Operational Amplifiers

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From the course by University of California San Diego

Internet of Things: Sensing and Actuation From Devices

87 ratings

University of California San Diego

Internet of Things: Sensing and Actuation From Devices

87 ratings

Have you wondered how information from physical devices in the real world gets communicated to Smartphone processors? Do you want to make informed design decisions about sampling frequencies and bit-width requirements for various kinds of sensors? Do you want to gain expertise to affect the real world with actuators such as stepper motors, LEDs and generate notifications? In this course, you will learn to interface common sensors and actuators to the DragonBoard™ 410c hardware. You will then develop software to acquire sensory data, process the data and actuate stepper motors, LEDs, etc. for use in mobile-enabled products. Along the way, you’ll learn to apply both analog-to-digital and digital-to-analog conversion concepts. Learning Goals: After completing this course, you will be able to: 1. Estimate sampling frequency and bit-width required for different sensors. 2. Program GPIOs (general purpose input/output pins) to enable communication between the DragonBoard 410c and common sensors. 3. Write data acquisition code for sensors such as passive and active infrared (IR) sensors, microphones, cameras, GPS, accelerometers, ultrasonic sensors, etc. 4. Write applications that process sensor data and take specific actions, such as stepper motors, LED matrices for digital signage and gaming, etc.

From the lesson

Terminology/Cheat Sheet (Beginner)

In this course, you will see a lot of new words and acronyms you might not be familiar with. If you feel comfortable with your knowledge of tech terminology, feel free to skip these lessons since they will not affect the overall integrity of the course. If you see something that you want to know a little more about, feel free to watch the video to gain insight on some basic concepts. We do expect you to know the majority of this material before going into the next module, we would recommend going through the lessons as a quick brush up.

Introduction to Lesson 22:01

Electromagnetic Spectrum2:05

Operational Amplifiers3:27

A look back at Lesson 21:03

Meet the Instructors

Ganz Chockalingam
Principal Engineer
Qualcomm Institute of Calit2, UC, San Diego
Harinath Garudadri
Associate Research Scientist
Qualcomm Institute of Calit2, UC, San Diego

Operational amplifiers otherwise known as opamps are what amplifiers are made of.

So I would say "Hey, make an amplifier." What are you going to make it with?

You're going to make it with an opamp.

The device.

The opamp device.

>> Let's just go over what an amplifier does and basically it just takes

a voltage signal and increases it >> Say you have for example a 1.5 volt

power source but you need say 3 volts to power an LED or something like that.

You just use the amplifier to amplify that 1.5 volts to 3 volt signal.

>> Yeah and we will be doing this in this course

to amplify the signal of our GPIOs on the expansion header.

So now when we reach that module, I believe it's module three,

to build our amplifier, we are going to go a lot more in depth for now.

You can kind of take a look here at some of the key characteristics of, you know,

the operational amplifier.

Maybe do a little research of your own, check it out.

Check out the Wiki, look at our document.

>> Yeah, it'll help you to familiarize yourself with this stuff right now so

later on you might not be confused when we talk about it more in depth.

>> Yeah, we're actually gonna solve the ideal amplifier equation for you later.

But like Randy just said, we wanna kind of just give you a little insight.

So, let's take a look at what we're actually gonna maybe do later.

All right, there we go.

The NTE987 is the op amp that we are going to be using for this course.

It is special because if you look right there on the screen you have the chip

that we're using.

Took a picture of that.

To the right of it is the diagram for an amplifier.

Now That's non-ideal.

And it takes two voltage inputs as your rail.

So that's what you're stepping it up to.

For instance, for us, we step ours up

from 1.8 to, I think, somewhere around 3.3.

Now, in order to do that, you would need a positive rail and

a negative rail, that's the traditional operational amplifier.

But for us we chose a special chip.

This chip, the NTE, actually only requires a positive rail which means

you can create an amplifier Just by using the pins on your board.

And you can step it up to the five volt, you can step it up to the 12 volt,

which is your system DCN pin on there,

which we're going to go over later and everything.

But that's the great part about this.

You don't need to go buy some expensive power supply

to get yourself a positive and a negative voltage.

You don't need to build yourself a virtual ground,

even though I would recommend checking that out online.

It's a very cool concept [LAUGH] on turning

a positive voltage into a virtual negative voltage kind of deal.

But yeah, so you see up there you have the NTE 987 operational amplifier chip.

It has four amps in it, we're gonna go over all this again, but just thought kind

of show you some cool little pictures of the amplifiers we built along with

the diagram for the NTE, get you familiar, get your feet wet, look up a little more.

>> Right.

>> Take the keywords that we've kind of talked about check out the documentation

and we will see you later.

Alright.

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