Lecture 1.3 - Raspberry Pi vs. Arduino

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From the course by University of California, Irvine

The Raspberry Pi Platform and Python Programming for the Raspberry Pi

1394 ratings

University of California, Irvine

The Raspberry Pi Platform and Python Programming for the Raspberry Pi

1394 ratings

Course 4 of 6 in the Specialization An Introduction to Programming the Internet of Things (IOT)

The Raspberry Pi is a small, affordable single-board computer that you will use to design and develop fun and practical IoT devices while learning programming and computer hardware. In addition, you will learn how to set up up the Raspberry Pi environment, get a Linux operating system running, and write and execute some basic Python code on the Raspberry Pi. You will also learn how to use Python-based IDE (integrated development environments) for the Raspberry Pi and how to trace and debug Python code on the device. Please note that this course does not include discussion forums.

From the lesson

Module 1

This module describes the basic functionality the Raspberry Pi B+ board. I'll describe how to set up the board, configure it, and use it. An important point differentiating Raspberry Pi from the Arduino platform which we have talked about previously is that Raspberry Pi uses an operating system. I'll describe some of the implications of an operating system on the behavior of the Raspberry Pi as an IoT device.

Lecture 1.1 - Raspberry Pi Board6:42

Lecture 1.2 - Raspberry Pi Processor5:45

Lecture 1.3 - Raspberry Pi vs. Arduino8:34

Meet the Instructors

Ian Harris
Professor
Department of Computer Science

[MUSIC]

So in this specialization we spent a lot up until this point talking about Arduino

and its capabilities and how to use it.

And now we're moving on to Raspberry Pi, take a look at that.

So let us compare the two and see how they differ.

And a lot of people think that when you look at a processor or

board you say look this one is just faster and better and

superior I should use that, forget the old one.

No, no, no, no, Arduino is older, but Arduino is really well suited to certain

tasks, so really I wouldn't say Raspberry Pi's superior to Arduino or

Arduino's superior to Raspberry Pi.

It just depends upon what you want.

They're each a different fit for what you need.

Okay, so let's start off.

Raspberry Pi processor is faster.

It's 900 megahertz versus 16 megahertz on the Ardiuno, so that's one advantage.

It's a 32-bit processor versus 8-bit.

So Raspberry Pi is 32-bit, Arduino's 8-bit.

And if you remember, what we mean by 32-bit, 8-bit,

when you say a processor is 32-bits, that means that the number that it stores

inside that it works with those are 32-bits, for the most part.

Now you can use smaller or bigger, but the hardware is built for 32-bit.

So if you look at the adder inside, it'll add two 32-bit numbers, right?

Or if you have a register that stores data, you'll store a 32-bit number, so on.

So, you have 32-bit versus 8-bit, which generally means that the Raspberry Pi

can have a lot more resolution, a lot more accuracy than the Arduino, okay?

And it can do 32-bit operations rather than 8-bit operations,

so at some level it can do things faster,

cuz it can do things more in bulk if you're clever about how you code it.

So, also you can support a much bigger address space,

if you have 32-bits for the address space, 2 to the 32 is 2 gig?

[LAUGH] I'm slow with my math today.

But that determines the size of the address space.

So, Raspberry Pi can support a much bigger address space.

So Raspberry Pi has more memory.

And by memory, there are different types of memory, right?

But in all cases Raspberry Pi has more.

So, if you look at the Arduino it has 32 kilobytes of flash,

whereas Raspberry Pi has 512 kilobytes of flash.

I'm sorry, change that around, Raspberry Pi has 4 gigabytes of flash,

where Arduino only has 32 kilobytes of flash.

If we look at SRAM, the RAM, there's 2K of RAM in an Arduino,

where there's 512K of RAM inside a Raspberry Pi.

1K of EEPROM [COUGH] inside an Arduino, and

actually I'm not sure what the comparable number is in Raspberry Pi.

But, I'm sure it's much bigger.

Also, the Raspberry Pi has a microSD slot, not to mention the USB slots, right?

So if you want to you can extend its memory by having a bigger microSD,

which is an extra flash that you can just plug in and it's built in.

Arduino sure you can get a shield and have SD slot or something like that, but

it's all built into with Raspberry Pi.

So Raspberry Pi has a lot more memory.

