Thursday, January 24, 2019

Adafruit Radio Bonnets with OLED Display - RFM69 or RFM9X

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The latest Raspberry Pi computers come with WiFi and Bluetooth, and now you can add even more radio options with the Adafruit Radio Bonnets! Upgrade your Raspberry Pi with a radio so it can communicate over very long distances. These bonnets plug right into your Pi and give you long range wireless capabilities to remote nodes that may be battery powered. Or, you can create Internet gateways with ease.

You not only get a radio module, but also a 128x32 OLED display for status messages and three buttons you can use for creating a custom user interface or sending test messages. All of the above is supported with our Python libraries so you can send or receive radio data with other matching modules. With the LoRa Radio Bonnet, you send data to a LoRaWAN gateway, or even set up your own single channel LoRaWAN-to-Internet gateways.

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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 its 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.

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Radio Modules & Frequency Variants

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

  • The first variant is the RFM69 Radio Bonnet. RFM69's are easiest to work with, and are well known and understood. It is available in 433MHz or 900MHz frequency ranges
  • The second variant is the LoRa Radio Bonnet - an exciting and more powerful radio module, but also more expensive. It is available in 433MHz or 900MHz frequency ranges

Here are the four bonnets you can choose from. All radios are sold individually and can only talk to radios of the same part number. E.g. RFM69 900 MHz can only talk to RFM69 900 MHz, LoRa 433 MHz can only talk to LoRa 433, etc.

  1. RFM69 @ 433 MHz - basic packetized FSK/GFSK/MSK/GMSK/OOK radio at 433 MHz for use in Europe ITU 1 license-free ISM, or for amateur use with restrictions (check your local  amateur regulations!)
  2. RFM69 @ 900 MHz - basic packetized FSK/GFSK/MSK/GMSK/OOK radio at 868 or 915 MHz for use in Americas ITU 2 license-free ISM, or for amateur use with restrictions (check your amateur regulations!)
  3. RFM9x @ 433 MHz - LoRa capable radio at 433 MHz for use in Europe ITU 1 license-free ISM, or for amateur use with restrictions (check your local amateur regulations!)
  4. RFM9x @ 900 MHz - LoRa capable radio at 868 or 915 MHz for use in Americas ITU 2 license-free ISM, or for amateur use with restrictions (check your local amateur regulations!)

Please note! The 900 MHz radio version, 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.

The radio modules themselves have the same pinout so the PCB is the same, but the library usage and wiring may vary. All use SPI for interfacing, and there are CircuitPython libraries available for both.

RFM69 Specs

  • SX1231 based module with SPI interface
  • Packet radio with ready-to-go Arduino libraries
  • Uses the license-free ISM bands
  • +13 to +20 dBm up to 100 mW Power Output Capability (power output selectable in software)
  • 50mA (+13 dBm) to 150mA (+20dBm) current draw for transmissions
  • Range of approx. 350 meters, depending on obstructions, frequency, antenna and power output
  • Create multipoint networks with individual node addresses
  • Encrypted packet engine with AES-128

RFM9x Specs

  • SX127x LoRa® based module with SPI interface
  • Packet radio with ready-to-go Arduino libraries
  • Uses the license-free ISM bands
  • +5 to +20 dBm up to 100 mW Power Output Capability (power output selectable in software)
  • ~300uA during full sleep, ~120mA peak during +20dBm transmit, ~40mA during active radio listening.
  • Our initial tests with default library settings: over 1.2mi/2Km line-of-sight with wire quarter-wave antennas. (With setting tweaking and directional antennas, 20Km is possible).

Each bonnet comes fully assembled and ready to go. You can attach an antenna via the uFL connector, or cut and solder on a small piece of wire (any solid or stranded core is fine) in order to create your antenna.

This guide was first published on Jan 23, 2019. It was last updated on 2019-01-23 14:19:14 -0500. This page (Overview) was last updated on Jan 23, 2019.

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