Particle Subscribe

Troubleshooting
1

I can’t figure out why my photon isn’t subscribing. Photon one sends out a publish succesfully and I can see that and its associated data in the dashboard, however, photon two isn’t seeing it. I have the handler taking the data and storing it to a particle variable and my variable was never updating. At first I thought it was how I was converting my strings to a number or something but then I threw in the handler for it to publish its own event so I could troubleshoot if it was even subscribing correctly. It never publishes that event so something is wrong with my subscribe code?!

// the pertinent code
// photon 1

void loop() {
Particle.publish("CurrentTemperature", temperature); // publish to cloud
}

// photon 2
double poolTemp = 0.0;

void setup() {
Particle.subscribe("CurrentTemperature", tempHandler, MY_DEVICES);
Particle.variable("PoolTemp", poolTemp);
}

void loop() {
}

void tempHandler(const char *event, const char *data)
{
poolTemp = atof(data);
Particle.publish("hey", "on");
}
2

Your publish statement should include PRIVATE. Hopefully, you have some delay in there so you're not publishing every millisecond or so.

Particle.publish("CurrentTemperature", temperature, PRIVATE);

Also, note this info from the docs,

NOTE 2: Particle.publish() and the Particle.subscribe() handler(s) share the same buffer. As such, calling Particle.publish() within a Particle.subscribe() handler will wipe the subscribe buffer! In these cases, copying the subscribe buffer's content to a separate char buffer prior to calling Particle.publish() is recommended.

1 Like
3

Yeah the code has lots of other stuff in there. Actually it only publishes once every four hours. I see it come through in the dashboard but my subscribe wouldn’t work. Okay so with that note maybe my subscribe was working but maybe I’m not handling the data correctly?

4

Hey thanks adding private made that work! Thanks :slight_smile: I knew I was close! Are we not able to get data from a public publish? I'm just confused why that worked I racked my brain yesterday trying to fifure this out!