A Beginner’s Guide to Microcontrollers

What do remote controllers, routers, and robots all have in common? Microcontrollers! These days, beginner-friendly microcontrollers are easy to build with and program using just a laptop, a USB cable, and some (free) open-source software. The catch? There are like, 4324302* different microcontrollers and it can be daunting to get started, especially if you’re just getting into electronics. Where the heck do you start?!

Right here, bbies, I got chu. Whether you are looking to build some cool electronic projects, learn programming/tech, or wanting to teach others about electronics, this tutorial will help you figure out what microcontroller is right for your needs, goals, and budgets. Yay! Let’s get started!

Read Time: ~ 20 min

*Ok, ok, maybe not *that* many, but definitely a few dozen!

 

Wait…What is a microcontroller??

Maybe you’ve seen this word and were like “uhhh..?” but didn’t feel comfy enough to ask*. Totally fine, here’s a quick rundown:

A microcontroller is a “simple computer” that runs one program in a loop. They are designed to perform a single, specific task.

In this guide, we’ll be focusing on microcontrollers that have breakout boards, or a board that makes it easier to connect to and program the microcontroller.

On a breakout board, the microcontroller pins are soldered to a printed circuit board (“PCB”), headers or other connectors are added to the PCB, and some basic firmware, or permanent software, is loaded to prep the microcontroller to receive signals.

*Questions are always good even if they are “dumb” or “n00by”, just find a safe space — like this site or Instructables!

What’s the Difference Between the Raspberry Pi and a Microcontroller?

The Raspberry Pi is not only small and adorable, it is also a full-fledged computer! 😀

Computers have microprocessors AND microcontrollers that work together to perform many tasks at once.

The microprocessor is what does the “heavy lifting” in a computer. It performs the instructions and calculations that make the computer work. Microprocessors are much faster than microcontrollers, but they need external resources like RAM, Input/Output ports, etc., whereas a microcontroller is typically self-contained.

Computers (which are microprocessors) can run multiple programs at a time — you can surf the Internet, reminisce with old photos, write a paper, and have like 1000 tabs open all at the same time! Microcontrollers… not so much. You can do one of those things, but not all.

To learn more about the Raspberry Pi, check out the last section of this tutorial!

Arduino (Uno)

A robust, open-source microcontroller and programming environment designed for beginners with some knowledge of circuits.

Recommended Ages: 12+ (or kids comfy with programming and algebra)

Difficulty: Intermediate

Average Cost: ~$35

There are lots of different types of Arduino boards. This is the Arduino Uno, the best fit for beginners! There are boards that are larger, smaller, wearable, and for specialty use cases like robotics.

Being familiar with Arduino boards and programming maps well to projects and careers in computer science, engineering, and design.

Hardware Features

  • The Arduino Uno has 14 Digital Input & Output (“I/O”) pins, 6 Analog I/O pins, 2 Power Out pins (3.3V and 5V), and 3 Ground (GND) pins.
  • Power input can be anywhere from 5 to 12 VDC
  • The ICSP header (right side in both photos) allows you to connect a ton of different add-on boards called “shields”.
    • For example, you can add a WiFi shield to connect your Arduino to the ‘net!

Example Project: 

Robot Mini Golf Obstacles

Motion-Reactive Shake the Maze Game!

Purchase/Learn More: Arduino Website (www.Arduino.cc)

Micro:Bit

A friendly lil’ microcontroller handy for kids and folks just getting started with coding and hardware.

Recommended Ages: 8+ (or kids comfy with circuits and simple tools)

Difficulty: Beginner

Average Cost: ~$15

The Micro:Bit is a great tool to start learning how to code, teaching others, particularly elementary school students, how to code, and making simple and quick electronic prototypes.

The Micro:Bit is a collaboration between Microsoft and the BBC to bring educational computers into classrooms around the world.

Hardware Features:

  • The Micro:Bit has 3 Digital and Analog I/O pins, 1 Power Out pin (3.3V), and 1 Ground (GND) pin
  • Power input should be 3 – 5 VDC via micro USB cable or battery pack connector.
  • It also has lots of onboard inputs, outputs, and sensors!
    • 5×5 (25) LED matrix
    • Two (2) Pushbuttons (A, B)
    • Radio Transmitter and Receiver
    • Accelerometer
    • Compass
    • Light and Temperature Sensors
  • For more I/O pins, grab a Micro:Bit breakout!

