Minimal Build
Edit on GitHubThe smallest possible beacon: ESP32 plus radio and battery, no OLED or GPS, and what you give up for the size.
Minimal Build
Sometimes the mission is: smallest, cheapest, most robust. The minimal build drops the display and the GPS and keeps the core: an ESP32, a radio module, and a battery.
The bill
| Part | Role |
|---|---|
| ESP32 board | Everything |
| E22 / SX1262 module | The radio |
| 18650 cell + TP4056 | Power |
| Antenna | The radiator |
| Two buttons | Mode and select |
Total cost is roughly $14 - $18, about two-thirds of the standard build (see Shopping List).
What you give up
| Feature | Lost |
|---|---|
| OLED | No screen: config by serial or WiFi only |
| GPS | No automatic coordinates: manual entry required |
| Audio | No tone output |
| Status feedback | LED only |
How it works
The minimal beacon still transmits the full payload. Without a display, configuration happens over the serial port or the WiFi config portal (see WiFi Config Portal). Coordinates are entered manually in decimal degrees. The Mode Config flow is identical; only the surface changes.
When it is the right build
- A permanent or semi-fixed beacon at a known location (coordinates entered once)
- A learning or classroom board
- A backup unit that lives in a drawer until needed
- Anywhere size and robustness beat convenience
Build notes
- Without the OLED, the I2C bus is free; leave the pins accessible for diagnostics.
- The two buttons are mandatory: the firmware expects at least MODE and SEL.
- Keep a serial adapter in the kit: it is the only configuration path without a display.
Related pages
- Build Configurations for the comparison
- Standard Build for the full version
- Displayless Build for the middle ground