Hi
I thought rather than monitor the Bell output to signal the alarm is triggered I would monitor the Strobe output instead. Reason being that the Bell output is only active when the Bell is actually active, and has a cut-off timer set for x-minutes. The Strobe output however stays active if triggered until the panel is reset. This I thought would be better if I was checking in remotely and requested a Status update. Testing Strobe rather than Bell would inform if the alarm had triggered.
All seemed well however checking the databases I saw I was getting a "Triggered" alert too when Set (quickly clearing), and I would get a transient alert via MQTT too.
Strange I thought and went about investigating. Initial thoughts were perhaps an inducement in the cable as the wires are consecutive. Note I am using a simple resistor based level shifter on the Strobe / Set+ wires to safely interface with the WROOM-32.
Connecting a scope soon showed the problem. Set+ (on Ch1) goes from 0v to 12v when set and I used this as the trigger, capturing Strobe on Ch2. Ideally Strobe would remain at 12v. It didn't. It dropped to zero volts and remained there for six seconds before returning to 12v. My Tektronix Scopemeter may be old but it's still good
This completely ruled out any inducements / bounce or anything along those lines as it was clear the panel itself was doing this. I had forgotten that the default Strobe setting on this panel is to trigger for six seconds upon set, as a visual indication of such. A quick change to the panel programming resolved.
Next is to update to include QoS when sending MQTT messages and it can be put aside until the next update / upgrade. It is quite interesting looking at my captured activity and see that last night I must have been really tired as it didn't log any movement for around seven hours. Other nights it was detecting me every ninety minutes or so as I moved in my sleep.
Regards