Example Project: 

Text Messenger Puppet!

Purchase/Learn MoreMicro:Bit Website

Circuit Playground Express

A versatile microcontroller great for kids and folks just getting started with coding and hardware.

Note: There is also the Circuit Playground Classic — the hardware is nearly identical, but this board is programmed in the Arduino IDE.

Recommended Ages: 8+ (or kids comfy with circuits and simple tools)

Difficulty: Beginner

Average Cost: ~$25

The Circuit Playground Express, or CPX, is a helpful tool to learn how to code, teach others how to code, and make quick prototypes for beginners to experts alike.

The Circuit Playground Express is a powerful and versatile microcontroller created by Adafruit Industries.

Hardware Features

  • The CPX has 7 Digital/Analog Input & Output (“I/O”) rings that are also capacitive touch!
    • 1 “true” Analog I/O ring
    • 2 Power out ring (3.3V)
    • 3 Ground (GND) pins
  • Power input should be 3 – 5 VDC via micro USB cable or battery pack connector.
  • There are also tons of onboard inputs, outputs, and sensors!
    • 10 Mini Neopixels (can be all colors)
    • 2 Pushbuttons (A, B)
    • 1 Slide Switch
    • Infrared Transmitter and Receiver
      • Can receive/transmit remote control codes, send message between CPXs, and act as a distance sensor
    • Accelerometer
    • Sound sensor and mini speaker
    • Light and Temperature Sensors

Example Project:

 Minecraft Gesture Controller!

Purchase/Learn More: Adafruit Industries

Makey Makey

An interactive introductory microcontroller great for young kids and folks new to electronics and coding, especially for those who want to play with technology without having to build circuits and code.

Recommended Ages: 5+ (or kids comfy with simple tools)

Difficulty: Beginner

Average Cost: ~$50

The Makey Makey is a great first step into electronics and technology — no programming required! Connect alligator clips to the pads and then connect any somewhat conductive material, like hands, fruit, or metal objects, to trigger certain keyboard and mouse keys.

The Makey Makey is an Arduino-compatible board, meaning that you can also reprogram it using the Arduino Integrated Development Environment (“IDE”).

Hardware Features

  • The Makey Makey has six (6) capacitive touch pads on the front of the board:
    • Four control the keyboard arrow keys,
    • One controls the spacebar, and
    • One controls the left mouse click.
  • On the back of the board are header pins for more controls (also capacitive touch):
    • Six (6) pins that map to letters,
    • Four (4) pins that map to arrows,
    • Two (2) pins that map to mouse keys, and
    • One (1) pin that maps to the spacebar key.
    • There are also three (3) general I/O pins, a 5V power pin, and a ground pin.

Example Projects

Beginner: Floor Piano

Intermediate: Interactive Survey Game!

Purchase/Learn More: Makey Makey website

Other Common Boards

There are waaaay too many microcontrollers to cover in one tutorial. If you have a super specific specialty need, there is probably a microcontroller for that (just like apps!). To get a feel for some of the other boards not mentioned in this tutorial, peruse the inventories of SparkFun Electronics and Adafruit Industries and/or ask folks in the field!

Here are a few of my favs:

Particle Photon

Similar to the Arduino Nano, the Photon is a WiFi connected microcontroller that can be programmed wirelessly. The easiest setup uses a (free) smartphone app, but if can also be programmed directly via USB in almost the same language as Arduino*.

Recommended Ages: 12+ (or kids comfy w/ circuits and coding)

Difficulty: Intermediate

Cost: ~$20

For more info and to get the Photon setup, visit the Particle online store here.

Example Project

IoT Industrial Scale

*Wiring is the code framework, so most Arduino code will work without modifications. Can also write in C/C++ or ARM assembly

Adafruit HUZZAH ESP8266 Breakout

A super small, super cheap (and currently very popular in the IoT* community) WiFi microcontroller. You’ll need an FTDI or console cable. You can use the Arduino IDE to program this board or NodeMCU’s Lua Interpreter.

Recommended Ages: 14+ (or kids comfy w/ hardware & software)

Difficulty: Intermediate++

Cost: ~$10

For more info, visit the HUZZAH Adafruit product page.

(SparkFun also has a similar board, the “ESP8266 Thing”, which you can find here for ~$15.)

