Smart locks are a highly convenient way to secure a house, and they can have their number of connectivity options expanded even further by connecting them to an IoT home assistant service such as Google Assistant or Amazon Alexa.
Jithin Sanal’s project uses Amazon’s Alexa skill to automatically secure a custom door locking mechanism without the need for Bluetooth or a fingerprint. It is based around a Nano RP2040 Connect, and due to its onboard connectivity suite, can talk with the Arduino Cloud. Other than the Nano, Sanal designed a simple PCB with pads for a buzzer, voltage regulator, and several LEDs for monitoring its current status. The circuit also includes a relay that applies power to a solenoid which acts as a deadbolt when power is applied.
After receiving the bare PCB and soldering each component onto it, Sanal moved onto writing the code for his creation. In simple terms, the Arduino Cloud project contains a single variable for getting/setting the value of the lock. Then whenever this changes, a method is called in the firmware that sets the solenoid to this new state and makes a few beeps with the buzzer. The last step was associating the Arduino Alexa skill with the IoT device, thus letting someone set the lock as a dedicated device.
You can see more details on this project in Sanal’s Hackster.io write-up.