Workshop: Introduction to Microcontrollers with Arduino

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(Generally, this workshop is offered at least once every week on a rotating basis. Check the DaBL calendar for up-to-date availability!)


This Workshop will introduce you to the world of microcontrollers: tiny computers that do a specific task. Effectively, what you'll be doing today is interfacing hardware and software together: you will write code which will interact with the outside world!

In order to accomplish this, you're going to be using Arduino. Arduino can refer to many things (a company, a software suite, a board, a programming language); in general, Arduino is an ecosystem in which you can conveniently program microcontrollers to interact with the outside world. It’s the easiest (as well as most ubiquitous) way to connect hardware with software, and the easiest way to get into embedded programming.

The Arduino IDE is a software suite which packages up all the functionality of programming microcontrollers in a higher level language (in this case, the Arduino language!). Its underlying compiler inherits from the C++ language (and by extension, C), so to those who have used C++, C, or any language with a C-like syntax, this will look very familiar.

Hardware Setup

You’ll be using a microcontroller today called the Teensy 4.0. As its name suggests, it’s pretty small! As such, the silkscreen (the text that appears on the faces of the printed circuit board, usually indicating things like pin labels) is minimal. In order to actually utilize the Teensy, you’ll need its pinout:

Teensy 3.2 3.1 pinout.png

Set up the Teensy on the breadboard

Note that in this example the green wire is connected to 5V.
This Teensy and breadboard are ready to go!

If it hasn’t already been done for you, carefully insert the Teensy onto the far edge of the breadboard. Make sure the Teensy straddle’s the gap, so that each row of pins sits on either half (top or bottom).

If the horizontal power rails on your breadboard are separated (like the breadboard in the picture). We will need to use small wires to connect both sides. This extends the horizontal rails to span the entire length of the breadboard.

Connect the top upper rail and the top lower rail. Similarly, connect the top lower rail to the bottom lower rail. Finally, connect the top-most wire to power (3.3V) and connect the wire below power to ground (GND). If all is correct we now have both a ground and power rail for each half of the breadboard.

Software setup

You're going to need two pieces of software to work with the microcontroller.

Download and install

  1. Download and install the Arduino IDE on your operating system of choice. (Note: if you're using Windows, use the installer, not the app!)
  2. Download and install Teensyduino, which adds Teensy support to the Arduino IDE. Just follow the prompts; you don’t need to install all the libraries, but if you ever want to work with Teensies in the future, it’s worth taking the time to install them now.

The which, the where, and the how

In order to get the Arduino IDE up and running with your board - regardless of which board it happens to be - you must answer for it three questions: the which, the where, and the how.

  1. Which board are you using?
    • Navigate to Tools → Board and select Teensy 4.0
  2. Where is the board connected?
    • Navigate to Tools → Port and:
      • Windows: select COMX, where X is the largest number (it should also say Teensy 4.0)
      • OSX: select /dev/cu.usbmodemXXXXXXXX Serial (Teensy 4.0) , where XXXXXX is some number. This may not show up with Teensy.
      • (You can see that neither of these operating systems handle hardware communication ports very elegantly.)
  3. How are you programming the board? So far, you’ve used the mEDBG device for programming. Teensy won’t work with that - but it will work with the default programmer, the AVRISP mkII.
    • Navigate to Tools → Programmer and select AVRISP mkII.


Each Activity in this Workshop will have a Hardware component and a Software component. It will be important to remember this, to begin to compartmentalize each task you must complete! Ultimately, this workshop will consist of two main objectives: how to control digital pins (both as inputs and outputs) and how to control an analog pins (both as inputs and 'outputs').

Activity 01: Digital output (aka 'Hello World' for hardware)

In this activity, you will use a pin on the microcontroller to blink an LED.

  1. Navigate to File → Examples → 01.Basics → Blink.
    The code which appears should look something like this:
    Code for teensy.png
  2. Upload the code to your board using the button or CTRL+U. This is actually a compile and program. If you get any errors, ask for help. Assuming it has programmed correctly, you should now see the onboard LED blinking!
  3. Fiddle with the delay times and reprogram to see how you can affect the speed of the LED blinking.
  4. Connect an LED and a 220Ω resistor to D9, and then change to code to reference this new LED’s pin.
  5. Compile and Program to test.

NOTE: There is a button on the Teensy. This button does not do what you think it does. This button is a program button, meaning that when you press it, the device takes the most-recently compiled code and sticks it in its program memory. This is not a reset button!

Activity 02: Digital Input (aka a button)

In this activity, you will use a button to control an LED - all through software. Leave the LED and 220Ω resistor connected to D9 like in the previous activity.

  1. Navigate to File → Examples → 02.Digital → Button.
  2. Connect a button to D2.
  3. In the code, change the button pin to D2, and the LED pin to D9.
  4. Make the following change to the code
    pinMode(buttonPin, INPUT_PULLUP);
  5. Compile and Program.
  6. Modify the code so that when you press the button the LED turns on, and when you are not pressing the button, the LED turns off.

Activity 03: Analog Input (aka knobtwisting)

In this activity, you will use a knob to control the blinking speed of an LED - all through software.

  1. Navigate to File → Examples → 03.Analog → AnalogInput.
  2. Connect a potentiometer to A5.
  3. Change the LED pin to D9. Additionally, change the analog input pin to A5.
  4. Compile and Program, and turn the pot to change the speed at which the LED blinks!

There isn't a way (yet) to see exactly how long each of those delays is happening for. Let's change that. You're going to add some debugging functionality to your code - by incorporating the Serial Monitor.

  1. In the setup function, add the following line:
    This initializes the Serial communications protocol.
  2. Now, in loop, after you’ve read the value of the analog pin, add the following line:
    (The method name reads as “print line”.)
  3. Compile and program the code, and once it’s successful, open the Serial Monitor with CTRL+SHIFT+M or by going to Tools → Serial Monitor. You should see values printing out on this screen; turn the potentiometer, and the value will change! This number is what is being used as the delay time (in ms) in the code.

ERROR: OH NO I CAN’T OPEN THE SERIAL MONITOR / OH NO I CAN’T PROGRAM ANYMORE. The Serial Monitor uses the same communication port as the Programmer - you can’t use both at the same time. Program the device, then open the Serial Monitor. If it’s still not working, check to make sure the IDE knows where the board is connected.

Activity 04: Analog 'Output' (aka breathe)

In this activity, you will program an LED to fade in and out. There is no input control.

  1. Navigate to File → Examples → 03.Analog → Fading.
  2. Compile and Program the code. your LED’s brightness should be fading up and down!

Activity 05: CHALLENGE

Using all your newly-acquired hardware and software prowess, create a device which directly controls the brightness of an LED with a knob.

Workshop Checklist

Learning Objectives

By the end of this Workshop, you should understand:

  1. What a microcontroller is
  2. How to compile programs for a Teensy
  3. The difference between analog and digital inputs/outputs.
  4. Using the serial monitor for debugging purposes

Measurable Outcomes

By the end of this Workshop, you should be able to:

  1. Use the Arduino IDE and Teensyduino
  2. Make an LED blink (Digital Outputs)
  3. Use a button to control an LED (Digital Inputs)
  4. Use a potentiometer (Analog Outputs)
  5. Change the brightness of an LED (Analog Inputs)
  6. Create a device that integrates everything we learned (control an LED's brightness with a potentiometer)