Overview

A Feather board without ambition is a Feather board without FeatherWings! This is the FeatherWing OLED: it adds a 128x32 monochrome OLED plus 3 user buttons to any Feather main board. Using our Feather Stacking Headers or Feather Female Headers you can connect a FeatherWing on top of your Feather board and let the board take flight!

These displays are small, only about 1" diagonal, but very readable due to the high contrast of an OLED display. This screen is made of 128x32 individual white OLED pixels and because the display makes its own light, no backlight is required. This reduces the power required to run the OLED and is why the display has such high contrast; we really like this miniature display for its crispness! We also toss on a reset button and three mini tactile buttons called A B and C so you can add a mini user interface to your feather.

Tested works with all of our Feather boards. The OLED uses only the two I2C pins on the Feather, and you can pretty much stack it with any other FeatherWing, even ones that use I2C since that is a shared bus.

Pinouts

The OLED FeatherWing plugs into any Feather and adds a cute little display. To make it as cross-platform compatible as possible, we use only I2C to control the display. This is not as fast as SPI but it uses only two pins, can share the I2C bus and is fine for the small 128x32 pixel OLED.

Power Pins

OLED displays do not have a backlight, and are fairly low power, this display will draw about 10mA when in use. The display uses 3V power and logic so we just connect to the 3V and GND pins from the feather, as indicated above.

I2C Data Pins

The cute little OLED does all of the data transfer over the I2C pins, highlighed above SDA and SCL. No other pins are required. There are two 2.2K pullups to 3V on each.

These pins can be shared with other I2C devices.

The I2C address is 0x3C and cannot be changed

Optional Buttons

We had a little bit of space so we added three mini tactile buttons that you can use for user interface. We label them A B and C because each Feather has slightly different pin numbering schemes and we wanted to make it 'universal'

If you're using ATmega328P, Atmega32u4, ATSAMD51 M4 or ATSAMD21 M0 Feather

  • Button A is #9 (note this is also used for the battery voltage divider so if you want to use both make sure you disable the pullup when you analog read, then turn on the pullup for button reads)
  • Button B is #6
  • Button C is #5

If you're using ESP8266:

  • Button A is #0
  • Button B is #16
  • Button C is #2

If you're using WICED/STM32 Feather

  • Button A is #PA15
  • Button B is #PC7
  • Button C is #PC5

Button B has a 100K pullup on it so it will work with the ESP8266 (which does not have an internal pullup available on that pin). You will need to set up a pullup on all other pins for the buttons to work.

Reset Button

Sometimes its nice to be able to restart your program, so we also have a reset button. It is tied to the RST pin marked above.

Assembly

Prepare the header strip:

Cut the strip to length if necessary. It will be easier to solder if you insert it into a breadboard - long pins down

Add the FeatherWing:

Place the featherwing over the pins so that the short pins poke through the two rows of breakout pads

And Solder!

Be sure to solder all pins for reliable electrical contact.

(For tips on soldering, be sure to check out our Guide to Excellent Soldering).

 

Start by soldering the first row of header

Now flip around and solder the other row completely

You're done with the two header strips.

 

Check your solder joints visually and continue onto the next steps

OK You're done! You can now plug your FeatherWing into your Feather and get your OLED on! 

Arduino Code

The OLED display we use is well supported and works for all Feathers, all you need is a little library support and you will be drawing in no time!

Install Arduino Libraries

Using the OLED FeatherWing with Arduino sketches requires that two libraries be installed: Adafruit_SSD1306, which handles the low-level communication with the hardware, and Adafruit_GFX, which builds atop this to add graphics functions like lines, circles and text.

In recent versions of the Arduino IDE software (1.6.2 and later), this is most easily done through the Arduino Library Manager, which you’ll find in the “Sketch” menu: Sketch→Include Library→Manage Libraries…

Enter “ssd1306” in the search field, locate the Adafruit SSD1306 library and select “Install” (or “Upgrade” if you have an older version). Then repeat the same for “gfx” and the Adafruit GFX library.

