ZigBee Green Power Commissioning

We will discuss ZigBee Green Power commissioning in this post, but first I will do a retrospective.

Retrospective

If you know ZigBee Green Power, or else you have read my previous post , you should have the idea of how a GPD (Green Power Device) differs from traditional ZigBee devices. Also, you should know that ZigBee devices need to act as GPP or GPS to work together with GPDs. Currently, we can implement GPP / GPS by Green Power Infrastructure Devices. Specifically proxy basic, combo basic and commissioning tool are three certifiable devices by to-date specification.

There are three important tables within GPP / GPS. They are: proxy table, sink table and translation table. Proxy table and sink table contribute to GPDF forwarding, while translation table contributes to GPDF execution.

GPDF forwarding

We have that one question left: how can we make these tables into the GPP / GPS ?

OK, let us talk a bit about ZigBee Green Power commissioning.

Green Power Commissioning Process

One should keep in mind: the commissioning process is designed for facilitating the ultra-low nature of GPDs.

Some GPDs are battery-less based on energy-harvesting technologies, so they can only transmit, and they cannot store network information.

There comes the uni-directional Green Power commissioning.

Some GPDs uses battery, so they can be more advanced in functions. For example, they can both transmit and receive, and they can keep network information.

There comes the bi-directional Green Power commissioning.

Green Power Commissioning: uni-directional

First of all, GPS enters Green Power commissioning state.

Next, GPS tells GPPs to enter Green Power commissioning state.

Then the Green Power device broadcasts commissioning frames on a specific channel. This is often triggered by user, like pressing the buttons, etc. However the device knows nothing about the ZigBee network so it is just a try. If this is by coincidence the right channel, fine this very data frame is transferred by Green Power proxies to Green Power sink.

If not lucky, maybe user pushes again and the Green Power devices broadcasts same message, but on a different radio channel.

Traversing all ZigBee channels, finally ZigBee devices knows this Green Power device, by checking the commissioning information it sends.

That is it. Simple and direct.

Green Power Commissioning: bi-directional

First of all, GPS enters Green Power commissioning state.

Next, GPS tells GPPs to enter Green Power commissioning state.

Then the Green Power device broadcasts a data data frame asking for ZigBee operating channel. This is often triggered by user, like pressing some button, etc. However the device knows nothing about the ZigBee network so it sends it on some guessed channel. It is after all just a try. If this is by coincidence the right channel, fine this very data frame is transferred by Green Power proxies to Green Power sink.

Upon reception of the channel request, Green Power sink replies the ZigBee operating channel, which may or may not through Green Power proxies to tell the Green Power device.

Note it is tricky here.  Because the Green Power device is quite power-limited, it opens radio receiver for a very short window after each “channel request”, and then switches to next ZigBee channel. Thus in every channel request message, the Green Power device also tells the next ZigBee channel it will then open for receiving.

So the Green Power proxy or Green Power sink itself has to talk with Green Power device in a ZigBee channel different from the ZigBee operating channel. There is a channel switch here: first switch to Green Power receiver channel, then switch back to ZigBee operating channel.

Temp Master

Who to take the responsibility of channel switching and communicating with Green Power device?  The temp master.

Look from Green Power device, temp master is the master it can talk with, but only temporarily.

Look from Green Power sink, temp master is the Green Power proxy it appoints, but sometimes can be sink itself.

Temp master(s) can be one, or multiple. Increasing number of temp masters will improve reliability of communication with Green Power device, but should be designed carefully to avoid conflict because GPDF is always sent without conflict detection.

Green Power Commissioning: bi-directional – continued

Now Green Power devices knows which channel ZigBee operates on. It continues to send out GP commissioning frame.

GP commissioning frame reaches sink, and the sink replies. Upon reception the GP commissioning reply message, Green Power device knows it is OK. So it sends the last message, which is GP success.

The sink receives GP success message and knows everything is good, thus ends the commissioning process.

Wait, wait ….

Hey, is the GP commissioning process completed?

No, there is one thing missing.

TABLES!

Remember?

The Green Power sink can build up GP sink table during the GP commissioning process, but it also needs to update all those Green Power proxies, with the right Green Power proxy table, otherwise…

No Green Power proxy will transport for this Green Power Device.

The Green Power proxy table is often updated by GP Paring command.

Then we are good.

Another table

After Green Power commissioning process, the Green Power sink can receive commands from Green Power device. But the command is different from ZCL, which ZigBee devices normally talk in.

A method to define Green Power translation table needs to be developed, or hard-coded in the sink (maybe), otherwise the puzzle is still incomplete.

Perhaps the Green Power sink can support Update Translation Table command defined in Green Power cluster specification, or use private methods.

More

To know more, feel free to check the slides I made 🙂

ZigBee Green Power Commissioning Slides