Ra-02 LoRa module (SX1278, 433 MHz)
Ai-Thinker Ra-02 · Semtech SX1278 LoRa transceiver · 410–525 MHz (433 MHz) · up to +20 dBm · SPI (NSS, SCK, MOSI, MISO) and DIO0 for the packet interrupt · 3.3 V only (1.8–3.7 V; 5 V destroys it)
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Pins
- GND
- NSS
- MOSI
- MISO
- SCK
- DIO5
- DIO4
- GND
- GND
- GND
- 3.3V
- RST
- DIO0
- DIO1
- DIO2
- DIO3
What it is
The Ra-02 is Ai-Thinker's LoRa radio module, built around the Semtech SX1278 for the 433 MHz band. Here it sits on a blue adapter with two 8-pin rows. It talks to the microcontroller over SPI (NSS, SCK, MOSI and MISO) and raises DIO0 when a packet has been sent or received. LoRa trades speed for range: a few kilometres at SF7, and more at SF12 at a much slower data rate.
What to check before you buy or wire it
- 3.3 V only: feed the 3.3V pin from the board's 3.3 V output, never 5 V.
- ESP32 wiring with LoRa.h: SCK 18, MISO 19, MOSI 23, NSS 5, RST 14, DIO0 2, then LoRa.setPins(5, 14, 2) and LoRa.begin(433E6).
- Both radios need the same frequency, spreading factor, bandwidth and sync word. Always connect an antenna before transmitting.
Common mistakes
- Calling LoRa.begin(915E6) or LoRa.begin(868E6) on a Ra-02. The SX1278 cannot tune there; those bands need an SX1276 module (Ra-01H, RFM95W).
- Using onReceive() without wiring DIO0: the callback never runs.
- Powering it from 5 V.
Where it is used
Long-range sensor links: farm, water-tank and weather nodes, and gate or mailbox alerts several kilometres from the house without Wi-Fi.