We also have a great tutorial on Arduino library installation here:
http://learn.adafruit.com/adafruit-all-about-arduino-libraries-install-use

Run Example Code

We have a basic demo that works with all Feathers, so compile/upload this sketch:

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

Adafruit_SSD1306 display = Adafruit_SSD1306(128, 32, &Wire);

// OLED FeatherWing buttons map to different pins depending on board:
#if defined(ESP8266)
  #define BUTTON_A  0
  #define BUTTON_B 16
  #define BUTTON_C  2
#elif defined(ESP32)
  #define BUTTON_A 15
  #define BUTTON_B 32
  #define BUTTON_C 14
#elif defined(ARDUINO_STM32_FEATHER)
  #define BUTTON_A PA15
  #define BUTTON_B PC7
  #define BUTTON_C PC5
#elif defined(TEENSYDUINO)
  #define BUTTON_A  4
  #define BUTTON_B  3
  #define BUTTON_C  8
#elif defined(ARDUINO_FEATHER52832)
  #define BUTTON_A 31
  #define BUTTON_B 30
  #define BUTTON_C 27
#else // 32u4, M0, M4, nrf52840 and 328p
  #define BUTTON_A  9
  #define BUTTON_B  6
  #define BUTTON_C  5
#endif

void setup() {
  Serial.begin(9600);

  Serial.println("OLED FeatherWing test");
  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Address 0x3C for 128x32

  Serial.println("OLED begun");

  // Show image buffer on the display hardware.
  // Since the buffer is intialized with an Adafruit splashscreen
  // internally, this will display the splashscreen.
  display.display();
  delay(1000);

  // Clear the buffer.
  display.clearDisplay();
  display.display();

  Serial.println("IO test");

  pinMode(BUTTON_A, INPUT_PULLUP);
  pinMode(BUTTON_B, INPUT_PULLUP);
  pinMode(BUTTON_C, INPUT_PULLUP);

  // text display tests
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.print("Connecting to SSID\n'adafruit':");
  display.print("connected!");
  display.println("IP: 10.0.1.23");
  display.println("Sending val #0");
  display.setCursor(0,0);
  display.display(); // actually display all of the above
}

void loop() {
  if(!digitalRead(BUTTON_A)) display.print("A");
  if(!digitalRead(BUTTON_B)) display.print("B");
  if(!digitalRead(BUTTON_C)) display.print("C");
  delay(10);
  yield();
  display.display();
}

You should see the OLED display a splash screen then spit out some text (it’s a make-believe WiFi connection status screen…this doesn’t actually do anything, just showing how typical project might look). If you press the A B or C buttons it will also print those out.

Do more!

You can use any of the Adafruit GFX library commands to draw onto your OLED, that means that you get all sorts of shapes, fonts, lines, etc available. Check out GFX for all the underlying graphics support functions and how they work

Remember you need to call display() after drawing to refresh the screen!

CircuitPython

Adafruit CircuitPython Module Install

To use the SSD1306 with your Adafruit CircuitPython board you'll need to install the Adafruit_CircuitPython_SSD1306 module on your board.

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Bundle Install

Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle.  Our introduction guide has a great page on how to install the library bundle for both express and non-express boards.

Remember for non-express boards like the, you'll need to manually install the necessary libraries from the bundle:

  • adafruit_ssd1306
  • adafruit_bus_device
  • adafruit_register

If your board supports USB mass storage, like the M0-based boards, then simply drag the files to the board's file system.

If your board doesn't support USB mass storage, like the ESP8266, then use a tool like ampy to copy the file to the board. You can use the latest version of ampy and its new directory copy command to easily move module directories to the board.

Furthermore, CircuitPython for smaller M0 boards like the Trinket and Gemma do not have the framebuf module built in to save flash space. So, please download and install the pure Python implementation of framebuf and copy it to lib folder of the board as well. You do not need to do this for Express CircuitPython boards (they have enough space for framebuf!)

Before continuing make sure your board's lib folder or root filesystem has at least the adafruit_ssd1306adafruit_bus_deviceadafruit_register, and if necessary framebuf folders/modules copied over.

Usage

The following section will show how to control the LED backpack from the board's Python prompt / REPL.  You'll walk through how to control the LED display and learn how to use the CircuitPython module built for the display.

Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.

I2C Initialization

If your display is connected to the board using I2C (like if using a Feather and the FeatherWing OLED) you'll first need to initialize the I2C bus.  First import the necessary modules:

Download: file
import board
import busio as io

Note if you're using the ESP8266 or other boards which do not support hardware I2C you need to import from the bitbangio module instead of busio:

Download: file
import board
import bitbangio as io

Now for either board run this command to create the I2C instance using the default SCL and SDA pins (which will be marked on the boards pins if using a Feather or similar Adafruit board):

Download: file
i2c = io.I2C(board.SCL, board.SDA)

After initializing the I2C interface for your firmware as described above you can create an instance of the SSD1306 I2C driver by running:

Download: file
import adafruit_ssd1306
oled = adafruit_ssd1306.SSD1306_I2C(128, 32, i2c)

Note that the first two parameters to the SSD1306_I2C class initializer are the width and height of the display in pixels.  Be sure to use the right values for the display you're using!

