oled_i2c.py
The 128x64 SSD1306 OLED wires to the I2C bus (GPIO2/GPIO3, pins 3 and 5) and boots with a command sequence. The script brings the bus up, clears the framebuffer, then hands over. On the model-b-rev2, enable I2C in raspi-config or config.txt first.
Hardware
A Raspberry Pi Model B revision 2 (BCM2835, 26-pin GPIO header, Ethernet/USB ports moved to the board edge). One 4-pin SSD1306 I2C OLED module, dupont wires.
Wiring
VCC to 3.3 V, GND to GND, SDA to GPIO2 (pin 3), SCL to GPIO3 (pin 5). The P1 26-pin header groups these pins at the corner.
How it works
smbus writes control byte 0x00 (command) or 0x40 (data) then payload bytes to address 0x3C; the sequence sets pump charge, contrast and scan.
Running it
Copy the script to the board (scp or USB stick), then run it with python3 (or bash). On Raspbian, install gpiozero with sudo apt install python3-gpiozero. The full 26-pin pinout is in the official Raspberry Pi schematic.
Variants
Use luma.oled for text and fonts; two displays via a TCA9548A multiplexer. Revision 2: a clean 5 V supply is required; brown-outs distort sensor readings.
oled_i2c.py
# oled_i2c.py — affiche texte et courbe sur OLED SSD1306 en I2C.
# Deps: sudo apt install python3-smbus i2c-tools (activer i2c_arm)
import time
import smbus
ADDR = 0x3C
bus = smbus.SMBus(1)
def cmd(c):
bus.write_byte_data(ADDR, 0x00, c)
def data(buf):
bus.write_i2c_block_data(ADDR, 0x40, buf)
for c in [0xAE, 0xD5, 0x80, 0xA8, 0x3F, 0xD3, 0x00, 0x40, 0x8D, 0x14,
0xA1, 0xC8, 0xDA, 0x12, 0x81, 0xFF, 0xD9, 0xF1, 0xDB, 0x40,
0xA4, 0xA6, 0xAF]:
cmd(c)
data([0xF0] * 1024) # efface le framebuffer 128x64
print("OLED initialise, i2cdetect -y 1 pour verifier")