Published November 12, 2018 © GPL3+

Light Activated Blinds Opener/Closer

The device will cause blinds to open/close based on outside light levels, and graph when the blinds are opened/closed.

BeginnerFull instructions provided3 hours1,734

Things used in this project

Hardware components

Particle Photon

Zipties

FITEC FS5103R Continuous Rotation Servo (with Circular Shaft Attachment)

Resistor 220 ohm

Photo resistor

Male/Male Jumper Wires

Anker Power Pack

Velcro

Solderless Breadboard Half Size

Sheetmetal Brackets (135 deg and 90 deg, see pics in story)

Steel Paper Clip

Software apps and online services

IFTTT Maker service

Google Sheets

Hand tools and fabrication machines

Wire Cutters

Story

Introduction

This project uses two Particle Photons to open/close window blinds automatically, based on outside light conditions. The opening and closing of the blinds are graphed on Google Sheets through IFTTT.

Youtube Video

How It Works

Two Particle Photons are used, one connected to a photo-resistor, and the other connected to a continuous rotation servo. The voltage across the photo-resistor is checked every 5 seconds by the sensor photon, and is compared to the last reading of the photo-resistor, and also to a preset voltage threshold value that distinguishes between light/dark. If the newest voltage is lower than the threshold condition but the previous voltage is higher than the threshold condition, then the environment has gotten darker. If the opposite is true, and the newest voltage is higher than the threshold condition while the previous voltage is lower than the threshold condition, then the environment has gotten lighter. The sensor photon will publish either a “light” event or a “dark” event based on the logic.

The first pair of IFTTT programs wait for the sensor photon to publish an event; one program responds to“light” and publishes a "1" with a timestamp to Google Sheets, while the other program responds to “dark" and publishes a "0" with a timestamp to Google Sheets. Each publish from IFTTT automatically adds another row to the Google Sheet, and a graph of the events with respect to timestamps is automatically updated. Here is a link to our Google Sheet: https://docs.google.com/spreadsheets/d/1XVPyQSOPuph97yQJBeigwkboHUfV9TTU8nzb2Faqog0/edit?usp=sharing

IFTTT Programs that Listen to the Sensor Photon Events

Google Sheets Data (automatically received from IFTTT)

Google Sheets Chart From IFTTT Data (automatically updates)

A second pair of IFTTT programs listen to the first pair of programs, and publishes a notification to a smartphone that the blinds have been either opened or closed.

IFTTT Programs that Send Notifications to Smartphone

Screenshot of Smartphone Notifications

The servo photon is also subscribed to the ‘light” and “dark” events. If a “light” event is received, then the servo will rotate for 5 seconds, causing the blinds to open. If a “dark” event is received, then the servo will turn in the opposite for 5 seconds, causing the blinds to close. Once the motor has finished turning, an “on” event is published by the servo photon. The sensor photon is subscribed to this event, and once the “on” event is published, the LED on pin D7 will turn on for 10 seconds, verifying that the motor was turned.

How to Build

Sensor Photon

Insert one Particle Photon into the breadboard.
Insert the photo-resistor into pins A0 and A5, and insert the 220Ω resistor into pins A0 and GND (neither has polarity, so orientations do not matter). (See Schematics at the end of the story.)
Connect one power pack to the Particle Photon via micro-USB.
Place the sensor photon on the window sill, with the photo-resistor pointed outside.

Sensor Photon in Window

Servo Photon

Insert the other Particle Photon into the breadboard.
Connect the servo to the Particle Photon via jumper wires (Red to Vin, Brown to GND, and Orange to D0). (See Schematics at the end of the story.)
Connect the other power pack to the Particle Photon via micro-USB.

Servo Photon Setup

Bracket Connection

Put the bracket on top of the shade support and use four Zip-Ties (in an X) to hold in place, as shown.

Zip-Tie Connection

Attach the 90 degree bracket to the 135 degree bracket with the 4mm hex bolt and wingnut through the predrilled holes, and attach Velcro to the outside of the bracket as shown.

Bracket-Bracket Connection

Blinds/Servo Connection

Use part of a steel paper clip to attach the circular attachment that came with the servo motor to the blinds, as shown.

Top of Circular Attachment

Bottom of Circular Attachment

Attach Velcro to the side of the servo, as shown. (Notice the servo shaft is above and to the left of the Velcro.)

Servo Velcro (Notice the Shaft is Top Left)

Put the circular attachment onto the servo, and connect the servo to the bracket with the Velcro, as shown.

Servo to Bracket Connection

Blinds/Photon/Power Pack Connection

Attach the servo Photon and its power pack to the outside of the top of the blinds with Velcro, as shown.

Servo Photon and Power Pack Mounted onto Blinds

Setup On Blinds

Final Setup on Blinds

What Can Be Done Differently

Plug each Photon into a wall outlet using a 5V phone charger with a Micro-USB cable, instead of using a portable power pack.
In order to reduce uncertainty of servo position, the paper clip that connects the circular servo attachment to the blinds could be glued in place.
Instead of using the non-destructive modifications to the blinds that are shown in this project, one could drill mounting holes and use self-tapping screws to mount different brackets to attach the servo, Photon, and power pack.