*IoT stands for “Internet of Things”, which is the term that refers to connecting and controlling various hardware devices, like sensors and household electronics, to the Internet.

Adafruit Trinket M0

A teeny tiny yet powerful microcontroller that blurs the lines between computer and microcontroller (it has an ATSAMD21E18 32-bit Cortex M0 processor). It can be programmed with Circuit Python or in the Arudino IDE.

Recommended Ages: 14+ (or kids comfy w/ hardware & software)

Difficulty: Intermediate

Cost: ~$9

For more info, visit the Adafruit product page for the Trinket M0.

There are a TON of other M0 boards, similar in scope to the Arduino Zero connectable microcontrollers. If this doesn’t suit your needs or your fancy, search around on the Adafruit and SparkFun websites!

Wearable Microcontrollers

There are also a handful of microcontrollers designed for wearable projects!

What makes these special is that they can be washed, so you don’t have to rip them out of the awesome project you made (but do remove the battery!).

Wearable microcontrollers also have special I/O pins that make it easier to sew into clothing and stitch circuits with conductive thread. Here are a few of my favs:

Adafruit FLORA

A circular sewable microcontroller with 14 inputs and outputs. Can be washed (but def remove the battery).

Recommended Ages: 12+ (or kids comfy w/ circuits and coding)

Difficulty: Intermediate

Cost: $15

For more information, visit the Adafruit FLORA product page.

Arduino Gemma

A lil’ tiny sewable microcontroller with 3 inputs and outputs. Perfect for hiding, connecting to small objects, and creating jewelry.

Recommended Ages: 12+

Difficulty: Intermediate

Cost: ~$5

For more information, visit the Arduino Gemma product page.

Arduino Lilypad

A circular sewable microcontroller with 14 available inputs and outputs.

Recommended Ages: 12+

Difficulty: Intermediate

Cost: ~$25

For more information, visit the SparkFun product page for the Lilypad.

 

Raspberry Pi 3

The Raspberry Pi, or Pi for short, is a credit-card sized computer* that runs a special version of Linux and can be programmed to control hardware.

Recommended Ages: 12+
Or kids comfy with coding and algebra

Difficulty: Intermediate (easy as a computer)

Average Cost: ~$35

The Raspberry Pi computer, or Pi for short, can be used as a “standard” computer or as a controller for all sorts of hardware projects. It is a great first computer for kids to use and learn to code on, and is widely used by hardware experts to build all sorts of electronic projects, from robots to 3D printers to home automation systems!

The Raspberry Pi has changed the way we build electronics! There are a few different versions, the most recent is the Raspberry Pi 3 and the Pi Zero, a miniature version of the Pi 3 for just $10.

Hardware Overview

  • The recommended Operating System (“OS”) is a special version of Linux called Raspbian.
  • The Pi has 40 General Purpose Input and Output (“GPIO”) pins.
    • 26 Digital I/O pins (no Analog I/O)
    • 4 Power Out pins (two 3.3V and two 5V)
    • 8 Ground (GND) pins
    • 2 Specialty Pins (I2C ID EEPROM, advanced use only)
  • The Pi also has most standard computer features:
    • 4 USB Ports
    • 1 Ethernet port
    • 1 HDMI port
    • 1 Audio Jack
    • 1 Camera Module Port

Example Projects

Local Cloud Server

IoT Pet Monitor! (Raspberry Pi Zero)

Impact Force Monitor

Purchase/More InfoRaspberry Pi Foundation

*The Pi can be used similar to a standard microcontroller AND can also control microcontrollers! Basically, the Pi is super awesome and I *have* to include it even tho it is technically a computer 🙂

Final Thoughts

If you are just getting started and want to build all sorts of projects, I’d recommend the Circuit Playground Express. It’s super easy to get up and running and has a ton of onboard gadgets.

If you are super interested in computer networking, AI, or connecting things to the Internet (e.g. making a “Smart Home”), I’d suggest the Raspberry Pi.

If you want a sturdy, stable, and reliable board to build a wide variety of projects, go with an Arduino.

If you still have no idea where to start and are totally intimidated, start with the Micro:Bit — it’s only $15 and has plenty of snazzy things on it to play with. Plus, if you get one for your friend, you can send lil’ messages back and forth 🙂

The best advice I can give you is to find a project you are passionate about and build it! There are tons of tutorials online so search around for someone who has built the same or similar project. Build off of their findings and adjust as you please!

