Circuit layout

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Del curso dictado por University of California San Diego

Internet of Things: Sensing and Actuation From Devices

88 calificaciones

University of California San Diego

Internet of Things: Sensing and Actuation From Devices

88 calificaciones

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.

De la lección

Stepper Motors

We are all basically made of motors, not really, but most robots are! When working with robotics, motors among several other things are some of the most important components you will chose for a project. In this lesson we will compare a variety of different motors widely used in DIY projects, especially DIY projects centered around robotics. We will take a deeper look at the stepper motor and what they are made of. We will then talk about the H-Bridge integrated circuit chip, why it is necessary for this projects and how it is used. Lastly, this lesson will guide you through the process of building a circuit capable of running a stepper motor. Schematics and code will be provided in order to gain a greater understanding of the stepper motor, as well as to facilitate the step by step instructions found in this lesson's documentation.

Introduction to Lesson 21:17

H-Bridge IC Chip1:43

Circuit layout3:42

Stepper sequence4:18

A look back at Lesson 20:51

Conoce a los instructores

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

Okay so we wanna take in even look at the age bridge by analyzing

the circuit layout or the pin out diagram of the age bridge.

So, we're gonna take what we just talk about,

and- >> Give a brief over view of what's going

on inside of the immigrated circuit of the age bridge.

>> Yeah.

So this is inside of what's going on.

You can see at the top you have power.

And what's happening here is you're gonna have the four transistors, and

they're kind creating that H, right?

And so, you'll have two of them closed and two of them open.

So you can only create a single path for a current to flow from DCC to ground.

And so when the current is going through the coil in one direction,

it's going to cause a specific direction and induce magnetic field.

Which will then make it cause the ferromagnetic material become north or

south on that side for the motor to be able to shift it.

Then, as you want to run the program, you'll then be able to actually change

which ones are open, and which ones are closed.

So that you can change the direction of current flow,

causing it to go from south to north to then move the motor into the next step.

Yeah so you can see as soon as though switches close,

that's when the path is created, and

the current can start to flow which will cause the field to be induced.

>> Yeah. >> Yeah.

So here we have the pin out diagram of the H-Bridge.

You can see that in the top right corner is your VCC so

it does need to be connected to a five volt power supply.

In the bottom left corner is VCC2.

That's gonna be the power.

That's the extra power needed to actually turn the motor.

So you do need at least 12 Volts on there otherwise your motor won't have enough

juice to be able to turn.

As well as that you notice that there are four set ups of the circuit.

So you have A1, A2, A3, And A4 and those are gonna be the transistors into h.

And then you have a large common ground in the center, so

those all need to be attached to ground.

Now for each of the circuits set ups, you have enables one and

two in the top left corner and enable three and four in the bottom right corner.

If those are turned off, the circuit will not be able to work.

And so you can actually use it so if you're using the GPIOs for something else,

you can have the enable turned off,

so that it won't actually run the current through the H bridge.

>> In our case, we actually have plenty of GPIOs for our particular projects.

So we're just gonna keep them enabled the whole time.

>> We're just gonna connect all the enables to the five volt power supply.

So that they'll just be on and we can run them through the ends there.

In which case the ends are coming in from the dragon board and

the outs go out to the motor.

>> Yeah, and

if you look kind of at this diagram a little more you see coil x and coil y.

That’s kind of going back to the other slide where you can see the two coils

there.

Those are in the center of the H.

Those are the exact same thing.

Those are the coils you see there as well.

So you can kind of relate it.

>> Yeah, and the thing is when you look at the left side, for the X,

you have to have one on and the other off.

They can't both be on at the same time, because looking at the H,

you only want the current to be able to flow one direction through the middle.

So you need one on and one off on both sides.

So that's where you put x and y, so you see that one is x and

the other is x not and then you've got a y and y not.

So it's the opposite.

>> Yeah, when we build the circuit you'll kind of get a better understanding of this

and you can always refer to the documentation if you need more help.

>> Yeah.

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