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Section 3.5 OLED display

Micropython has built-in support for displaying simple graphics, and there are already libraries to interface with a number of displays. In this section, we'll be using a common OLED display model, the SSD1306.

Subsection 3.5.1 S2 Pico built-in OLED

The Wemos S2 Pico has a built-in OLED display, as well as drivers ready to go. We can use it with the following code:

from s2pico_oled import OLED
from machine import Pin, I2C

i2c = I2C(0, sda=Pin(8), scl=Pin(9)) # Pins 8 and 9 are hard-wired
oled = OLED(i2c, Pin(18)) # Pin 18 is hard-wired to reset the display
oled.test() # Remove this test once you start displaying your own stuff

The MicroPython documentation 1  describes the various functions you can call to control the display:

display.poweroff()     # power off the display, pixels persist in memory
display.poweron()      # power on the display, pixels redrawn
display.contrast(0)    # dim
display.contrast(255)  # bright
display.invert(1)      # display inverted
display.invert(0)      # display normal
display.rotate(True)   # rotate 180 degrees
display.rotate(False)  # rotate 0 degrees         # send your drawing to the display

And there are a set of functions you can use to draw stuff:

display.fill(0)                       # fill entire screen with color=0
display.pixel(0, 10)                  # get pixel at x=0, y=10
display.pixel(0, 10, 1)               # set pixel at x=0, y=10 to color=1
display.hline(0, 8, 4, 1)             # horizontal line x=0, y=8, width=4, color=1
display.vline(0, 8, 4, 1)             # vertical line x=0, y=8, height=4, color=1
display.line(0, 0, 127, 63, 1)        # line from 0,0 to 127,63
display.rect(10, 10, 107, 43, 1)      # rectangle outline 10,10 to 117,53, color=1
display.fill_rect(10, 10, 107, 43, 1) # solid rectangle 10,10 to 117,53, color=1
display.text('Hello World', 0, 0, 1)  # some text at x=0, y=0, color=1

Note that calling these drawing functions sets the values of pixels, but doesn't actually send them to the display. To see the changes, you'll need to call

Subsection 3.5.2 Wiring an external display

Below is a complete code example for an SSD1306 OLED display that you've wired up manually. You'll need to make sure you have the library copied to the ESP32.

# This assumes that you've connected it as follows:
# GND -> GND
# VCC -> 3.3V
# SCL -> D2
# SDA -> D4

from machine import Pin, I2C
import ssd1306
from time import sleep

# Set up the display
i2c = I2C(0, scl=Pin(2), sda=Pin(4))
display = ssd1306.SSD1306_I2C(128, 64, i2c)

# Now show some text on the display
display.fill(0) # First clear the display with 0 (black)
display.text("Hello!", 5, 5) # Draw text located at pixel (5, 5) # Send the pixel data to the display to show it