The chips
- SX1261 / SX1262 / SX1268 (SX126x): sub-GHz LoRa, LR-FHSS and (G)FSK. SX1261 transmits up to +15 dBm, SX1262 and SX1268 up to +22 dBm. SX1268 is the China-band part (410 to 810 MHz). Semtech quotes sensitivity down to -148 dBm, a 170 dB maximum link budget (SX1262/68), and an active receive current of about 4.2 to 4.6 mA (the page gives both figures). Pros: low receive current and high power; it is the radio on the Heltec V3/V4 and RAK4631 below. Cons: LoRa tops out at 62.5 kbps, and you must pick the right band variant.
- SX1276 / 77 / 78 / 79 (SX127x): the older family. LoRa plus FSK, GFSK, MSK, GMSK and OOK, bit rates up to 300 kbps, +20 dBm or +14 dBm PA, receive current 9.9 mA. SX1276 covers 137 to 1020 MHz; SX1278 covers 137 to 525 MHz (so 433 MHz, not 915 MHz). Pros: OOK mode, long-established library support (see the open source thread). Cons: roughly double the receive current of the SX126x. I could not find Semtech pages for the SX1277/79 individually.
- LLCC68: Semtech's "LoRa Smart Home" part, pin-to-pin compatible with the SX1262, +22 dBm. 151 dB maximum link budget and sensitivity down to -129 dBm. LoRaWAN data rates listed are SF7 to SF9 at 125 kHz, SF7 to SF10 at 250 kHz and SF7 to SF11 at 500 kHz. Pros: same pinout and receive current as the SX1262. Cons: no SF12 at 125 kHz, so less range at the slowest settings, and check your firmware lists it.
- SX1280 / SX1281: 2.4 GHz. LoRa, FLRC and (G)FSK, sensitivity down to -132 dBm, +12.5 dBm PA, BLE PHY compatibility. The SX1280 adds a ranging (time-of-flight) engine; the SX1281 does not. Pros: worldwide band. Cons: same band as Wi-Fi, Bluetooth and Zigbee, and Semtech's -132 dBm is well short of the sub-GHz parts' -148 dBm.
- LR1110 / LR1120 / LR1121 (LoRa Edge): LR1110 does sub-GHz LoRa/(G)FSK/LR-FHSS plus low-power GNSS (GPS/BeiDou) scanning and passive Wi-Fi scanning for geolocation, with a hardware crypto engine. The LR1120 adds 2.4 GHz and S-band. The LR1121 adds 2.4 GHz plus S-band and L-band, and its feature list does not include the GNSS/Wi-Fi scanner. Pros: one chip for sub-GHz, 2.4 GHz and satellite-band LoRa, and low-power asset tracking. Cons: Semtech's geolocation relies on a cloud solver, and you should check your firmware supports the chip.
- STM32WL (SoC): ST puts an MCU and radio in one chip. STM32WL5x/Ex has a LoRa-enabled radio (Cortex-M4, dual-core with M0+ on WL5x), stop modes down to 1.07 uA, radio down to 4.82 mA RX and 15 mA TX at 10 dBm (radio only). STM32WL3x is a different line: FSK/OOK-family modulations for Sigfox, W-MBUS, mioty and Wi-SUN, no LoRa. Pros: fewer parts, low power, pre-certified STM32WLxM modules exist. Cons: you program an ST MCU instead of the usual ESP32/nRF with your own toolchain.
- HopeRF RFM95W: LoRa module for 868/915 MHz with +20 dBm and (G)FSK per HopeRF (an SX1276-family design). Pros: widely documented. Cons: bare module, so you supply the MCU, antenna and wiring.
- EByte E22-900M22S: SX1262, 850 to 930 MHz, 22 dBm, TCXO per its listing, CE/FCC/RoHS per EByte. The E220-900T22D is an LLCC68 UART module (850.125 to 930.125 MHz, 22 dBm), so it is a serial-in-serial-out radio with no SPI work. Pros: easy to wire up. Cons: the 5 to 7 km claims are the vendor's figures.
- Heltec WiFi LoRa 32 V3: ESP32-S3 plus SX1262, Wi-Fi, BLE, OLED, 21 +/-1 dBm, -134 dBm at SF12/125 kHz, bands 470 to 510 and 863 to 928 MHz. The V4 keeps the pinout, adds a GNSS and solar connector, quotes under 20 uA low-power consumption, and comes in a 28 dBm high-power (863 to 928 MHz) or 22 dBm low-power (433 to 510 MHz) version. Heltec lists both as Meshtastic and LoRaWAN compatible, and the V4 as MeshCore compatible. Pros: all-in-one. Cons: 28 dBm is a lot, so check your local power limit including antenna gain.
- RAK4631 (WisBlock): nRF52840 plus SX1262 in a modular system, Arduino and PlatformIO support, with LoRaWAN and LoRa point-to-point. The RAK4631-R runs the RUI3 firmware instead. RAK3172: STM32WLE5 module driven by AT commands over UART, in standard, -T (TCXO) and -F (extra 512 kB flash) variants. Pros: BLE on the nRF52840, and both are low-power designs.
- Murata Type ABZ (CMWX1ZZABZ): SX1276 plus STM32L, 860 to 930 MHz, up to +18.5 dBm, UART interface, certified for major regions per Murata. Pros: pre-certified. Cons: 128 mA transmit current at the 20 dBm setting.
- LilyGO T-Beam: ESP32 with an SX1276/SX1278 radio and a NEO-6M GPS, in 433/868/915/923 MHz versions. Pros: GPS and battery holder for trackers. Cons: when I looked, every variant on LilyGO's page showed sold out or unavailable, so availability varies. Seeed also sells a XIAO ESP32S3 plus Wio-SX1262 kit for Meshtastic.
- General node or gateway: an SX1262 board in your band. Battery LoRaWAN sensor: RAK3172 (STM32WL). Serial bridge with no radio code: E220/E22 UART modules. GNSS/Wi-Fi tracking: LR1110 hardware. OOK or legacy FSK protocols: SX127x.
Question for the group: which LoRa board or module are you running, and has anyone compared an SX1262 board against an older SX1276 one on the same hill?