Raspberry Pi has lower input/output voltage levels.

So Arduino, its input/output voltage levels are five volts,

zero to five volts, right?

Low is zero volts, high is five volts.

Raspberry Pi is 3.3 volts higher, 0 to 3.3.

Now what difference does that make?

That means that the Raspberry Pi is generally going to consume or

could consume less power.

Let's put it like this, a big factor in power is a voltage.

In fact the power goes with the square of the voltage right?

So the voltage is the big power consumption issue.

So by reducing the power level, you're reducing the power.

Now on the other hand, Raspberry Pi also is going to consume a lot consume more

power because it runs so much faster, it has so much at a higher clock frequency.

So that probably more than likely offsets the power consumption issue.

But going to 3.3 volts is an attempt to reduce power.

So that needs to be kept in mind.

So with the Raspberry Pi when you interface,

this will come up later at the end of this module, but also in the next module.

When you interface a Raspberry Pi with different components, you gotta make sure

that those components are expecting 3.3 volts and not 5 volts, right?

And you don't want the external component to drive onto Raspberry PI's

pins with 5 volts when Raspberry PI is expecting 3.3.

So that can become an issue and we'll deal with that later.

Okay, so a big sorta obvious difference from a user between a Raspberry Pi and

Arduino is that the Raspberry Pi runs an operating system and the Arduino does not.

Now, actually this came from an old slide, I'll just go over it again.

So what is an operating system, just to summarize really quickly.

Now, we all have a knowledge of what an operating system is, right?

People have used Linux, and Windows, and Mac OS X,

and Android, these are all operating systems.

But what an operating system essentially is,

it's a layer of software that runs on the hardware.

So if you look at the picture on the left side,

you've got application on top of microcontroller.

That's what we did with the Arduino.

We wrote our application, wrote the code ourselves, and then that ran directly on

the microcontroller, so you compile it and that's what runs.

So what the processor is running is exactly what you wrote, and that's it.

On the other hand, the other picture there on the right side,

it shows the application at the top that maybe you wrote.

At the bottom there is a microcontroller that it has to essentially run on,

but there's all this software in between.

That whole block we'll call, that's a simplified version of an operating system.

This is a simplified version, we can't go into operating system class but

this is the idea.

There are library functions inside there that the application can call.

And we had library functions with the Arduino too,

but these library function are a part of the operating system.

And these library functions make system calls which are other

parts of the operating system and

those system calls are what actually interact with the microcontroller.

So the application doesn't directly interact with the microcontroller.

So what that means is the application can't directly change a pin,

turn a pin from high to low or low to high, right?

Because it's gotta go through the operating system.

It basically makes a request, and then operating system library function and

the operating system might be function decides that request is okay and

then serves the request by switching the pin if it feels like it should.

So, this is extra layer of software in there, the operating system is running.

So, when you run your application, it's not just your application,

your application It's calling the operating system and

the operating system is doing the dirty work of dealing with the hardware.

Okay, so there's this layer of software, that's an operating system.

And that is enabled in a Raspberry Pi.

A Raspberry Pi you use an operating system where an Arduino you don't.

And this is not to say no one has ever thought of an operating system for

Arduino, probably somebody has, but no, either not in common use.

And it's hard to imagine that you could do it, given the constraints.

So that fact that you have this extra layer of code, this operating system code

that requires processing power, that slows everything down.

Your application can't just switch an LED off and on, right?

It's gotta call the operating system code which then does it, right?

So there's this slow down because you're running an operating system.

Also operating systems use a ton of memory.

So suddenly you need lots of memory on your machine just

because the of the operating system.

Even if your application doesn't require hardly any memory.

Even if all your application's doing is turning an LED off and on.

You still need tons of memory just for the operating system, right?

So a regular Arduino can't sustain that, but a Raspberry Pi can.

So, Raspberry Pi,

that's sorta the main obvious difference from the user, is that on Raspberry Pi

you're working with an operating system whereas with Arduino, you really are not.

You just write your code and it runs directly on the microcontroller.

Now operating systems, they slow things down, they have lots of issues, but

they have lots of advantages.

And we will get into that over the courses of specialization really.

Into this module and into the next, we'll talk about the advantages and

the benefits you get from using an operating system on a Raspberry Pi.

Thank you.

[MUSIC]

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