Hi!

Given the fact that most of the ZWave protocol has been open-sourced, would it be feasible to implement the stack into the Wisper Node and join WN devices to a existing ZWave network?

On the other hand, if I use 868Mhz WNodes which do not implement ZWave stack, will WN devices and ZWave-based devices interfere each other?

Thanks in avance

Hi jrartamendi,

Unfortunately the fact of both transceivers working in the same frequency doesn't mean they can talk to each other. The RFM69 (or more generic speaking the Semtech SX1231) has it's own way to modulate data over the selected frequency, as well they implement it's own package framing. On the same situation, Z-Wave specify how this communication can happen and it's in a different way.

The approach in this case is to use/build a Z-wave router/gateway, where for example, you have an Whisper Node connected to a Z-Wave device or module where you can forward messages from one side to another.

Hi again.

I understand then that this implies:
1) The WNode won't be able to directly communicate with legacy ZWave controllers neither being able to act as a routing node for other ZWave legacy devices.
2) Hopefully, as a side-effect of not sharing the same radio layer, it will not adversely affect current legacy ZWave devices.

Am I right?

Nevertheless, does WNode have enough resources to implement the rest of the ZWave stack (MAC layer, network layer, routing layer, etc...)?

I already have a ZWave network controlled by a Raspberry PI which could happily act as a bridge (as it already is capable of doing so with zigbee and other 433 devices).
What I personally like about ZWave is the routing/meshing part, and being able to have a ZWave network of Whisper Devices would be priceless!
I don't mind having 2 separated ZWave-based network, but having the WNodes running their own ZWave-like network.

Regards

Hi again jrartamendi,

Manchester
I don't have experience using the RFM69 (or SX1231) with Manchester encoding (not modulation). I normally use the RadioHead library to access the hardware and I'm not sure if the Manchester encoding is implemented on the library. Saying that you should be able to change it directly on the RFM69 Registers, but again this would only change the bit encoding, you still need to have the same frame format, frequency and radio modulation to be able to talk with another device.

Not Compatible
I haven't spend much time researching but I never see any other user being able to talk with ZWave devices using a RFM69 radio.

Side-effect
It's important to understand that if both radios, ZWave and RFM69, are transmitting on the same frequency, they can cause interference to each other. The fact the can't talk to each other does not exclude the fact both devices will try to "talk" the same spectrum.

Saying that, you can easily change the RFM69 frequency, you normally have a wide range of options. For the 868MHz modules you can basically chose a frequency from 862MHz to 890MHz, as well the frequency bandwidth.

If you have some ZWave devices, try to get the exactly frequency they run and the bandwidth... to avoid interference just move up or down - make sure you stay within the legal frequencies in your country.

Network/Mesh
It'll all depends on your code. You might not be able to replicate exactly how a ZWave network works but you can implement any kind of code to handle packages and route it as you wish. Have a look on the RadioHead library Managers: Router and Mesh (http://www.airspayce.com/mikem/arduino/ ... index.html).

I personally prefer to use simple topology, specially because the RFM69s have an excellent range and normally don't need routing or meshing, so a central base station working as gateway to another network or to the Internet via a RPI is enough. But yes, you might have situations where you need to go over an obstacle like a big hill and a router linking both sides on the hill would be the only solution.

The only other approach I normally recommend is to use "pooling" for low-power devices. Those devices that can't spend much time waiting for messages to preserve battery. The pooling can be linear, random or controlled by a master. Again, it'll depend on the solution to define the best approach.

Thanks for such a comprehensive response

The interference part is maybe the most scaring issue in case I don't manage to implement the ZWave layer, and I was doubting between buying the 433 or the 868 versions.
Nevertheless, seeing that it is at least theorethically possible, I think I'll get the 868 versions and try to ZWave-lize the WNodes.

It probably won't be easy, but hey sure it will be fun!

Saludos!