It's easy to use display breakouts with Python and the Adafruit Blinka Displayio module. This module allows you to easily write Python code to control the display.
We'll cover how to wire the display to your Raspberry Pi. First assemble your display.
Since there's dozens of Linux computers/boards you can use we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported.
Connect the display as shown below to your Raspberry Pi.
- Vin connects to the Raspberry Pi's 3V pin
- GND connects to the Raspberry Pi's ground
- CLK connects to SPI clock. On the Raspberry Pi, thats SLCK
- MOSI connects to SPI MOSI. On the Raspberry Pi, thats also MOSI
- CS connects to our SPI Chip Select pin. We'll be using CE0
- RST connects to our Reset pin. We'll be using GPIO 24 but this can be changed later.
- D/C connects to our SPI Chip Select pin. We'll be using GPIO 25, but this can be changed later as well.
Setup
You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling SPI on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!
Python Installation of ST7789 Library
Once that's done, from your command line run the following command:
sudo pip3 install adafruit-circuitpython-st7789 adafruit-circuitpython-display-text
If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!
If that complains about pip3 not being installed, then run this first to install it:
sudo apt-get install python3-pip
Pillow Library
We also need PIL, the Python Imaging Library, to allow graphics and using text with custom fonts. There are several system libraries that PIL relies on, so installing via a package manager is the easiest way to bring in everything:
sudo apt-get install python3-pil
NumPy Library
A recent improvement of the RGB_Display library makes use of NumPy for additional speed. This can be installed with the following command:
sudo apt-get install python3-numpy
cd ~ wget https://github.com/adafruit/Adafruit_CircuitPython_ST7789/raw/main/examples/st7789_280x240_simpletest.py
Next, edit the script and make the following changes to use the correct pins:
spi = board.SPI()
tft_cs = board.CE0
tft_dc = board.D25
display_bus = displayio.FourWire(
spi, command=tft_dc, chip_select=tft_cs, reset=board.D24
)
Now go ahead and run the script, the output should look like this:
# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
"""
This test will initialize the display using displayio and draw a solid green
background, a smaller purple rectangle, and some yellow text.
"""
import board
import terminalio
import displayio
# Starting in CircuitPython 9.x fourwire will be a seperate internal library
# rather than a component of the displayio library
try:
from fourwire import FourWire
except ImportError:
from displayio import FourWire
from adafruit_display_text import label
from adafruit_st7789 import ST7789
# Release any resources currently in use for the displays
displayio.release_displays()
spi = board.SPI()
tft_cs = board.D5
tft_dc = board.D6
display_bus = FourWire(spi, command=tft_dc, chip_select=tft_cs, reset=board.D9)
display = ST7789(display_bus, width=280, height=240, rowstart=20, rotation=90)
# Make the display context
splash = displayio.Group()
display.root_group = splash
color_bitmap = displayio.Bitmap(280, 240, 1)
color_palette = displayio.Palette(1)
color_palette[0] = 0x00FF00 # Bright Green
bg_sprite = displayio.TileGrid(color_bitmap, pixel_shader=color_palette, x=0, y=0)
splash.append(bg_sprite)
# Draw a smaller inner rectangle
inner_bitmap = displayio.Bitmap(240, 200, 1)
inner_palette = displayio.Palette(1)
inner_palette[0] = 0xAA0088 # Purple
inner_sprite = displayio.TileGrid(inner_bitmap, pixel_shader=inner_palette, x=20, y=20)
splash.append(inner_sprite)
# Draw a label
text_group = displayio.Group(scale=3, x=37, y=120)
text = "Hello World!"
text_area = label.Label(terminalio.FONT, text=text, color=0xFFFF00)
text_group.append(text_area) # Subgroup for text scaling
splash.append(text_group)
while True:
pass
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