And of course, leave any related questions in the comments and I’ll do my best to help!

Happy hacking!

Intro to the (Headless) Raspberry Pi!

Finally! Use your Raspberry Pi without spending what feels like forever connecting external peripherals and dealing w/ a cable monstrosity: Configure your Pi to be headless! (not the scary kind tho) This is particularly helpful for folks teaching workshops with the Raspberry Pi, since it can be cumbersome (and expensive) to provide monitors, keyboards, and mice for every student.

I’m assuming that y’all know a bit about the Pi, so this tutorial will not cover what the Pi is or it’s awesome capabilities (I’m lookin’ at you, GPIO pins!). To learn more about what the Pi can do, check out some of my other tutorials (see the last section in this tutorial) or leave a comment.

What is covered in this tutorial: Enabling and using SSH, a general overview of the Linux terminal window, and how to connect to the Pi’s GUI (Graphical User Interface, aka the Desktop view) via SSH.

Read Time: 15 min

Build Time: ~20 min

Cost: Free! (assuming you already have an RPi and Ethernet cable)

Materials

Computer with Ethernet port & SD Card slot

– Raspberry Pi 3

– SD Card (8GB or larger)

– MicroUSB to USB power cord

– Ethernet Cable

– RecommendedRaspberry Pi Case & GPIO cable

Software

For this project, you’ll need the following (free!) software programs:

 

Configure the SD Card

1. Download your favorite flavor of Raspbian! You can get the most recent version here.

2. Insert your SD card and open Etcher.

3. Select the Raspbian zip file, the driver for your SD card, and click “format”.

4. Enable SSH access

Open the file contents for the SD card. Add a new text file titled “SSH”. If the computer adds a file extension (e.g. “.txt”), delete it and ignore any warnings.

5. Eject the SD card and insert it into your Pi.

 

Let’s Get Connected!

1. Plug in the Ethernet cable between the Raspberry Pi & your computer.

2. Plug in the USB power cable.

Check that the red power light turns on and that the Ethernet port lights (yellow & green) are on and/or blinking.

3. Connect the RPi to the World Wide Web (aka the Internet).

Go to Settings -> Network & Internet -> Change Adapter Options (aka Network Connections).

Click on the Ethernet connection, hold down “CTRL”, and then click on your WiFi connection.* Right-click in the window and select “Bridge Connections” — this will bridge the connection between the Ethernet port to your WiFi port.

*If you select the WiFi connection first, it will bridge the connection from the WiFi to the Ethernet, which would allow you to log into the Pi but not connect to the Internet.

4. Open PuTTY and log in to the Pi using the “raspberrypi.local” IP address.

Default username: pi

Default password: raspberry

5. Change the default password by typing passwd and following the prompts.

 

Navigating the Linux Terminal Window (Shell)

The terminal window is the control panel for the system.

It typically shows a command prompt, which gives us information but is not part of the commands to the system. Most commonly the command prompt displays the user’s login name and the current working directory (represented by a twiddle: ~ ).

Inputting Commands

Commands are written after the prompt and inputted by pressing the Enter key.

Commands can be issued as-is or followed by one or more options. Options usually have a dash in front of them, like the following:

ls -a

You can view the options for a specific command by typing the command name followed by “–help” (will cover this more later).

 

 

 

 

 

 

 

 

Linux Hot Keys!

There are a handful of special key combinations that make navigating the terminal window easier and faster. Here are a some of the most common ones:

  • Ctrl+A – Move cursor to beginning of command line
  • Ctrl+E – Move cursor to end of command line
  • Ctrl+C – End running program
  • Ctrl+D – Logout of current session
  • Ctrl+R – Search command history
  • Ctrl+Z – Suspend a program

 

  • Left and Right arrow keys – Move cursor one place to the left or right on command line
  • Up and Down arrow keys – Browse command history
  • Shift+PageUp and Shift+PageDown – Browse terminal buffer (to see text that is off screen)
  • Tab – Command or filename completion
  • Tab Tab – Shows file or command completion options

Practice using these every time you are in the terminal window and you’ll quickly become a Linux wizard!

Getting Help in the Terminal

1. Manual and Information Pages

The manual pages are an exhaustive resource for all of the available commands in the Linux terminal window. To read the manual pages on a particular command, type the following:

man command

This will pull up the manual pages for the particular command that you are searching. Here’s the manual pages for the apropos command:

In the manual, the first line contains the name of the command you are reading about and the ID of the section that contains the manual page.

