Flame Sensor Not Triggering Setup

[Jordan22xx]

Hey everyone,

I’m trying to integrate this Flame Sensor into my MySensors network, but it’s just not behaving as expected:

Setup Details:
I'm using an Arduino Pro Mini (3.3V) as the gateway node. Sensor powered from 5V. Relay output connected to digital input pin with INPUT_PULLUP, expecting LOW when flame is detected

MySensors sketch includes S_DOOR type for simplicity, just to read ON/OFF state

When the sensor detects flame, the onboard LED lights up and clicking is heard, so the relay is clearly switching. But in my node logs, I only see the relay output toggling occasionally,mostly it stays HIGH (OFF), even when flame is present continuously.

Swapping GPIO pins, wires, and sensors doesn't change the symptom. No change with or without external pull-down.

I've tried testing the relay output manually via Serial Monitor, works fine, reading LOW when flame is near. Using a hardware pull-down resistor on the signal line, still inconsistent. Enabling debug mode in MySensors, doesn’t show any obvious issues with message transmission or state change. Confirmed the node resets after state change (so it isn’t a freeze).

My Questions:
Could the MySensors library be filtering out rapid changes from the sensor relay? Should I use S_BINARY or a custom sensor type instead of S_DOOR? Is there a timing or debounce issue I’m missing with relay switching vs. reading pin state?

Has anyone used a relay-type flame sensor successfully in MySensors? If so, what input handling (pull-up/down, sensor type) have you used?

Would appreciate any pointers or examples to help me get reliable flame detection working!

Thanks in advance,
Jordan

[fsgraz]

@Jordan22xx do you mean via Serial Monitor from the pro mini ? if it works that would exclude hardware issues. do you poll the pin in the loop ? do you use an interrupt pin ?
I would exclude problems with the mysensors library. is the gateway recognized by the controller ? Check if the node is registered and the sensor presentation works.

[OldSurferDude]

You write "...clicking is heard..." Is that a single click or a click click click ...?

After getting the LOW signal, wait a period of time and if it's still low, send the message that there is a flame. Likewise for a HIGH signal.

Perhaps instead of a relay, an opto-isolator?