Arduino Uno Board Overview

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Welcome to tutorial 3: Arduino board overview! This time, we’re going to talk a little bit about the hardware on the board itself and we’ll be using the Arduino Uno. Figure 1 shows an Arduino Uno board made by Arduino in Italy. This board is an authentic board, and Arduino is an open source platform.

Figure 1: a genuine Arduino Uno board.

Open source means that all the design files, schematic files and software for the Arduino are available to the public and open, and people are allowed to copy them. And a lot of people have copied them.

Buying Your Arduino

There are a lot of Arduino clones and derivatives available for purchase, and many of them are okay and just as good as the Arduino version, but I’m going to suggest for the purpose of following along and to be sure that we are all on the same page that you buy a genuine Arduino Uno.

You can grab one from Arduino.cc or grab one on Amazon (and maybe save a few bucks).

There are two different types of Arduino Uno boards. We have the one from figure 1 and there is also a surface mount board, which we can see in figure 2.

Figure 2: Arduino Uno SMD version.

They’re almost the same thing except that the ATMega328p chip is a surface mount chip instead of a dual inline package or DIP chip.

I suggest you go with the DIP or dual inline package board, especially if you’re a beginner.

Here’s the reason: if you’re new to Arduino there is a chance that you may fry the CPU on the board. If that happens with the SMD edition, you’re most likely going to have to buy a whole new board unless you’re really good at surface mount soldering and have the proper equipment and skills. If you accidentally kill the chip on the DIP version, you can just replace the chip instead of buying a whole new board or worrying about soldering.

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There are ATMega328p microcontrollers available that come pre-loaded with the boot loader. You can get those for a couple of dollars each versus twenty-something dollars for a new board. In fact, I suggest you keep a few spares on hand just in case.

Arduino Board Hardware Overview

Now, this is a basic Arduino board overview, so we’re not going to cover every single component on the board. We’re going to go over some of the main features and then take a closer look at some of the hardware a little bit later in another article.

For the following discussion refer to figure 3.

Let’s start with the digital pin headers up top. These give access to the pins on the microcontroller; they’re either inputs or outputs and you’ll notice that some of the digital pins (0 through 13) have a little tilde (~) mark next to them. These are the PWM or pulse with modulation pins, which, as you may guess, are PWM capable.

Figure 3: important parts of the Arduino Uno.

You’ll also notice pins zero and one have a TX and RX next to them. TX stands for transmit and RX stands for receive. These pins are used for talking to the PC or other devices. You’ll also notice that there are two TX and RX LEDs on the board (left of the Arduino logo in figure 3). The LEDs will blink when the Arduino is transmitting or receiving information.

This can come in handy for troubleshooting. If they’re blinking, you know the Arduino is communicating with the PC or whatever it’s supposed to communicate with. If they’re not, then something is probably wrong.

Next, we have the analog pin headers at the bottom right — A0 through A5. These connect to the analog to digital converter (ADC) pins on the Arduino’s microcontroller.

For example, if you want to read the temperature of something, you can take a thermistor (temperature sensitive resistor), plug it into the holes you see there and use that to translate the analog temperature reading into a digital value the microcontroller can understand and work with. You can also use the analog pins just like the digital pins.

Next to the analog pins we have power pin headers and ground. We have two grounds and we have a 3.3 V and a 5 V pin. If you hook a wire up to the 5 V or the 3.3 V header socket and measure it with a volt meter, you’ll get either 5 V or 3.3 V. You’ll probably use 5 V more often than 3.3 V.

A quick word on the ground pins is in order. Ground is essential, it’s the lowest voltage on the board, usually zero volts. You’ll need the ground with pretty much everything you do if you’re connecting anything to your Arduino.

On the lower left we have a black DC power jack. This is useful if you need to power the board from an external battery of some sort.

In the upper left we have a reset button (R3 boards) and this reset button may be located more towards the middle directly above the microcontroller (as in figure 3) depending on the revision of the board you have. But it looks the same, so it’s not hard to find.

The reset button starts over at the beginning of a program. It doesn’t erase your program. It just starts over again if you run into a problem. There is also a reset header next to the 3.3 V pin which does the same thing. When a low (0 V) is applied to that header, it’ll reset the board.

I hope you enjoyed this Arduino board overview. For now, that’s all the detail we’ll need to get started. What will create with your Arduino?