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VeraSecure conversion to AU Frequency

Posted by LiveHouse Automation on

For those who read our previous blog on Australia/New Zealand frequency versions of the new Vera controllers, you may be wondering how the VeraSecure conversion experiment panned out.

Upon receiving the new VeraSecure and pulling the case off, the first obstacle I hit was the VeraSecure uses a different Z-wave module (ZM5202)

Compared to the VeraPlus which uses a ZM5304:

These are not to scale (look at the the main chip size as reference), the ZM5202 is fiendishly small which I didn't discover until I ordered some ZM5202's from Digikey. As it was going to be one serious amount of faffing around to remove the module and replace it, I looked into what the difference is between the AU and non-AU versions of the Z-wave modules.

Disclaimer - I am not an RF Engineer. What follows may contain traces of speculation or ignorance.

From modifying the VeraPlus I already knew the Z-wave chip was frequency programmable. The firmware determines that setting. It's the surrounding components on the PCB that optimise the module for a specific region - the antenna and in particular the band-pass filter. In simple terms this little component blocks out frequencies outside of a certain range so that the transceiver doesn't get exposed to radio noise.

Australia uses 921.4 Mhz. The US uses 908.4 Mhz. Not too far apart really. I did some research into bandpass filters that looked similar to the ones in use on the ZM5202, comparing the graphs of the frequency filtering. For the most part it looked like the Australian "band" that Z-wave operates on would fall just inside the band of the US bandpass filter. Best case a bit of range might be sacrificed. Worse case a lot.

So rather than going straight for the hardware hack, I opted to test the software only modification first and see what results I could get.

The Test

Initial testing was conducted using 2x AU Frequency Aeotec Smart Switches. Started up the VeraSecure, and proceeded to pair the devices while they were all sitting on the workbench. This was successful, as expected. 

I took the switches and plugged them in different locations around the house to test the range. Much to my surprise, the switches operated just fine up to 20m away through 3-4 brick walls. I left them for a couple of days, occasionally testing them for operation, retries, and using Vera's Stress Test function. Everything looked good. Admittedly the range wasn't up to my VeraEdge with antenna mod but that's to be expected.

I decided to go all in and move my entire home over to the VeraSecure. One Z-wave device at a time as I needed to resolve an underlying problem with a previous Z-wave controller shift. It took 4 solid days of pairing and configuring all the logic. 

Yeah, my house might be where Skynet becomes self aware.

The Verdict

It's been more than a month now running full time on the VeraSecure. Other than a new KAS Door Lock that's a bit slow to respond, I can't fault the Z-wave network. To be fair I never tested the KAS on the VeraEdge, and it's in a pretty awkward spot relative to where Vera lives.

The 512MB RAM, and extra CPU core in the VeraSecure makes it pretty snappy and reliable - no odd Luup restarts that I had on the VeraEdge. The only annoyance was default behaviour of the Siren being linked to home modes, and the fact that the VeraSecure has a built in battery - you can't power cycle it unless you open the base and pull out some wires.  

If you've got a large and complicated home automation system with lots of plugins then the VeraSecure is a worthwhile investment. 

If only they were available off the shelf. 

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