Code

int power = A5; // This pin puts a voltage across the photoresistor so as the light intensity changes, the voltage across the photoresistor changes.

int photoresistor = A0; // Setting which pin reads the photoresistor

int threshold_condition = 100; // this is the threshold of the photoresistor reading that distinguishes bewtween dark and light. We accomplished this by using Tinker to analog read the A0 pin at different light levels.

int tempvalue = 0; // Setting an arbitrary initial value to compare to later in the code
 
int analogvalue=0; // Setting an arbitrary intial value to compare to later in the code

void setup() {

    
    pinMode(photoresistor,INPUT); // Setting the photoresistor pin (A0) as an          input
    
    pinMode(power,OUTPUT);// Setting the power pin (A5) as an output

    
    digitalWrite(power,HIGH);// Turning on the power (3.3V) of the A5 pin

   
    Particle.variable("analogvalue", &analogvalue, INT); // Sends every
    // photoresistor reading to the cloud to be stored. 
    
   Particle.subscribe("talkback", myHandler);// Subscribing to the "talkback" event sent by the Servo Photo, so that this Photon's D7 LED will light up everytime the servo runs. This allows for two-way communication between Photons.
   
}




void loop() {
    tempvalue = analogvalue; // Setting the inital condition for the toggling below
   
    analogvalue = analogRead(photoresistor); // Reading the output of the photoresistor pin

   if (analogRead(A0) >= threshold_condition & tempvalue < threshold_condition){
       Particle.publish("photoresistor", "light", 60, PUBLIC);
    // if the current photoresistor reading indicates that it is light, and the previous photoresistor reading indicated it was dark, then publish an event called "photoresistor" with the data "light" to tell the servo to open the blinds
    // The comparison between the current and previous photoresistor reading prevents this loop from publishing "light" at every iteration. Therefore, "light" will only be published when the ambient light intensity moves from dark to light.
    // We found it easiest to publish in this manner, it was more difficult to prevent the servo from running if this loop published "light" at every iteration.
   }
   
   if (analogRead(A0) < threshol_condition & tempvalue >= threshold_condition){
   Particle.publish("photoresistor", "dark", 60, PUBLIC);
    // if the current photoresistor reading indicates that it is dark, and the previous photoresistor reading indicated it was light, then publish an event called "photoresistor" with the data "dark" to tell the servo to close the blinds
    // The comparison between the current and previous photoresistor reading prevents this loop from publishing "dark" at every iteration. Therefore, "dark" will only be published when the ambient light intensity moves from light to dark.
    // We found it easiest to publish in this manner, it was more difficult to prevent the servo from running if this loop published "dark" at every iteration.
   
   
   }
  
    delay(5000); // Puts a 5 second delay between each loop to allow time for the servo to run completely


}




void myHandler(const char *event, const char *data){
 if (strcmp(data,"ON")==0) {
     digitalWrite(D7,HIGH);
     delay(5000);
     digitalWrite(D7,LOW);
     // This loop is subscribed to the servo photon's "talkback" string, which tells the D7 LED on this Photon to light up each time the servo is run. This allows for two-way communication between Photons.
     
 }
}

Servo myservo;

int pos = 0;
void setup() {
  
//This causes the servo photon to be subscribed to an event (photoresister) that the sensor photon published.
Particle.subscribe("photoresistor", myHandler);


}

//The code below actuates the servo in either the clockwise direction or the counter-clockwise direction to open/close the blinds.
void myHandler(const char *event, const char *data)
{

//If a "dark" data is recieved in the "photoresister" event, then this section of code will run.
 if (strcmp(data,"dark")==0) {
   
     //The pin that the motor is attached to is activated (in this case D0).
     myservo.attach(D0);
     
  //The write command sends a signal to the the pin that the motor is attached to(values beteen 90 and 180 result in clockwise rotation, with values closer to  180 being faster).
myservo.write(110);

// Here, the delay of 5000 milliseconds causses the motor to turn for 5 seconds.
delay(5000);

 //Then, the detach command causes power to stop being sent to the pin that the motor was previously attached to, casuing the motor to stop.
myservo.detach();

// Once this happens, an "ON" event is published to the cloud, and will be picked up by the sensor photon. This is to turn on the D7 LED of the sensor photon. This allows for two-way communication between Photons.
Particle.publish("talkback", "ON", 60, PUBLIC);
}



//If "light" data is recieved in the "photoresister" event, then this section of code will run.
else if (strcmp(data,"light")==0) {
  
  //The pin that the motor is attached to is activated (in this case D0).
myservo.attach(D0);

 //The write command sends a signal to the the pin that the motor is attached to(values beteen 0 and 90 result in counterclockwise rotation, with values closer to 0 being faster).
myservo.write(70);

// Here, the delay of 5000 milliseconds casuses the moter to turn for 5 seconds.
delay(5000);

 //Then, the detach command causes power to stop being sent to the pin that the motor was previously attached to, casuing the motor to stop.
myservo.detach();

// Once this happens, an "ON" event is published to the cloud, and will be picked  up by the sensor photon.  This is to turn on the D7 LED of the sensor photon. This allows for two-way communication between Photons.
Particle.publish("talkback", "ON", 60, PUBLIC);
}

//The only events being published by the sensor photon are "light" or "dark" so there aro no other possible cases.
else{}
}

Credits

Eric Adkins

1 project • 0 followers

Will Slack

1 project • 0 followers

Light Activated Blinds Opener/Closer