Created a video about my RF hardware

I played around a little bit with iMovie and created this video showing the hardware devices  I use for this project.

 

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Works (almost) as expected

20130825-133922.jpgThe picture shows the board plugged into GPIO expansion headers of the Raspberry Pi. The question was: Will the “new” hardware work with the “old” software controlling the CC1101 and responsible for receiving the RF messages? Well, only partly. The SPI communication worked directly without any changes neccessary. But, not a single RF message was received by this “new” hardware. The reason is, that the Anaren A1101R08A-EM1 evaluation module uses a 27 MHz crystal osciallator, while the previous hardware and also the RFBee used a 26 MHz crystal oscillator. All my calculations regarding the frequencies (frequency related configuration registers in the CC1101) where of course based on 26 MHz, and had to be recalculated. After having done that, everything worked pretty well.

Message from socket:  1810755110755130C903000849EF -81dBm
Message from socket:  1800A20100A20130C9030008CCD2 -66dBm
Message from socket:  1810755132BC3F10600301FF0171 -82dBm
Message from socket:  1810755132BC3F2309030101F4C0 -82dBm
Message from socket:  1810751A32BC3F315002010098 -79dBm
Message from socket:  1632BC3F0B1F09030008205F -79dBm
Message from socket:  1632B44AE21F09030008574E -73dBm
Message from socket:  1800A1E2FFFFFF10600301FF01F4 -74dBm
Message from socket:  181071F91071F930C9030008CC24 -68dBm
Message from socket:  181071E8FFFFFF23090302083415 -50dBm
Message from socket:  181071E532B44A3150020100CE -80dBm
Message from socket:  1810755132BC3F10600301FF0171 -81dBm
Message from socket:  1800A20132B44A230903010834A9 -66dBm
Message from socket:  1810751A32BC3F2309030101F4F7 -81dBm

New RF Hardware

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CC1101The “new” RF hardware has arrived, ordered from China (Shenzen) online at http://www.aliexpress.com. After 14 days I got two pieces of this module, for about €15 (including shipping). You can see the TI CC1101 in the middle, the antenna and the oscillator. In contrast to the RFBee, this module does not have a uC or a serial interface. It just has the pure pins to control the CC1101: SI, SO (GDO1), SCLK1, CSn, GDO0 and GDO2 and of course the pins for power supply. The next step will be to get it working with the Raspberry Pi’s GPIO. Somehow need to get this fit onto a breadboard.

Raspberry Pi in action

I modified the standard firmware of the RFBee in a way that puts the CC1101 in “asynchronous mode”, and just tunneled the RF data received through the RFBee’s serial interface. Using a XBee Explorer USB, I can receive this serial data over a USB cable on my Raspberry Pi.

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What was missing is a little python script that decodes the messages received “over the air”. Continuously receiving data from the serial port puts a heavy load on the pi’s CPU, but currently this is the easiest solution to receive the RF data without the need to built some custom hardware. But maybe, in the future …