Looking for a low-power yet bright mini display for your Pi project? Adafruit’s latest OLED screen could well fit the bill. An OLED (organic light-emitting diode) display offers high contrast combined with a low power draw, since it doesn’t require a backlight.
This article was written by Phil King and appears in The MagPi #63.
While numerous OLED screens are available, including a range from Adafruit itself, most require you to wire them up manually to the Raspberry Pi (or whatever device you’re using). The Pi Zero-sized OLED Bonnet takes the hassle out of connection: pre-assembled with a female header, it simply slots onto the Pi’s GPIO pins.
Available from Pimoroni in the UK, the OLED Bonnet is the big sibling of the 128×32 PiOLED, doubling the latter’s screen area while adding a mini joystick (four-way plus central push function) and two buttons. This would make it ideal for use as a mini menu system in, for example, a music player.
While the screen is monochrome – white on black – and obviously too low-res to use as a main Pi display, its high contrast enables it to show text with great clarity. Any standard TTF font can be used, and one of the Python examples downloaded after cloning the relevant GitHub repo is an old-school sine-wave scrolling text demo. Basic images, which may be converted to bitmaps and resized via PIL, can also be displayed.
Unlike an e-ink screen, the OLED Bonnet is even able to handle basic animations. While the frame rate is rather sluggish by default, it can be speeded up to about 15 fps by raising the I2C core baud rate to 1 MHz in the Raspberry Pi’s /boot/config.txt file.
As well as two GPIO pins for I2C communication with the Pi, the OLED Bonnet uses seven others for joystick and button inputs. That still leaves plenty of GPIO pins available for use in projects, although due to the full-size female header, you’ll need to break them out using something like a Pico HAT Hacker.
Last word
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With its high contrast and clarity, the OLED Bonnet is ideal as a mini status display or – taking advantage of the joystick and buttons – menu system. The screen’s low power draw (around 40 mA on average) is also an advantage for portable projects using battery power.
