LoRa radio communication devices for Raspberry Pi - Raspberry Pi

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Need to send data from a Raspberry Pi–based project located beyond your home’s Wi-Fi network range? Sure, you could use a Wi-Fi extender, or a very long Ethernet cable (up to 100m), but there are other, more reliable solutions that we’ll be exploring here.

LoRa is a long-range radio system that can transmit small packets of data at low bit rates (300bps to 50kbps) — ideal for IoT sensors and the like. Its biggest advantage is its resilience to noise and interference, enabling a range of up to 15km (9 miles) in rural areas. LoRa nodes can send data to each other, or you can use a LoRaWAN gateway to receive multiple channels — either an existing one on, say, The Things Network, or your own.

For (much) higher data rates, there’s 4G cellular. We take a look at a couple of add-on solutions here, along with a separate GPS module for ultra-accurate location- and time-stamping.

Warning!

Radio regulations

LoRa uses the ISM (Industrial, Scientific, and Medical) radio bands. Anyone can broadcast here without a licence, but you must adhere to the regional parameters set by local governing bodies (e.g. Ofcom in the UK, FCC in the US, ETSI in Europe). These include limits on radio frequency, duty cycle, and transmission power.

There are also typically strict limitations for transmitting on other radio bands such as FM. Always check the laws for your jurisdiction before proceeding.

SX1262 LoRa Node Module for Raspberry Pi Pico

This Waveshare LoRa module (£14/$19) is based around the SX1262 transceiver, which offers superior power efficiency and slightly longer range than the earlier SX1276. The board features twin female headers, so all you need is a Raspberry Pi Pico equipped with male headers to plug into it. It even extends Raspberry Pi Pico’s pins to the top.

Along with the LoRa module itself, the package includes a bonus 600mAh 3.7V LiPo battery connected to the board’s charging IC, so you’re all set up for remote power.

Note that while The Pi Hut sells the 868MHz-band version of this LoRa module for use in Europe (including the UK) with a ‘stub’ antenna supplied, Waveshare stocks three versions, each tuned to a different frequency — make sure to choose the right one for your region.

While the Waveshare documentation isn’t that easy to follow, there are C/C++ libraries with some code examples to try out — no MicroPython ones, but you could use an existing SX126x library.

Verdict

Superb value for money, includes a LiPo battery and an antenna.

Perpetuo LoRa

With a built-in Raspberry Pi RP2350 microcontroller chip (as used on Raspberry Pi Pico 2), this all-in-one LoRa board (£21/$28) has everything you need to start communicating with a LoRaWAN network gateway. Alternatively, you could use it in a simple peer-to-peer setup with another LoRa node.

Equipped with an Embit EMB-LR1276S LoRa radio module, the Perpetuo operates on the UK/European standard 868MHz carrier frequency using the default firmware, but it can be tweaked to use the 915MHz band. You’ll also need a suitable external RF antenna — it’s vital you connect one before powering up this, or any other, LoRa board, otherwise you may cause damage.

With a low power mode, the Perpetuo is very energy efficient. Power is provided by a LiPo battery (not supplied) that can be recharged via the USB-C port. The latter can be used with an optional solar panel (typically via a voltage regulator) to keep the board running indefinitely when it’s off-grid. A Qwiic/STEMMA QT connector makes it easy to add one or more sensors. In addition, the board has 32 standard pins, including 20 GPIOs.

Verdict

An energy-efficient LoRa node with a handy Qwiic/STEMMA QT port.

LoRa Radio Bonnet with OLED

This LoRa ‘Bonnet’ (£31/$42) can be mounted onto the GPIO header of any standard 40-pin Raspberry Pi computer. While it’s labelled as ‘915MHz’ on the Adafruit site, it can use either the North American/Australian 915MHz ISM band or the European 868MHz band — you just need to make sure you set the correct band for your region in your programs. Fortunately, CircuitPython firmware and libraries make it easier to set up and use than some other boards.

Another bonus is the 128 × 32 OLED screen that can be used to show status messages. There are also three tiny buttons you can use to create a user interface or send test messages.

For the antenna, you can attach one to the U.FL connector on the board, or even just solder a piece of wire to the pad next to it. One slight drawback is that its RFM95W radio module, while reliable and well documented, uses a classic SX1276 LoRa transceiver that isn’t as power efficient as some later...