RFM12B Linux Kernel Module development

If you’ve read any of my previous posts on the topic I’m trying to get OOK, FSK and potentially PPM (Differential Pulse Position Modulation) working in the Linux kernel with the HopeRF RFM12B adapter. This is mostly for ARM SBC/SoC type situations like the RaspberryPi or beaglebone.RFM12B

The intention here is to allow you to easily intercept, and transmit consumer wireless signals on the 434/868 MHz bands. There are existing ways to do this. However they all appear to depend on the Jeenode or at least an atmega chip running JeeLib.

I want to remove the dependency on the atmega, and yet still exploit the RFM12B to provide OOK/FSK transmission. Right now I’m adapting the existing RFM12B-Linux module to allow sending and receiving OOK signals, I’m also adding in the code to interact with specific defined devices. So far my thoughts are that it shouldn’t be too hard to have drivers for multiple devices in the module.

I thought best to do a link dump of everything that is currently important to this endeavour;

After merging someone else’s OOK sending efforts. I’m not too sure that listening for OOK and FSK is really important. After all an SDR can happily listen across the frequencies and decode the signals.

I unfortunately get very little time to work on this, or other projects on this blog but try to keep it updated with my experiments from time to time. Once I have my Salus under control I plan to release the branch on github. Until then I get a little time here and there to experiment. My latest outcomes have been hampered by insufficient power to my Pi3. There have also been some issues with transmitting on the 868 band.

 

OWL CM160 Energy Monitor with RTL-SDR

OWL CM160I have an Owl energy monitor model CM160, which has been mostly just acting as a real time monitor. In order to really USE the device I’m going to need to connect it to one of my running computers. At first I was using Eagle OWL on github. However it requires me keeping the LCD receiver and I want to eventually get rid of that, mostly because the only useful thing about it, the thermometer isn’t accessible over USB.

I decided that I should start experimenting around the 434MHz band with my SDR’s and see what I could come up with. Continue reading →