Compared to the 2.4 GHz WiFi/Bluetooth radios on the Pi already, these modules

run at 433 or 900 MHz (sub-GHz). You can't send data as fast but you can send

data a lot farther. These packet radios are simpler than WiFi or BLE, you don't

have to associate, pair, scan, or worry about connections. All you do is send

data whenever you like, and any other modules tuned to that same frequency

(and, with the same encryption key) will receive. The receiver can then send a

reply back. The modules do packetization, error correction and can also auto-

retransmit so it's not like you have worry about everything but less power is

wasted on maintaining a link or pairing.

These modules are great for use with other microcontrollers with matching

radios (like say our RadioFruit Feathers), say if you want a sensor node network

or transmit data over a campus or town. The trade off is you need two or more

radios, with matching frequencies.

These radio modules come in four variants (two modulation types and two

frequencies) The RFM69's are easiest to work with, and are well known and

understood. The LoRa radios are exciting and more powerful but also more

expensive.

This is the 900 MHz radio version, which can be used for either 868MHz or

915MHz transmission/reception - the exact radio frequency is determined when

you load the software since it can be tuned around dynamically. These are

+20dBm LoRa packet radios that have a special radio modulation that is not

compatible with the RFM69s but can go much much farther. They can easily go 2

Km line of sight using simple wire antennas, or up to 20Km with directional

antennas and settings tweakings



Packet radio with ready-to-go CircuitPython libraries



Uses the license-free ISM band: "European ISM" @ 868MHz or "American

ISM" @ 915MHz



Use a simple wire antenna or spot for uFL or SMA radio connector



SX1276 LoRa® based module with SPI interface



+5 to +20 dBm up to 100 mW Power Output Capability (power output

selectable in software)



~100mA peak during +20dBm transmit, ~30mA during active radio

listening.