ESPGeiger OLED Displays
ESPGeiger supports cheap, widely-available I2C OLED panels for live readout of CPM, μSv/h, history graphs, and status. A small SSD1306 module slotted into an ESP8266 build adds a complete on-device UI for around $3-5.
Supported chips
Set the chip type from Config → Display → Display Type (or build flag -DOLED_TYPE=N). All three options share the same 128×64 pixel resolution and I2C interface; they differ only in the panel driver IC.
| ID | Chip | Common form factor | Notes |
|---|---|---|---|
0 | SSD1306 | 0.96” 128×64 | Default. The cheapest and most common. Tiny but very readable. |
1 | SH1106 | 1.3” 128×64 | Larger panel, slightly nicer pixels. Bus address and command set differ subtly from SSD1306 - pick this if you bought a “1.3 inch OLED” and the screen looks garbled with the default setting. |
2 | SSD1309 | 2.42” 128×64 | Big, clearly readable across a room. Less common, slightly more expensive. Same protocol as SSD1306 - the firmware drives it the same way. |
If a module arrives and the display looks wrong (wrong characters, half the screen missing, snow), try the other chip IDs - it’s the most common “this OLED doesn’t work” cause.
Connection
Four pins: VCC, GND, SCL, SDA. The default I2C pin assignment for nodemcuv2-based ESP8266 builds is SDA = GPIO 4 (D2), SCL = GPIO 5 (D1). These are configurable per build via -DOLED_SDA=N/-DOLED_SCL=N build flags, and most builds also expose them as runtime prefs on the Config page (the exception is fixed-hardware builds like espgeigerhw, where the pins are blocked).
Power: 3.3 V (most modules work with either 3.3 V or 5 V VCC, since they have onboard regulators; but 3.3 V is safer and matches the ESP).
Buying
Search terms that get you the right thing:
- 0.96” I2C OLED 128x64 SSD1306 - the default. White, blue, or yellow/blue dual-colour variants all work.
- 1.3” I2C OLED 128x64 SH1106 - if you want a bigger screen.
- 2.42” I2C OLED 128x64 SSD1309 - for a really visible readout.
Stay away from SPI modules unless you’re building custom hardware - ESPGeiger’s display driver is I2C-only. Modules with 4 pins (VCC/GND/SCL/SDA) are I2C; 7-pin modules are SPI and won’t work without rewiring.
Disabling
Set display.brightness = 0 to blank the panel without disconnecting it. To remove OLED support entirely from a custom build, omit the -DSSD1306_DISPLAY build flag (see PlatformIO Build Options).