After the first line is a synopsis, which is a short description of the command that includes technical notation of all the options and/or arguments. Options are a way of executing the command, and an argument is what you execute it on. Optional arguments are put between square brackets.

After the synopsis is a longer description of the command, followed by a more in-depth overview of the available options, information about combining options, other related commands, and other information pertaining to the command.

Some commands have multiple man pages, like the “passwd” command. To see all pages about a command, use the “-a” option:

man -a passwd

The info pages contain more recent information and can be easier to use. Here’s what the menu of the info pages looks like:

To view the info pages on a command (replacing “command” with the actual name of the command you want to research, like “apropos”), type the following:

info command

To navigate the info pages, use the arrow keys to browse through text, the Enter key to read about a particular keyword, “P” and “N” keys to go to the previous or next subject, and the space bar to move one page further. Use “Q” to quit.

2. whatis and apropos commands

The whatis command gives brief information about a command and lists the first section in the man pages that contains a relevant page (in parenthesis after the command name).

If you’re entirely unsure where to start, the apropos command is a good way to search for keywords. For example, if you want to know how to start a browser, you can type apropos browser, which will pull up a list of all browser-related programs, including web browsers, file and FTP browsers, etc.

Here’s the apropos search results for “text”, which displays commands and programs that contain the phrase “text”:

 

3. Using the –help option

Most commands also have the option –help, which gives a short explanation of the command and a list of available options. When in doubt, this is a great way to get some quick and useful information on using a particular command and its possible extensions.

To use the –help option, type –help after a particular command, like the following example (also shown in the photo above):

apropos --help

The output looks like this:

 

Enough of the Terminal Window! Where’s the friggin’ Desktop??

Alright alright.. Remote Desktop Connection is an easy way to use the desktop view, also known as “Graphical User Interface,” or GUI for short.

1. Install Remote Desktop Connection on your Pi:

sudo apt-get install xrdp

2. Install Remote Desktop Connection on your PC (is already installed on Windows OS).

3. Open Remote Desktop Connection and log in using the “raspberrypi.local” IP (or find your Pi’s IP using command ifconfig). Ignore warning (click “yes”).

4. Log in with the Pi’s username and password.

If you haven’t changed your password yet, do so now. (Yes, I know I already told ya to do so but it is worth repeating since someone could actually hack into your Pi if you don’t change the default password.)

Now you can use the Pi’s GUI and do almost* everything via your PC!

*Sadly, we can’t play Minecraft in this mode as it uses too much data to be transferred via SSH. Using a VNC viewer is one option around this if you really want to play Minecraft remotely.

What is SSH, anyway?

SSH stands for “Secure SHell” — it is a “cryptographic network protocol for operating network services securely over an unsecured network.” – Wikipedia

… Uh, what?

In other words, SSH is a secure way to connect between one computer and another, even if the network through which you are connected is not secure.

For example, if you are on a shared network and you use SSH to remotely log into another computer, other folks on the shared network can’t see what you’re doing through the remote connection (although Snowden did release documents that showed the NSA can sometimes decrypt SSH).

Common uses of SSH include remote log in, like if you want to connect to a computer that lives a mile underground without having to, you know, actually go down there. (I used to work for a super cool dark matter experiment called DRIFT and this is how we would access the computers that controlled the detector because the computers lived in a mine about 3 miles underground.. too far to travel to update software!).

Here’s the full Wikipedia page on SSH — it’s super cool so check it out!

More to Explore!

Go forth and explore! Practice using the terminal window until you get comfortable and familiar with the basic commands.

Program the GPIO pins to do cool stuff! Need some ideas? Check out these tutorials:

1. Making a Soil Moisture Sensor

2. Building an Irrigation Controller (can be paried w/ Soil Moisture Sensor)

3. Bark Back: Install an IoT Pet Monitor

4. Expand on your Smart Home & add a Motion Triggered Music Player

Need parts?

Take apart old & broken electronics! Electronic toys are a great place to get motors and speakers. If you want better motors, take apart power tools.

Ask friends or find a repair shop for extra parts and wire, save power cables from old electronics and use them as power supplies or harvest them for wires and/or connectors, save old headphones and use them for audio projects.

Best piece of advice: think before you toss 🙂