Smart Door Knob

Have you ever come back to your house only to realise that you had left your room lights turned on the entire time? Fear not, as we propose a smart hack that ensures that you always leave with all the lights turned off. Presenting, the SMART DOOR KNOB.

The Smart Door Knob is a personal ambient display device which can be setup in your home. It is just a simple door knob, but embedded with a strip of LED lights. The idea behind creating a smart door knob is to remind people before leaving the house that the lights in different rooms are still turned on. Thus, people are reminded about the status of their rooms without having to think twice or walk all the way back to check on it.

See video of it in action here: https://vimeo.com/362854918

PROBLEM WE TACKLE:

People tend to forget to switch off their room lights and leave their house, which is a waste of electricity and runs up the bill.

SOLUTION WE PROPOSE:

An ambient display device embedded in the human life without interfering in their daily activities to remind us about the status of various rooms - The smart door knob: door knob interfaced with LED strip which glows in different colors associated with different rooms.

EQUIPMENT USED:

S.No	Item Name	Quantity
1.	Particle Argon Boards	3
2.	Analog Light Sensor- TEMT6000	2
3.	NeoPixel LED Strip	1
4.	Breadboard	3
5.	Powerbank	2
6.	Connecting Wires	20
7.	Solder Iron and Flux	1
8.	Wooden Case	3

CONNECTIONS:

The analog sensor has three pins: VCC, Ground and Signal. We connect the signal pin to A0 of the particle Argon board and VCC and ground to its respective positions.

Light Sensor and Particle Argon setup

Similarly, the LED Strip has three pins: VCC Ground and Data. We connect them to VCC, Ground and Digital Pin D2 of the Particle Argon.

LED Neopixel Strip and Particle Argon setup

SETUP:

First, we solder the wires onto our analog sensor, TEMT6000 to ensure there is constant contact and no loose ends. Soldering the wires enables a solid output and no errors due to breakage of continuity. Similarly, we solder the LED strip with connecting wires for the same purpose. In our proposed model, we set up the door knob at the exit of the house, and took two rooms under consideration, the bedroom and the bathroom. In each room, we setup particle Argon boards interfaced with the TEMT6000, an analog light sensor. Another particle Argon connected with the NeoPixel LED strip was setup at the door constituting the Smart door knob setup. We enclose all the three devices into wooden boxes, laser cut in the makerspace at CMU. This is done just to put forth a compact neat setup whose presence is not visible as an electronic setup.

Particle Argon setup in the different rooms

WORKING:

The three particle Argons are connected to the same console, thus share the same cloud. Thus the three particle boards can now publish and subscribe data from the common cloud.

The light sensor boards, setup in the rooms, constantly read the brightness levels in the rooms. They publish a message onto the cloud whenever the lights in the room are turned on.

Bedroom sends a “toggle-led-bed” message to the cloud.
Bathroom sends a “toggle-led-bath” message to the cloud.

These messages are published onto the common cloud. The particle connected to the smart door knob subscribes these messages. Whenever it sees a message from the bedroom, it turns on the strip of LEDs and the color indication is red. For the bathroom, the LED strip turns blue. If both the lights are turned on, we see an alternating strip of blue and red lights.

Flow chart indicating flow of events

HUMAN INTERACTIONS:

There exist minimal human interactions with the device. If the lights in the rooms are switched on, then the door knob glows. A human exiting the house can clearly see a glowing door knob which indicated that he has left the lights in his room turned on. If all the lights in the house are turned off, the LED Strip will not glow. Thus, an ambient non-obstructive display device was created to solve the problem and this device was suitably embedded in human daily life activities.

Code:

Door Knob Code:

// This #include statement was automatically added by the Particle IDE.
#include <neopixel.h>

#define PIXEL_PIN D2
#define PIXEL_COUNT 28
#define PIXEL_TYPE WS2812
 
Adafruit_NeoPixel strip = Adafruit_NeoPixel(PIXEL_COUNT, PIXEL_PIN, PIXEL_TYPE);
 
 
void setup() {
    strip.begin();
    strip.show();
 
    Particle.subscribe("toggle-led-bat", toggleBat, MY_DEVICES);
    Particle.subscribe("toggle-led-bed", toggleBed, MY_DEVICES);
}
 
void loop() {
    uint32_t c = strip.Color(0, 0, 0);
    for( int i = 0; i < strip.numPixels(); i++ ) {
        strip.setPixelColor(i, c); // set a color
       
    }
    strip.show();
    delay(10);
}
 
void toggleBat(const char *event, const char *data) {
    uint32_t c = strip.Color(255, 0, 0);
    for(int i = 1; i < strip.numPixels()-1; i = i+2) {
        strip.setPixelColor(i, c); // set a color
    }
    strip.show();
    delay(1000);
    Serial.println("rece");
}
 
void toggleBed(const char *event, const char *data) {
    uint32_t c = strip.Color(0, 0, 255);
    for(int i = 0; i < strip.numPixels(); i = i+2) {
        strip.setPixelColor(i, c); // set a color
    }
    strip.show();
    delay(1000);
    Serial.println("rece2");
}

Click to Expand

Bedroom/Bathroom Device Code:

int ledPin = D7;
 
void setup() {
    pinMode(ledPin, OUTPUT);
}
 
void loop() {
    int analogvalue = analogRead(A0);
    if(analogvalue > 0) {
        Particle.publish("toggle-led-bat", PRIVATE);
        digitalWrite(ledPin, HIGH);   // Turn ON the LED pins
        
    } else {
        digitalWrite(ledPin, LOW);   // Turn OFF the LED pins
    }
    delay(1000);               // Wait for 1000mS = 1 second
}

Click to Expand

CHALLENGES FACED:

Interfacing multiple Argon devices onto the same platform. Having multiple boards on the same platform required constant check on which code was uploaded onto which board.
Wifi (CMU-DEVICE) posed to be an issue.
Time latency. The lag between sending a command from the door and receiving it onto the door knob had to be calibrated.
Spelling mistakes: The particles subscribe and publish data with respect to a toggle. Any spelling errors in this leads to failure of the action.
Scaling to multiple rooms: We need to devise a mechanism without the use of mapping (light1 corresponds to room1 and so on) when we scale the same project to multiple rooms.

RESULTS:

Thus, an ambient non-obstructive display device was created to serve the purpose of a smart reminder to switch off lights in various rooms while exiting the house. This personal device could be installed in your homes. The smart door knob is an extension of the regular door knob but now feeds on data from the rooms and gives us a display output which is meaningful and useful. A system to track and remind humans about the status of various rooms was successfully built and installed. The problem statement chosen was successfully solved.

Bedroom Device