Multiple Photon InterConnectivity Project - Help Please!

General
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Hi all. I am relatively new to IoT devices and programming but I thought I’d dive head long into a project I’d actually want to get running to learn how to do it. Crazy, I know.

Here is my idea that I have very little idea how to get running.

I want to make a gift for my siblings. These gifts would be an LED connected to a Photon, powered by a wall plug, connected to their various networks, and these lights would all be interconnected. When sibling A activates his light (saying “Hi”), it would turn blue. Then, in response to sibling A activating his light, siblings B, C, and D etc. would have their respective lights activate blue as well in whatever location and network they are located. In response, sibling B could activate their light saying “hi” in return and thus push their selected color onto the other lights, possibly with some pulsating because it was a response to sibling A first saying “hi”.

To start with, I already have two photons, two neopixel rings, and the power supplies for hardware. I have them both wired up and I have loaded simple projects that I have found online to make sure my neopixels are working and wired correctly. Both photons connect to the internet just fine.

Where I am now having problems is how to I tell the photons to look for the “Hi” that another lights are sending? I’m assuming I’d have to program in a publish command and use the cloud to manage sending and receiving the publish commands? Would I also need to add a subscribe function? How then could I set up a return “hi” to the other units? I’ve already spent the better part of a couple days to no avail and am back to the drawing board as it were on my coding. Any info/advice/sarcastic comments are greatly appreciated and welcomed.

I’m sure I’ll have many more questions arise but I feel like this is a good start.

Thanks and I look forward to your help.
Micah

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Publish and subscribe is the way to go.
Photon A publishes “Hi A”, to which Photon B subscribes. In turn, Photon B can publish “hi B”, to which Photon A subscribes.

So you’d end up with publish/subscribe pairs on the relevant devices.
There’s an example in the docs: https://docs.particle.io/guide/getting-started/examples/photon/#the-buddy-system-publish-and-subscribe

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Thanks for your reply @Moors7. So using this example, would I need to set up a pub/sub list for each photon?

I.E. A publishes “Hi” and B, C, D, E, etc. would all be subscribed to it. Then B pubs “Hi” and A, C, D, E… are sub’ed to that pub, etc?

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Yes, that’s the general idea. You can use the same event name for each of your devices in the Particle.publish(), and only change the data – the data argument could contain the name of the sibling that sent it, for instance. This way, each device only needs one Particle.subscribe, to that common event name.

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To further expand on that, not even the full event name needs to be exactly subscribed to, but only the starting part (prefix) of it.
So Particle.subscribe("Hi", hiHandler, MY_DEVICES) would fire for Particle.publish("Hi A!", data, PRIVATE) and for Hi B! just the same as for Himalayas.

So, as another tip is not to use a nondescript event name like Hi but something more creative :wink:

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