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.
Below covers how to wire the display to a Raspberry Pi.
Since there's dozens of Linux computers/boards you can use, below shows 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, that's SLCK.
- MOSI connects to SPI MOSI. On the Raspberry Pi, that's also MOSI.
- CS connects to the SPI Chip Select pin. Here uses CE0.
- RST connects to the Reset pin. Here uses GPIO 24 but this can be changed later.
- D/C connects to the SPI Chip Select pin. This uses 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
PIL, the Python Imaging Library, will also be needed to display 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
You can install NumPy which allows for additional speed. This can be installed with the following command:
sudo apt-get install python3-numpy
Running the Code
Next to run the code, you will need to do a simple modification so the CircuitPython code runs on Python.
cd ~ wget https://github.com/adafruit/Adafruit_CircuitPython_ST7789/raw/main/examples/st7789_170x320_1.9_simpletest.py
Next, edit the script and make the following changes to use the correct pins:
tft_cs = board.CE0 tft_dc = board.D25 tft_rst = 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
BORDER_WIDTH = 20
TEXT_SCALE = 3
# Release any resources currently in use for the displays
displayio.release_displays()
spi = board.SPI()
tft_cs = board.D5
tft_dc = board.D6
tft_rst = board.D9
display_bus = FourWire(spi, command=tft_dc, chip_select=tft_cs, reset=tft_rst)
display = ST7789(display_bus, width=320, height=170, colstart=35, rotation=90)
# Make the display context
splash = displayio.Group()
display.root_group = splash
color_bitmap = displayio.Bitmap(display.width, display.height, 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(
display.width - (BORDER_WIDTH * 2), display.height - (BORDER_WIDTH * 2), 1
)
inner_palette = displayio.Palette(1)
inner_palette[0] = 0xAA0088 # Purple
inner_sprite = displayio.TileGrid(
inner_bitmap, pixel_shader=inner_palette, x=BORDER_WIDTH, y=BORDER_WIDTH
)
splash.append(inner_sprite)
# Draw a label
text_area = label.Label(
terminalio.FONT,
text="Hello World!",
color=0xFFFF00,
scale=TEXT_SCALE,
anchor_point=(0.5, 0.5),
anchored_position=(display.width // 2, display.height // 2),
)
splash.append(text_area)
while True:
pass
Python Installation of RGB Display Library
The other library that you can use to draw to displays in Python is the RGB Display library. This library allows you to more directly use PIL so if you wanted to draw a JPG image, for instance, or other advanced graphics, then you can easily do so. To install the library, run this command:
sudo pip3 install adafruit-circuitpython-rgb-display
Displaying a JPG Image
To display an image other than a Bitmap such as a JPG, you just need to load it in with Pillow. To demonstrate this, download this image of blinka:
You can download it straight onto you Pi with this command:
wget https://cdn-learn.adafruit.com/assets/assets/000/110/221/original/adafruit_products_blinka.jpg mv adafruit_products_blinka.jpg blinka.jpg
You can download the script to your Pi with this command:
wget https://github.com/adafruit/Adafruit_CircuitPython_RGB_Display/raw/main/examples/rgb_display_pillow_image.py
Run the Script
You will need to modify the script by commenting out a few lines of the ILI9341 display initializer. Leave everything else that including the line that contains cs=cs_pin, alone. The code with the commented out part should look like this:
#disp = ili9341.ILI9341(
# spi,
# rotation=90, # 2.2", 2.4", 2.8", 3.2" ILI9341
cs=cs_pin,
dc=dc_pin,
Then you will need to uncomment the line that for this display:
disp = st7789.ST7789(spi, rotation=270, width=170, height=320, x_offset=35, # 1.9" ST7789
Now you can run the script with this command:
sudo python3 rgb_display_pillow_image.py
Your display should look like this:
# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
"""
Be sure to check the learn guides for more usage information.
This example is for use on (Linux) computers that are using CPython with
Adafruit Blinka to support CircuitPython libraries. CircuitPython does
not support PIL/pillow (python imaging library)!
