Drawing Graphics with an OLED Display

Are you skipping ahead?

Make sure you have already installed the custom tinyCore board library and setup your Arduino IDE using the Get Started tutorial!

Okay, but first:

What the hell is “I2C”?

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I2C (pronounced “I-squared-C”) stands for Inter-Integrated Circuit. It’s basically a communication protocol that allows multiple electronic parts to talk to your tinyCore using just two wires!

Instead of needing a separate pin for every single button or light, I2C uses a “bus” system.

• SDA (Serial Data): The wire that actually sends the messages back and forth.
• SCL (Serial Clock): The wire that keeps the timing perfect like a metronome.

Because I2C allows multiple devices on the same two wires, each device has its own unique “address” (like a digital house number) so the tinyCore knows exactly who it’s talking to.

For this tutorial, we are using the classic 0.96 inch OLED Display. These are incredibly popular, super bright, and use I2C to receive drawing commands!

1. Wiring the Display

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Because I2C is a shared bus, we can actually wire this up to the exact same pins we used for the IMU!

1. GND → GND on tinyCore
2. VCC → 3.3V on tinyCore
3. SCL → SCL on tinyCore
4. SDA → SDA on tinyCore

Note: Double-check your specific display! Some manufacturers swap the order of the GND and VCC pins at the top.

Alternatively…

If you are using the OLED Display included with the tinyKit, you can use the QWIIC cable to connect it!

2. Install the Libraries

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To draw on this screen without having to manually calculate individual pixel memory addresses, we are going to use two helpful libraries from Adafruit.

1. Open the Library Manager icon in your Arduino IDE.
2. Search for “Adafruit SSD1306” and click INSTALL. (If it asks to install missing dependencies like Adafruit BusIO, say yes!)
3. Next, search for “Adafruit GFX” and install that as well. This library gives us the math needed to draw circles, lines, and text.

3. Hello World (Text on Screen!)

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Let’s test our display by printing some simple text.

Display Buffers

Notice how we called display.println() but nothing actually happens until we call display.display()?

This is called “buffering”. The tinyCore does all the math in its own memory first, and then blasts the entire finished frame to the OLED all at once. This prevents the screen from flickering while it draws.

4. Interactive Physics: The IMU Digital Hourglass

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Displaying static text is great, but your tinyCore has a built-in 6DOF IMU! Let’s combine the two and make an interactive digital hourglass.

When you tilt your tinyCore left, right, or upside down, the “sand” (pixels) on the screen will fall with gravity using the accelerometer data!

You’ll need the Adafruit_LSM6DSOX library installed (which you should already have from the IMU tutorial).

Why does the sand clump up sometimes?

Our simple code above lacks Particle Collision! We check if the sand hits the glass walls of the hourglass, but we aren’t checking if a sand particle hits another sand particle.

Writing collision math for 60 particles checking against each other every frame is computationally heavy (an $O(N^2)$ problem). If you want a fun challenge, see if you can add basic collision detection so the sand piles up!

5. Troubleshooting

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My screen is completely black!

• Check your wiring. VCC and GND are easy to swap by accident.
• Check your I2C address. Most are 0x3C, but some cheap clones use 0x3D. Try changing #define SCREEN_ADDRESS in the code.
• Run the I2C Scanner code from the IMU tutorial to see if the tinyCore even detects the screen!

The code won’t compile!

• Ensure you have both the Adafruit GFX and Adafruit SSD1306 libraries installed. The screen library relies on the GFX library to do the math.

What’s Next?

Now that you have a visual output, you can build proper user interfaces!

Ready to try:

• Building a menu system with Reading a Button Press?
• Adding audio feedback to your menus with Controlling a Buzzer?

Having trouble?

Send us an email at support@mr.industries or join our Discord for help!