OpenBee: an OpenSource Telemetry Module with Xbee footprint

Hi Guys,

As you know, we are working on OpenLRS project since few years and It is an Open Source RC control system with telemetry, I2C and others. Few days before i designed this new boards. It is based on OpenLRS system but there is no 3.3v regulator, PPM or Servo outputs. It is an open Source Telemetry Module with XBee footprint.   And today prototype boards arrived and i populated it for test and passed. Now we are waiting for quality PCB production (15 days).


  • No more buffering problem of Xbee modules. Real time telemetry or control is possible.(10ms latency)
  • Longer Range, lower frequency
  • No networking stack. Everything in the code. You can write a mesh or point to point, everything is possible.
  • Arduino ProMini based boot and Open Source design
  • No Programmers or FTDI cable require. Just put it to USB to XBee adapter and load the firmware over Arduino. 
  • XBee footprint. (Serial pins only)
  • 100mW 400-470mhz RF Module with FHSS and other functions (RFM22B)
  • up to 3 miles range. (The record is 12KM with Nagoya antenna in England)
  • 3.3v design.

My Job List:

  • Open google code page for OpenBee in a few days (
  • Isolate the OpenLRS code's telemetry part.
  • Test it at the field.
  • Add an option for  MAVLink packages (need help!!!)
  • Find project members.
  • Add the code for simulating OpenLRS Transmitter modules. Computer based RC control is possible with OpenLRS Receivers. Joysticks or something like that.  

What are you thinking about OpenBee project?  Is it good or bad idea? 

Thanks for your comments

Views: 8518

Comment by Sandro Benigno on September 18, 2012 at 9:05am

Great one, Melih! The whole goal sounds nice.
About the ~400MHz band:  Did you check the amount of noise coming from the USB port? I'm using a 3DR 900Mhz radio because it is better on that subject. I'm wondering if an Xbee Explorer USB or another adapter would help or make it worse (close an far from the port i.e. with or without a cable).

Comment by Stephen Dwyer on September 18, 2012 at 10:11am

Cool! I designed one almost the same, but with a few extra features (broke out some extra pins, added options for rp-sma, u.fl or wire antennas, added two additional connector options to the end including 6-pin FTDI cable style pinout for use with sparkfun adapters and the like, with reversible rx-tx pins, as well as a 7pin molex picoblade connector for use with paparazzi style connectors, with added pins for hardware flow control, also provided a funny edge connector for ISP and selectable 5V or 3.3V supply with onboard regulator). However, never had the time to make the software robust....maybe if I find time I will try yours!

Comment by Stephen Dwyer on September 18, 2012 at 11:05am

A question, what real throughput are you achieving with that sort of range and latency?

Comment by Andrew Radford on September 18, 2012 at 11:45am
  • Could be a win for UK users as these can run on 459Mhz with little problems
  • Regards the code - maybe a combined effort with the 3DR telem modules? Both are 'smart' transceivers that can be mavlink aware, i.e can drop unnecessary packets when the link gets patchy etc

Comment by Dany Thivierge on September 18, 2012 at 12:09pm

Again I am afraid to ask this... but what will be the "certification" status of this device?
We all know that I cannot sell legally the 3DR Radio as they are not certified to use in Canada and the certification process is costly. Plus as the code is open it is also an issue for certification.
Anyhow, really would like to offer an alternative to Xbee that would be cheaper and even better. We are using 900MHz around here mostly (legally)


Comment by Melih Karakelle on September 18, 2012 at 1:51pm

@Sandro: Actually i didnt check USB noise. We can try and learn the affects. 
We are in contact with HopeRF and using SiLab based modules and SiLab processors since years. RFM22B and HM-TRP using same RF core (Si4432) on the modules. RFM22B is RF core only product but HM-TRP is including a separated 8051 CPU in same plastic package(Si1000) . This is why we are using both for design and production. I think USB affects will be same for both modules.

@Stephen, I didnt understand the question. Can you explain it? my poor English :(

@Andrew, There is no problem for UK 459Mhz. I guess UK has the best RF regulations on the world and range is better than whole world.
I already ported OpenLRS codes to Si1000 processors (same processor with 3DR) and working but they are not flexible like Arduino based systems. This is why i'm pushing OpenBee.  
I'm also planning to releasing this type(below) modules. They are easy to produce and cheaper than OpenBee. And we can upload SiK firmware into the processors and MAVlink works without any problem. But this is not enough "open" hardware. SiLab very poor supporter and if you need an answer for your specific questions there is no community there. Maybe i can release them with very simple telemetry firmware and configuration software.

@Dany, RFM22B is 0-100mW and 400-470mhz configurable modules. also you can configure 200-1000mhz but output drops dramatically. This mean you can configure it for any regulations. And HopeRF producing 315-433-868-915Mhz versions of them. We can produce any version. I will order few hundred units in this weeks, maybe i can buy some 900mhz modules too. 

Comment by Melih Karakelle on September 18, 2012 at 1:54pm

PS: Green PCBs not for selling, they are prototypes.Final products will be RED like our other products.

Comment by Craig Fraser on September 18, 2012 at 3:14pm

I am also interested in this. As per Dany, I'm in Canada and we have different rules. I am a ham too, so I am not prevented from using an uncertified transmitter anyway. What would be good for most other people in Canada (and possibly elsewhere) is if the transmitter's RF module has been certified by some organization acceptable to our government. Not necessarily the whole Tx-end module that you built, but just the RF part of the Tx module if you are buying those pre-made (I'm unclear...). [Similar to how manufacturers use an approved AC wall-wart so they don't have to get their plug-in device certified.] Thanks.

Comment by Stephen Dwyer on September 18, 2012 at 4:18pm

@Melih, I will rephrase (it was a bit archaic...)

I was just wondering how much data you can send in the serial port and receive out the other module's serial port in bytes per second? Can this data rate be maintained bi-directionally?

Comment by Melih Karakelle on September 18, 2012 at 10:40pm

I remember 900mhz RF modules is licence free in Canada. We can build 900mhz version of it.How about 433Mhz band? is it license free too?

Oh yes, now it is clear. 
We are using 50hz (standard PPM) packages, 57600 baud FSK modulation on OpenLRS code and every pack arriving in 4-6ms. (12ms bidirectional) The pack size depends the code. Current pack size is 17 bytes long. 32 bytes is possible. But the range is dropping depends FSK baudrate. For longer range, SiLab are offering 9600 baud. 
Anyway, at the and we got 4800-19200 baud bidirectional telemetry. I guess 9600 is the best for most of XBee users, because this is the maximum baud limit of 900mhz XBee Pro modules. 


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