At the beginning of the year, when I sent off the Raspberry Pi 802.15.4 Radio design to Smart Prototyping to have the PCBs manufactured, I also sent off the design for the second Myha home automation device, a six channel LED dimmer that’s intended to control my bathroom light. Unfortunately this design wasn’t quite as successful as the radio interface. It works well enough that I can still use it, but more through luck than anything else.
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Shortly after creating the Contiki/Zigbit home automation proof of concept over Christmas, I laid out a 802.15.4 radio interface PCB for the Raspberry Pi and sent it off to Smart Prototyping for manufacture. With this interface and the 6lbr router software I can turn a Raspberry Pi into a nice small, self contained Ethernet to 802.15.4 border router, which will form the heart of my new home automation system.
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As I’ve been making more custom automation devices, I’ve come to the realisation that I don’t actually have to be restricted by the limitations of the Rako protocol. I could start again from scratch with my own custom protocol and have no restrictions at all.
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This is my MQTT client library for Contiki.
It is completely asynchronous, starting a new process to handle communication with the message broker. It supports subscribing, publishing, authentication, will messages, keep alive pings and all three QoS levels. In short, it should be a fully functional client, though some areas haven’t been well tested yet.

See the example below for usage.
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Years ago, after running out of breadboard space yet again, I reimplemented the ZM1 6502 computer in a Xilinx Spartan-3AN FPGA on a Spartan-3 Starter Kit board.
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Now that I’ve reversed engineered the Rako protocol, I decided to redesign my touch switch controller so that it transmits Rako commands directly, rather than going via a bank of relays and an official Rako radio module. As the picture above shows, this results in a much smaller and simpler device, and also gives me a lot more flexibility in how the controller can interact with the lights.
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RAKO Protocol Sniffer Wiring

Following on from the previous post¬†where I described the RAKO wireless protocol, I’ve created a sniffer that listens for RAKO messages and dumps them to a serial terminal. The sniffer was created simply by connecting an RRFQ1 receiver module to an Arduino as shown in the image above and uploading the sketch which can be downloaded from here.
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Sniffing RAKO Traffic

The more RAKO devices I add to my house, the more I’ve been running into annoying limitations and strange design decisions. Previously I’ve had to create a duplicate command filter for the RAKO DALI bridge due to its assumption that it will be the only controller on the DALI bus. Most recently I was amazed to discover that their three channel LED controller (RLED90-3DCV) doesn’t support dim-up and dim-down commands, instead it reuses these command to go into a colour cycling mode. This makes it useless for controlling my bathroom light and I’d need to use six single channel controllers at ¬£100 each instead.

So, I thought I’d have a go at reverse engineering their protocol. Then I can create my own compatible devices that do exactly what I want and cost a whole lot less.
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Instead of having a normal light switch in my new bathroom I wanted to have a touch switch hidden behind the wall tiles so that the light could be turned on and off by simply touching a tile, and as with all the other lights in the house, I wanted it to integrate with the Rako home automation system I’m using.
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I’ve seen lots of clones of the Philips Ambilight system that extend a TV picture out onto the surrounding walls by shining coloured LEDs out from the back of the TV. I wanted to do the same with my TV but all the clones out there seemed to be software based, requiring a PC to be producing the TV picture which they then grab frames from, analyse to get the light colours and drive the lights. My TV picture comes from MythTV, so I already have the PC running permanently, but I was worried that the extra load might cause problems when watching blu ray rips. I also wanted to have a lot of LEDs and I didn’t want the lag that is often seen between the TV picture and the LED output.

So I thought I’d try making a completely hardware based Ambilight clone that directly takes in a 1080p HDMI signal.

Click here to jump to the demo videos.
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