The TF-Luna A03 has a 4-wire connector. UART mode is the default; I²C mode can be enabled via configuration command.
Pinout (UART mode, default)
| Pin | Color (typical) | Function |
|---|---|---|
| 1 | Red | VCC (+5 V, ~70 mA) |
| 2 | Black | GND |
| 3 | White | TX → MCU RX |
| 4 | Green | RX ← MCU TX |
Connection notes
- Common ground is mandatory; UART without common GND produces garbage frames.
- 5 V power — TF-Luna doesn’t run on 3.3 V. If your MCU rail is 3.3 V, use a separate 5 V supply for the sensor (and a level shifter on TX if the MCU is 3.3 V tolerant only).
- Shared bus considerations: if multiple TF-Lunas share an MCU, use multiple UARTs rather than software multiplexing — UART resync on every switch isn’t reliable.
Where to go next
- Driver firmware
- TF-Luna hub
- SG90 sweep design — TF-Luna + servo specifics