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what is the rapidradio?

Isn’t it just beauty?
No, it’s not.
It is beauty and it works!
How cool is that?

rapidradio means the simplest wireless connectivity for your Raspberry Pi.
It’s a half-duplex 2.4GHz transceiver based on the RFM75 module (made by HopeRF). It’s a perfect solution for any kind of home automation, robotics, DIY projects, Arduino-to-Raspberry Pi projects etc.
You will be surprised how much you can reach using rapidradio. So much opportunities and so much fun, because it will work for you both ways – for your projects and for your taste. Enjoy!

Dimensions (L x W x H): 27mm x 21mm x 12mm
Voltage: 1.9V – 3.6V, I/Os are 5V-tolerant
Interface: SPI up to 8MHz
RF features: RF power programmable: -35 .. +5dBm; 2.4000-2.4835 GHz ISM band (83 channels), 4-byte addresses
Speed: max. 2Mbit, but practical usable up/down stream is lower when all CRC, ACK, auto-repeat, etc. options are enabled.
Open area range: ~70m; improved indoor range by rapidradio wire antenna in comparison to the RFM75’s pcb antenna

Raspberry Pi setup

How to set up rapidradio? don’t worry, it’s a child’s play.
Just plug it in to your Raspberry Pi as shown on the pictures below – meaning into the inner pin column, starting from the 6th pin from bottom (true for all Raspberry Pi versions).
Do not forget to switch-off and unplug Raspberry Pi first (just in case).

Raspberry Pi model A/B

Raspberry Pi model A/B

Raspberry Pi model A/B

Raspberry Pi model B+/Raspberry Pi 2

rapidradio pinout

rapidradio pinout

Then get the rapidradio tool. You can download compiled binary here (Raspbian Wheezy) here:


or go to the downloads page

or you can build it from source on your own:

sudo apt-get install autoconf
git clone https://github.com/micas-pro/rapidradio.git
cd rapidradio/raspberrypi
chmod 744 rapidradio_install.sh
sudo make install

now you are ready for a transmission!
start listening using address 0x12345678 and channel 50:

sudo ./rapidradio -l -a=0x12345678 -c=50 > received_file.txt

To stop listening just hit Ctrl+C.

Then on second Raspberry Pi use this command to send a ‚sample_file.txt’ to the listening rapidradio you’ve just set (address 0x12345678 and channel 50):

sudo ./rapidradio -a=0x12345678 -c=50 < sample_file.txt

You’ve just sent a file. A child’s play, wouldn’t you agree?

Note: The channel number and target device address need to match values used on a listening device.


./rapidradio --help

to see all available rapidradio tool options.

Note: ‚sudo’ rights are required to access SPI interface on Raspberry Pi.

Arduino Uno setup

Yes, you can use the rapidradio with your Arduino board too! Detailed description and sketch source files can be found on this page.



frequently asked questions (FAQ)

  1. I plugged the rapidradio into a Raspberry Pi, I see the LED light but it does not work (init error).

    Please double check whether you plug the rapidradio correctly. The LED is directly connected to the CE pin, so if accidentally on that pin there is a high state (+3.3V) then the LED will just shine, but it doesn’t mean the rapidradio works. Init error means that there were no correct communication through the SPI interface between Raspberry Pi and the rapidradio.
  2. I took just one rapidradio and tried to send some data but I’m getting only errors.

    By default the ACK option is turned on, so the sender rapidradio expects to receive ACK packets for every sent packet. If nobody is listening (e.g. a second Raspberry Pi with a rapidradio in listening mode) then default sending will fail because of that.
    The ACK option can be skipped by adding the -nack parameter to the rapidradio command-line tool.
  3. While sending I see ‚error 2′ or ‚error 3′ from time to time, but finally the file is transmitted correctly.

    The air is getting crowded, so from time to time some packets get lost. To keep the whole transmission correct there are two levels of re-transmitting lost packets: hardware level and software level. Hardware level is provided by the RFM75 itself: there are up to 16 auto re-transmissions if no ACK packet is seen. Software level is implemented by the rapidradio library (used by the command-line tool). There is configurable amount of high-level re-transmissions with 100ms intervals, packet numbering to skip doubled packets and notice skipped packets. In short words: the errors are related to the hardware-level only and can be treated as a link quality indicator. If the devices are in range, then the whole transmission should be completed correctly, regardless of the low-level errors for some missing packets.

  4. Is the rapidradio designed to talk to the other rapidradios only?

    No. You can send and receive packets to/from any device using the RFM7x transceiver (RFM70, RFM73, RFM75).
    Apparently it’s even possible to communicate between RFM7x and nRF24L01 transceivers.

3 Comments so far:

  1. Jan Busk pisze:

    Hi! How do I use the usb-rapidradio in ubuntu 15.10?

  2. Jan Busk pisze:

    Hi! When running the line: sudo ./rapidradio -l -a=0x12345678 -c=50 > received_file.txt
    on my raspberry pi 2 with rasbian jessie i got the error message: gt does not exist.

    The solution is to replace &gt with >gt
    sudo rapidradio -l -a=0x12345678 -c=50 >gt recieved_file.txt

    • Jan Busk pisze:

      I was a bit trigger happy with the last comment. :-)

      The line
      sudo rapidradio -l -a=0x12345678 -c=50 >gt received_file.txt
      executes without errors but does make the transceiver stay in listening mode. I starts and shut down immediately.

      I modified the command so it just pipes the output from rapidradio to the text file. The rapidradio transceiver now stays in listening mode.

      sudo rapidradio -l -a=0x12345678 -c=50 >> received_file.txt

      Sending has the same issue. After borrowing my sons rasbperry pi i managed to both send and receive without any trouble.

      I hade to modify the send command as follows:
      sudo ./rapidradio -a=0x12345678 -c=50 < sample_file.txt

      All characters sent was received without errors.

      /Jan B

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