Split – Arduino based RFM22B 433/868/915 MHz wireless module

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Top side of Split RF module

Bottom side of Split RF module. Notice the counter sunk LEDs in the upper left corner.

UPDATE May 15 2013: Split is now available for sale on our website

We’ve been slowly working away on an Arduino based wireless module called “Split” and just got the first real prototypes assembled and working over the last week. The module is based around a Atmega328P and a RFM22B wireless module, so it is kind of like a cross between a Arduino Pro Mini and a RFM22B breadout board.

Specs and Features:

  • Operating voltage: 3.3V
  • Processor: Atmega328P with Arduino bootloader
  • RF Frequency Range: 433MHz, 868MHz, or 915MHz ISM band (depending on version)
  • RF data rate: adjustable from 0.123 to 256kbps
  • RF output power: adjustable from 1 dBm to 20 dBm
  • RF receive sensitivity: -121 dBm
  • Long range up to several Km with proper antennas
  • On board 3.3V regulator
  • PCB Size: 20mm x 38mm
  • All processor IO pins are brought out to header pins
  • Breadboard compatible
  • Programmed with FTDI Pro
  • A user LED and button connected to IO pins
  • Slide switch to allow the DTR signal from the FTDI Pro to be directed to an IO pin to allow programming of a remote Arduino processor

Split RF module connected to a FTDI Pro

There are three main ways we envisioned Split being used:

  1. As a standalone processor with wireless capability.
  2. As a generic wireless UART link with remote DTR control to allow communicating with and programming of a Arduino processor attached to the remote Split module.
  3. As a wireless IO link. Input pins on one end are mapped to output pins on the other end and vice versa.

We’ve done some initial testing with the RF22 library from open.com.au and it seems to work so that covers #1, and we are in the process of writing firmware for #2 and #3.

We are pretty excited about the long range wireless capabilities Split will give to a lot of projects.

Split RF module connected to the Mongoose IMU

User switch and LED at top.

If you are interested in this project, leave some feedback or a comment. Once we know how much interest there is, we can make some better plans for a release date.

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About Cory

Electrical engineer, embedded system developer, PCB designer, amateur machinist.
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24 Responses to Split – Arduino based RFM22B 433/868/915 MHz wireless module

  1. avatar James Coxon says:

    Hey,
    Looks awesome.

    I’m currently using the RFM22B as the transmitter for an ultra lightweight balloon payload. Instead of using the data link I’m doing morse and hellschreiber by turning the unmodulated carrier on and off. While very low tech (especially as the RFM22B can do lots) it does mean that we get very long ranges of about 150miles (helped by good LOS and sensitive receivers)

    Would be interested in this combined breakout board for future payloads.

    James M6JCX

    • avatar Cory says:

      150 miles is incredible. What is the sensitivity of your receiver?

      • avatar James Coxon says:

        Using a Yaesu FT817 with a whip antenna. Its sensitivity is 0.25uV on the 70cm band. Probably could do better if I also used a yagi on the rx end.

        I’ve also got RTTY working as well – planning to launch the payload this weekend – will see if we can get better range!

        James

        • avatar navrac says:

          Blimey James, we seem to be looking at the same things the whole time!

          Now all we need is integrated gps and this would be perfect.

      • avatar Whammy! says:

        You have to remember that balloons are miles up. On the ground expect no more than a couple miles max.

  2. avatar John Scherer says:

    Working on a few projects at our local maker space that will require wireless RF access. Currently using jeenodes but the layout of yours is much more convenient for one of our UAV projects. Would love to get one to test with. Let me know when there available.

    Cheers

    John

  3. avatar luis says:

    Currently using JeeNodes for some home automation. I would be quite interested in extending the range for some urban projects.

  4. avatar mike taylor says:

    Big fan of arduino and RF. When will they be available?

  5. avatar Whammy! says:

    433MHz is in the HAM band right? Does one need to be licensed? Are there limitations to its use?

  6. avatar Whammy! says:

    BTW, very interested. Especially if the price is right!

  7. avatar Andreas Kraeuchi says:

    Woooh cool lite piece of hardware would love to have some of them in a Mesh network with lots of sensors attached!

  8. avatar Joshua Mesilane says:

    Hi,

    Very interested in these modules. Could you drop me an email and let me know how you’re progressing with the project? I’d be very keen for at least a couple of these, as I was looking at doing (more or less) the same thing by building a shield for the Nano board.

    Cheers,
    Josh

  9. Really would like to se a finished product line for this one :)

  10. avatar Wing Wong says:

    Very cool project. Would love to know when it is available and what the cost per unit would be?

  11. avatar Dan says:

    Spec’ing out a project for the 70cm band. Came across this project and I’m very interested. Looks like this would make my life a lot easier. How close to production are they?

  12. Please email me when this beaty is available. Would be very interesting to try with the planned improved version of an UAV variometer project of mine. Especially if the anticipated range is decent. I am currently experimenting with a pair of XBee Pros (900 MHz). Works very well, but the power consumption is rather prohibitive.

  13. avatar Michael says:

    I was thinking about prototyping something similar to this.
    I would be interested in getting a few of these if you make them.
    Please let me know if/when you think you will be ready to sell them?

    • avatar Cory says:

      Thanks for your interest.
      We have the first batch build and ready to sell, we just have a few bugs in the UART link firmware that I would like to fix first. So, I know I’ve said it before, but just a few more days.
      -Cory

  14. avatar Nigel says:

    Are these available now and if so, what is the price?

    Regards,

    Nigel.

  15. avatar Cottsay says:

    So…what is the latest status?
    It’s been a month since the last update…

    –scott

  16. avatar Bruce says:

    I’m keen for a couple of these…have you got the bugs worked out yet?

  17. avatar Steven Chew says:

    I’m looking for arduino-based system for wireless telemetry, with a range of at least 2km in open terrain. I’ve tried the xbee pro, but we are getting only about 250m. Would these rf module be able to handle the range? The tx is from a moving vehicle, approx 40 kmh, so would have to be dipole antennas.

    Are the modules currently available & how much are they?

    thanks,
    Steven

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