Hey, first real project after blinking LEDs. Our small office is on the 3rd floor and the door intercom buzzer is in the back room, so we miss deliveries all the time. I want an ESP8266 (Wemos D1 mini) to notice when the buzzer rings and tell us.
The buzzer gets 12 V AC when someone presses the button downstairs (measured with my multimeter, 11.8 V AC). I know I can’t just put that on a GPIO lol.
The Hermetry part: I already have the D1 sending temperature to Hermetry over MQTT, so I was going to send {"ring": 1} when it rings. But then how does that become a notification on our phones? Half of us won’t install another app on our own phones. Is there a way to get a push or SMS or something when ring = 1?
Alarm rule on the profile with ring == 1? That’s how we did our lab fridge alerts.
The mobile app brings notifications to phones, for whoever installs it. For the rest it’s the bell in the browser, e-mail, chat apps an admin has connected, or SMS from a flow.
App is a no for most of them. We have a team chat app at work, our admin says there is a plugin for it in the marketplace. So chat would be fine if I can get it to post there!
Hardware first. Use an optocoupler: bridge rectifier (or a PC817 with a reverse diode across the LED), 1 kΩ series resistor, 10 µF across the output so the AC ripple doesn’t show up as 50 pulses a second. Transistor side to D5 with INPUT_PULLUP, so the pin goes LOW while it rings. Debounce in code, send ring: 1 on the falling edge, and ring: 0 when it’s quiet again for 2 s.
Then I’d skip the alarm rule. An alarm has a lifecycle (open, acknowledge, clear) and you’d have alarms piling up for every courier. A Rules card rule fits better:
When: A value changes, device "intercom-d1", value "ring", becomes 1
Then: Tell people [x] Members
Message: "Someone is at the street door"
Members get it in the bell, by push where they’ve set it up (the app, or a browser with push on), and in every chat app they linked under My Profile > Chat apps. So once your admin connects the platform each person links their own account and that’s your phone ping, app or not. Rules card recipients never get e-mail or SMS, for SMS you’d need a flow with a Notify block and phone numbers.
One thing to know: the same notice to the same person is held back for a 10-minute cooldown. Fine for a doorbell mostly, but if two couriers come within 10 minutes the second one only shows up as “(+1)” on the next one. Details: Notifications from rules and flows.
IT WORKS. Built the opto circuit on perfboard, first version without the capacitor gave me like 40 rings per press haha, added the 10 µF and it’s clean. Admin connected our chat platform, I linked my account, and now “Someone is at the street door” pops up on my phone about 2 seconds after the button. Thanks Lee!
fair, an alarm per courier would have been silly. stealing the opto circuit for our lab door.
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