128 x 64 size OLEDs (or changing the I2C address)

If you are using a 128x64 display, the I2C address is probably different (0x3d), unless you've changed it by soldering some jumpers:

Download: file
oled = adafruit_ssd1306.SSD1306_I2C(128, 64, i2c, addr=0x3d)

Adding hardware reset pin

If you have a reset pin (which may be required if your OLED does not have an auto-reset chip like the FeatherWing) also pass in a reset pin like so:

Download: file
from digitalio import DigitalInOut

reset_pin = DigitalInOut(board.D5) # any pin!
oled = adafruit_ssd1306.SSD1306_I2C(128, 32, i2c, reset=reset_pin)

At this point your I2C bus and display are initialized, skip down to the drawing section.

SPI Initialization

If your display is connected to the board using SPI you'll first need to initialize the SPI bus. Run the following commands:

Download: file
import adafruit_ssd1306
import board
import busio
from digitalio import DigitalInOut

spi = busio.SPI(board.CLK, MOSI=board.MOSI, MISO=board.MISO)
dc_pin = DigitalInOut(board.D5)    # any pin!
reset_pin = DigitalInOut(board.D6) # any pin!
cs_pin = DigitalInOut(board.D9)    # any pin!

oled = adafruit_ssd1306.SSD1306_SPI(128, 32, spi, dc_pin, reset_pin, cs_pin)

Note the first two parameters to the SSD1306_SPI class initializer are the width and height of the display in pixels.  Be sure to use the right values for the display you're using!

The next parameters to the initializer are the pins connected to the display's DCreset, and CS lines in that order.  Again make sure to use the right pin names as you have wired up to your board!

Drawing

The SSD1306 module currently supports a basic set of commands to draw on the display.  You can set individual pixels, fill the screen, and write lines of text.  There aren't yet more advanced functions like line drawing, etc. but check the module GitHub repository for future releases which might include more functions.

To fill or clear the entire screen use the fill function.  This function takes a parameter which specifies the color to fill with, either 0 for black or 1 for white.  For example to fill the screen white:

Download: file
oled.fill(1)
oled.show()

Notice the fill function doesn't actually change the display.  You must call show after making drawing commands to send the updated pixel data to the display!

To clear the screen to black just call fill again but with the color 0:

Download: file
oled.fill(0)
oled.show()

To set a pixel use the pixel function.  This function takes the following parameters:

  • Pixel X position
  • Pixel Y position
  • Pixel color (0 = black, 1 = white)

For example to set the first pixel white:

Download: file
oled.pixel(0, 0, 1)
oled.show()

Try setting other pixels white by changing the X and Y position.  Remember you have to call show after setting pixels to see them appear!

You can write a line of text with the text function.  This function takes the following parameters:

  • String of text
  • Text X position
  • Text Y position
  • Optional text color (0 = black, 1 = white, the default)

For example to clear the screen and then write two lines of text:

Download: file
oled.fill(0)
oled.text('Hello', 0, 0)
oled.text('World', 0, 10)
oled.show()

Note that not all boards support built-in text rendering.  In particular the non-express boards like Gemma and Trinket M0 don't have the memory to build in text drawing.  You can however on those boards load a separate Python text drawing library to draw text.  See the Drawing Text guide!

Notice the second line of text starts at Y position 10, this moves it down the display 10 pixels so it's below the first line of text.  The font used by the text function is 8 pixels tall so a size of 10 gives a bit of room between the lines.

Finally you can invert the display colors with the invert function:

Download: file
oled.invert(True)

Note that the invert function doesn't need to have show called after it to see the change.

To go back to a non-inverted display run:

Download: file
oled.invert(False)

That's all there is to drawing on the SSD1306 OLED display with CircuitPython!  The drawing functions are basic but provide building blocks for more advanced usage.  For example you can display text with sensor readings or other state, or even program a simple game like pong!

You can find more drawing functions for basic shapes and text by following these guides (which work with both CircuitPython and MicroPython):

Troubleshooting

Display does not work on initial power but does work after a reset.

The OLED driver circuit needs a small amount of time to be ready after initial power. If your code tries to write to the display too soon, it may not be ready. It will work on reset since that typically does not cycle power. If you are having this issue, try adding a small amount of delay before trying to write to the OLED.

In Arduino, use delay() to add a few milliseconds before calling oled.begin(). Adjust the amount of delay as needed to see how little you can get away with for your specific setup.

Download

This guide was first published on Apr 26, 2016. It was last updated on 2018-12-04 12:31:08 -0500.