Look in the subcategory number three called analog.

And then the program called Analog Input, that's the one we're using.

Now what that program does is it reads analog input on analog input A0.

So if we look at pin A0, let's take a pen or something.

A0 is that pin right there.

So it reads A0, reads the analog voltage, and

based on that voltage, it sets a light to blinking.

So an LED is connected on pin 13.

Now, this LED right here on the Arduino, it's already connected to pin 13.

So, what'll happen is that LED will blink.

And the rate that it blinks will correspond to the voltage that is

read at analog pin A0.

So what we're gonna do, is we're gonna take this potentiometer.

A potentiometer has three leads.

We're gonna take the top lead wire to power, five volts.

The bottom lead wire to ground.

Then the middle, we're going to take that, and run that straight into A0.

Now then what will happen is,

the voltage is read at A0 will depend on how we turn the knob.

It will be somewhere between five volts and zero volts.

And the voltage, if you look at the program it calls analog read.

It converts that voltage to a number from 0 to 1,023 and

that number will be used as the delay for the blinking.

So in fact if you look at this program, it looks very similar to the blink program.

The blink program had a delay of 1,000 milliseconds, so we're just gonna be able

to vary that based on how much we turn this potentiometer knob.

We could go from 0 to 1,023.

So 1,023 would be a little over a second, where 0 means just a constant.

Actually, I've already programmed to this Arduino.

So if you wanna do this yourself, just go get that program, it called Analog Input.

It's under examples, subcategory analog and

then the program's called Analog Input.

Program that into your Arduino, then wire it together.

So, start off, take the potentiometer.

We'll plug it into the breadboard.

It doesn't matter which three holes we plug it into but

notice the spacing of the these guys fits the spacing of the breadboard.

Oh, one thing to note, don't plug it in like this so

that all three pins are in the same row.

That wouldn't make any sense.

We want them to be in three different rows, so let's plug it in there.

Okay, so now we'll take the top connection of this, that's this one right here.

We'll plug it into power, get power from the board, five volt power, so

that's right here.

Okay, and then we'll take the bottom, plug it into ground.

Let's take that, that's the bottom lead of the potentiometer, plug it into a ground.

We've got a ground, here's ground, a couple grounds, yep.

And now we'll take the middle, which is the variable, and

we'll take that, use this green wire and plug it into A0, right there.

Okay, so that should be all we need.

Now, let us plug the Arduino into a USB for

power, see what happens.

Okay so, I hope you can see that.

You can see the LED is blinking at a rate, okay?

Now we should be able to change that rate by turning this knob, turn it.

Okay, that's faster, definitely faster, right?

Turn it some more.

That's definitely faster than before.

Turn it a little more.

There it is, almost solidly on at this point.

I can turn it back.

And that is it.

Thank you.

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Lecture 3.3 - Wiring Demo, Potentiometer

Arduino 接口

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