Author(s): Melissa LeBlanc-Williams for Adafruit Industries
"""
import digitalio
import board
from PIL import Image, ImageDraw
from adafruit_rgb_display import ili9341
from adafruit_rgb_display import st7789 # pylint: disable=unused-import
from adafruit_rgb_display import hx8357 # pylint: disable=unused-import
from adafruit_rgb_display import st7735 # pylint: disable=unused-import
from adafruit_rgb_display import ssd1351 # pylint: disable=unused-import
from adafruit_rgb_display import ssd1331 # pylint: disable=unused-import
# Configuration for CS and DC pins (these are PiTFT defaults):
cs_pin = digitalio.DigitalInOut(board.CE0)
dc_pin = digitalio.DigitalInOut(board.D25)
reset_pin = digitalio.DigitalInOut(board.D24)
# Config for display baudrate (default max is 24mhz):
BAUDRATE = 24000000
# Setup SPI bus using hardware SPI:
spi = board.SPI()
# pylint: disable=line-too-long
# Create the display:
# disp = st7789.ST7789(spi, rotation=90, # 2.0" ST7789
# disp = st7789.ST7789(spi, height=240, y_offset=80, rotation=180, # 1.3", 1.54" ST7789
# disp = st7789.ST7789(spi, rotation=90, width=135, height=240, x_offset=53, y_offset=40, # 1.14" ST7789
# disp = st7789.ST7789(spi, rotation=90, width=172, height=320, x_offset=34, # 1.47" ST7789
# disp = st7789.ST7789(spi, rotation=270, width=170, height=320, x_offset=35, # 1.9" ST7789
# disp = hx8357.HX8357(spi, rotation=180, # 3.5" HX8357
# disp = st7735.ST7735R(spi, rotation=90, # 1.8" ST7735R
# disp = st7735.ST7735R(spi, rotation=270, height=128, x_offset=2, y_offset=3, # 1.44" ST7735R
# disp = st7735.ST7735R(spi, rotation=90, bgr=True, width=80, # 0.96" MiniTFT Rev A ST7735R
# disp = st7735.ST7735R(spi, rotation=90, invert=True, width=80, # 0.96" MiniTFT Rev B ST7735R
# x_offset=26, y_offset=1,
# disp = ssd1351.SSD1351(spi, rotation=180, # 1.5" SSD1351
# disp = ssd1351.SSD1351(spi, height=96, y_offset=32, rotation=180, # 1.27" SSD1351
# disp = ssd1331.SSD1331(spi, rotation=180, # 0.96" SSD1331
disp = ili9341.ILI9341(
spi,
rotation=90, # 2.2", 2.4", 2.8", 3.2" ILI9341
cs=cs_pin,
dc=dc_pin,
rst=reset_pin,
baudrate=BAUDRATE,
)
# pylint: enable=line-too-long
# Create blank image for drawing.
# Make sure to create image with mode 'RGB' for full color.
if disp.rotation % 180 == 90:
height = disp.width # we swap height/width to rotate it to landscape!
width = disp.height
else:
width = disp.width # we swap height/width to rotate it to landscape!
height = disp.height
image = Image.new("RGB", (width, height))
# Get drawing object to draw on image.
draw = ImageDraw.Draw(image)
# Draw a black filled box to clear the image.
draw.rectangle((0, 0, width, height), outline=0, fill=(0, 0, 0))
disp.image(image)
image = Image.open("blinka.jpg")
# Scale the image to the smaller screen dimension
image_ratio = image.width / image.height
screen_ratio = width / height
if screen_ratio < image_ratio:
scaled_width = image.width * height // image.height
scaled_height = height
else:
scaled_width = width
scaled_height = image.height * width // image.width
image = image.resize((scaled_width, scaled_height), Image.BICUBIC)
# Crop and center the image
x = scaled_width // 2 - width // 2
y = scaled_height // 2 - height // 2
image = image.crop((x, y, x + width, y + height))
# Display image.
disp.image(image)
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