Servo controlled deadbolt

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EmilyPearson
Posts: 10
Joined: Sat Aug 06, 2022 1:44 am
Location: Austin, TX

Servo controlled deadbolt

Post by EmilyPearson » Sat Aug 06, 2022 2:57 am

I've started a new project. Having tired of digging for door keys with an armload of groceries and already having my security gate/garage door fob in my hand when I get to the door I decided to use a spare button on the fob to unlock my door.

I wanted a solution that would have the least impact on the existing door hardware. I didn't want to have to figure out how to make wiring not look ugly so I have settled on a completely wireless approach.

The unit mounted to the door replaces the thumbscrew and is attached with the same two screws. On the outer surface is a standard size R/C servo. Inside is a Raspberry Pi PicoW, a TBD lipo battery and charger, and various acrylic and metal servo parts.

The fob interface uses a garage door opener receiver wall wart, and a ESP-01 WiFi capable microcontroller. I haven't decided how to power the ESP-01 just yet but I probably will use the charger that I use to periodically top off the door battery. The receiver pairs nicely with my fob and contains its on power supply.

Prototype BOM, subject to change:
Deadbolt
1 ea. Raspberry Pi PicoW
1 ea. Lipo Battery
1 ea. SparkFun lipo charger PRT-15217
1 ea. goBILDA 1906 Series Lightweight Servo Hub
1 ea. custom laser-cut acrylic enclosure
1 ea custom laser-cut acrylic servo to deadbolt actuator

Receiver
1 ea. ESP-01 WiFi Module
1 ea. Linear MDR/u receiver
1 ea. usb c breakout for power input
1 ea. custom laser-cut acrylic enclosure

If anyone shows any interest, I'll post the code when it's done. In brief, the receiver closes a contact pair for 0.5 second when the fob is triggered. I will sense this contact closure with a GPIO input on the ESP-01. The ESP-01 will send a message to the PicoW in the door unit via UDP protocol. The PicoW will generate a PWM signal to activate the servo depending on the state of the last actuation, sensed by two Hall effect switches and a magnet on the servo actuator arm.
Forum Pico Case.jpeg
Cut pieces for deadbolt enclosure
Forum Pico Case.jpeg (5.49 KiB) Viewed 140073 times
Servo Shaft Adapter.jpeg
Servo to deadbolt actuator adapter
Servo Shaft Adapter.jpeg (6.67 KiB) Viewed 140070 times

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