Display Wings let you add a monochrome or color display for lots of data. These are very popular, as you can imagine, for adding a user interface.
These Wings work with all Feathers.
You can only really use one display at a time. The OLED Featherwing uses only I2C and works with any other Wings. The TFT 'wing uses a lot of pins, so works best with only I2C Wings.
This tiny Wing is so cute, and it has a 128x32 monochrome OLED display. OLEDs have a crisp and high-contrast look, so they are great for indoor and some outdoor use. There's no backlight so they use little power (only as much as the pixels that are lit).
The OLED is connected over I2C so it uses only two pins. In addition, there are 3 little buttons connected directly to three GPIO pins. You can use the buttons to add basic interactivity. Only one OLED FeatherWing can be used with a Feather board.
If you need a bigger and more colorful screen, the TFT FeatherWing has just about everything. There is a 320x240 full-color TFT display. There is also a resistive touchscreen on top, for interactivity. On the bottom is a microSD card holder so you can store images or data to be displayed. We also toss in an on-off switch.
The display is much bigger than the OLED, and uses the SPI port for communication with the TFT/touch/SD card.
The Wing requires an additional two pins for the TFT. One additional pin if you are using the touch screen, and one extra pin if using SD interface. (So, SPI + 4 GPIO pins max if using all three)
Unlike other wings, this one is fully assembled and the feather plugs into the bottom. If you want to stack Wings, you'll need to solder stacking headers to the Feather, then stack on top of that.