Open/Close sensor doesn't register open/close in correct order

[JDRoberts]

@garyd9

Huh? I’m not sure what you’re responding to, but you quoted me suggesting that v2 will timestamp events at the hub before they are sent to a server (with the added implication that it wouldn’t matter as much as the v2 hub should be handling the processing itself.)

I’m not sure how that relates to bluetooth of any flavor.

It relates because you have to get the status messages from the devices to the hub before they can be time stamped. And action requests at the hub, time stamped or not, still have to get back to the individual devices to be performed.

currently the network topologies that ST mostly uses between the devices and the hub are both mesh–zigbee and zwave. Mesh networks just aren’t designed for situations that require sequencing events in a specific order. So the hub time stamping stuff that’s coming to or from devices via zigbee or zwave doesn’t solve the problem, because the messages in both directions are bouncing around the network before arriving. The Closed status could still arrive at the hub before the Open status.

A Brief Note About Scheduling in a Mesh Network

Most people are used to thinking of an app as a way to make something happen. You start it, the thing you asked for happens immediately. In a home automation network that relies on a “mesh network,” as SmartThings does, it’s more like sending a text message to someone else asking them to do something when they can. So you aren’t “turning the light on.” Instead, you’re asking the light to turn itself on once it gets your message. The same things can affect this as affect any messaging system. The recipient may not have checked their messages yet. Or they have gotten the message, but be busy doing something else and so haven’t gotten around to acting on it yet. If you send text messages to several people, like “Let’s meet at 7 in front of the movie theatre,” you can’t be sure exactly who …

However, Bluetooth is not usually a mesh network. (Neither is WiFi.) Bluetooth is point to point, two devices talking directly to each other, not passing messages around first.

So IF the v2 hub provides standard Bluetooth support, then it becomes very easy to sequence action requests, including status checks. But only for devices within about 25 to 30 feet of the hub.

The kicker is that Bluetooth mesh has just been announced and approved by the Bluetooth SIG. And the first device available using it will be a smart bulb from Samsung. Bluetooth mesh would let you cover a whole house, just like zigbee or zwave–but at the cost of doing so with a mesh network, not point to point.

Bluetooth Mesh

Samsung is expected to finally bring its Bluetooth mesh bulb (announced at LightfairJune 2014) to market in about a month. This is a tip of the iceberg look at what I believe will be Samsung’s HomeKit alternative. Based on the Bluetooth mesh from CSR: CSR has an interesting history. British chipmaker, nokia’s failing demand hurt them badly a few years ago, Samsung bought them in 2012 to develop chips for their digital camera division. Used the audio chips more, though, they’re in a bunch of Samsung devices. But when Samsung decided to back off digital cameras, they sold CSR again in 2014. Meanwhile, CSR got involved in the Bluetooth SIG on Bluetooth mesh, and they’ve recently released it. A direct competitor to the future zigbee 3.0, it also, not coincidentally, should play very nice…

So maybe the Bluetooth antenna announced for v2 hub is really meant to support a mesh network of Samsung bulbs and similar devices from other manufacturers.

We just don’t know yet.

But traditional Bluetooth represents a network topology where it’s very easy to sequence events. (Events include status notifications from sensors.) Mesh networks by design make it very difficult to sequence individual events without giving up the benefits which are the reasons you deploy mesh in the first place.

(The features of a mesh network: inexpensive, low energy, pretty dumb devices sending very few, very brief messages and a network that doesn’t panic if any particular node is temporarily unavailable. That leads to some important advantages for home automation: Batteries last a long time, devices are relatively cheap and run cool, the network is resilient and uncluttered.)

It’s easy in a mesh network to make things happen at about the same time, but hard to force the exact order.

Point to point Bluetooth, which may arrive with the V2 hub, makes it easy to force an exact order, but only for devices very close together.

So that’s why the V2 hub’s Bluetooth may be relevant for sequencing.

Hope that helps.