Building a wireless network node

Since half a year i have laying around some arduino mini pros and some rfm23bp radio modules and this week I have the opportunity to do some hacking and i decided to see if I could come up with some mesh network nodes build from these components. A picture of that rfm23bp module:


Today I started checking if the hardware actually works and set everything up – which to my surprise took way less time than anticipated. So here is the first breadboard setup:

20150413_015In the middle you can see the Arduino Pro Mini running with 3,3V / 8Mhz, the big thing on the right is the power supply and the rf module is connected on the left. On top of the whole setup you can see the serial/usb adaptor to program the controller from a laptop.

After connecting everything i tried running a sample program for the RadioHead library I’m going to use. After programming and monitoring the serial output of the setup I was able to see the debug messages telling me that the rf module is transmitting. So far – so good, but to actually see if it is working I need to build another node that then could receive the messages from the first one to confirm it actually is working – which i could not do today as I never expected to have it up and running in such a short time.

To not be bored and actually see if something comes out of that rf module i asked a colleague to borrow me his rtlsdr DVB-T dongle and installed gnuradio-sdr along with the gr-osmosdr package which then gave me a nice specturm analyzer like tool that would show any radio activity in the defined wavelength. So, after setting that up and starting the tool I hit the reset button on the network node module and instantly had a visible peak showing that it actually transmitted something:

spectrum_analyze_ism_bandTonight I’ll solder some connectors to the second rf module and then will start hacking on some application making use of the nodes. Eventually I’ll create a third node and then could start testing the mesh functionality.


I finished basic communication between two Arduinos using both a RFM23BP module. The result is some simple application that let’s you chat between Arduinos using their serial port as interface. Code and basic documentation are available at and

Here the connection layout between the Arduino Pro and the RFM23BP module:


Building a wireless network node

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