Python usage
OLED displays can be driven with python using the various implementations in the
luma.oled.device
package. There are several device classes available
and usage is very simple if you have ever used Pillow or PIL.
To begin you must import the device class you will be using and the interface class that you will use to communicate with your device:
In this example, we are using an I2C interface with a ssd1306 display.
from luma.core.interface.serial import i2c, spi, pcf8574
from luma.core.interface.parallel import bitbang_6800
from luma.core.render import canvas
from luma.oled.device import ssd1306, ssd1309, ssd1325, ssd1331, sh1106, sh1107, ws0010
# rev.1 users set port=0
# substitute spi(device=0, port=0) below if using that interface
# substitute bitbang_6800(RS=7, E=8, PINS=[25,24,23,27]) below if using that interface
serial = i2c(port=1, address=0x3C)
# substitute ssd1331(...) or sh1106(...) below if using that device
device = ssd1306(serial)
The display device should now be configured for use.
The device classes all expose a display()
method which takes an image with
attributes consistent with the capabilities of the device. However, for most
cases when drawing text and graphics primitives, the canvas class should be used
as follows:
with canvas(device) as draw:
draw.rectangle(device.bounding_box, outline="white", fill="black")
draw.text((30, 40), "Hello World", fill="white")
The luma.core.render.canvas
class automatically creates an PIL.ImageDraw
object of the correct dimensions and bit depth suitable for the device, so you
may then call the usual Pillow methods to draw onto the canvas.
As soon as the with scope is ended, the resultant image is automatically
flushed to the device’s display memory and the PIL.ImageDraw
object is
garbage collected.
Note
When a program ends, the display is automatically cleared. This means that a fast program that ends quickly may never display a visible image.
Color Model
Any of the standard PIL.ImageColor
color formats may be used, but since
the SSD1306, SH1106, SH1107 and WS0010 OLEDs are monochrome, only the HTML color names
"black"
and "white"
values should really be used; in fact, by default,
any value other than black is treated as white. The luma.core.render.canvas
object does have a dither
flag which if set to True
, will convert color drawings
to a dithered monochrome effect (see the 3d_box.py example, below).
with canvas(device, dither=True) as draw:
draw.rectangle((10, 10, 30, 30), outline="white", fill="red")
There is no such constraint on the SSD1331 or SSD1351 OLEDs, which features 16-bit RGB colors: 24-bit RGB images are downsized to 16-bit using a 565 scheme.
The SSD1322, SSD1325 and SSD1362 OLEDs all support 16 greyscale graduations: 24-bit RGB images are downsized to 4-bit using a Luma conversion which is approximately calculated as follows:
Y' = 0.299 R' + 0.587 G' + 0.114 B'
Landscape / Portrait Orientation
By default the display will be oriented in landscape mode (128x64 pixels for
the SSD1306, for example). Should you have an application that requires the
display to be mounted in a portrait aspect, then add a rotate=N
parameter
when creating the device:
from luma.core.interface.serial import i2c
from luma.core.render import canvas
from luma.oled.device import ssd1306, ssd1325, ssd1331, sh1106
from time import sleep
serial = i2c(port=1, address=0x3C)
device = ssd1306(serial, rotate=1)
# Box and text rendered in portrait mode
with canvas(device) as draw:
draw.rectangle(device.bounding_box, outline="white", fill="black")
draw.text((10, 40), "Hello World", fill="white")
sleep(10)
N should be a value of 0, 1, 2 or 3 only, where 0 is no rotation, 1 is rotate 90° clockwise, 2 is 180° rotation and 3 represents 270° rotation.
The device.size
, device.width
and device.height
properties reflect
the rotated dimensions rather than the physical dimensions.
Examples
After installing the library see the luma.examples repository. Details of how to run the examples is shown in the example repo’s README.