| LoRa (SX1278, e.g. Ra-02) | HC-12 (Si4463) | nRF24L01+ | |
|---|---|---|---|
| Band | 433 MHz (SX1276 modules cover 865–867 MHz) | 433.4–473 MHz | 2.4 GHz |
| Interface | SPI | UART (plain serial) | SPI |
| Data rate | About 0.3–37.5 kbps | Air rate 5–236 kbps | 250 kbps, 1 or 2 Mbps |
| Range (line of sight, good antennas) | Several km | Up to about 1 km at the slowest setting (seller figure) | Tens of metres; a few hundred with PA+LNA versions |
| Max transmit power | +20 dBm | +20 dBm | 0 dBm (more with PA+LNA) |
| Supply | 3.3 V only (1.8–3.7 V) | 3.2–5.5 V | 1.9–3.6 V (inputs tolerate 5 V) |
| Typical price in India | ₹350–600 | ₹250–450 | ₹80–150 (₹250–400 PA+LNA) |
When Wi-Fi doesn’t reach — a farm pump 500 m away, a tank on the neighbour’s roof, a weather station in a field — you need a dedicated radio. These three are the common choices. Figures are from the Semtech, Silicon Labs and Nordic datasheets and HC-12 seller documentation; real range depends heavily on antennas, height and obstacles.
LoRa (SX1278 / SX1276): the long-range one
- Trades speed for range: slow data rates, but kilometres line of sight with simple antennas.
- Perfect for small, infrequent messages — a tank level, a soil reading, “pump ON” — every few seconds or minutes.
- Talks SPI and needs a library (e.g. LoRa by Sandeep Mistry). 3.3 V only.
- Never transmit without an antenna attached — it can damage the RF stage.
Component: SX1278 LoRa. Project: LoRa weather node.
HC-12: the easiest
- A serial cable that happens to be wireless. Whatever you
Serial.print()into one comes out of the other. No library. - Configured with AT commands (channel, power, speed) by pulling its SET pin LOW.
- Works on 5 V and 3.3 V boards.
- Good for a few hundred metres to around a kilometre in open ground at the slowest setting.
nRF24L01+: fast and cheap, short range
- Much higher data rates — joysticks, RC cars, sensor networks inside a house.
- 2.4 GHz walls and bodies absorb more, and Wi-Fi shares the band.
- The #1 problem is power: it needs a clean 3.3 V supply with a 10–100 µF capacitor right at its pins. The PA+LNA version needs even more current than many boards’ 3.3 V pin can give.
Component: nRF24L01. Not talking? nRF24L01 fix.
Licence-free bands in India
India’s licence-exempt bands for low-power devices include 2.4–2.4835 GHz and 865–867 MHz (the band LoRaWAN uses here, as “IN865”). 433 MHz modules are widely sold; keep power low and check the current WPC (Wireless Planning & Coordination) notifications before deploying anything permanent.
Antennas matter more than the module
The bare spring or wire antennas in kits are a compromise. A proper antenna tuned to the band, mounted high with clear line of sight, can multiply range many times over. On a rooftop, height beats transmit power.
Verdict
| Project | Pick |
|---|---|
| Farm, borewell or tank far away; small messages | LoRa |
| Simple point-to-point serial link, minimal code | HC-12 |
| RC car, joystick, fast data inside a building | nRF24L01+ |