The key to my apartment never worked quite right because it is a copy of a copy of a copy. I am fairly certain that the dead bolt is original to the building and the property manager seems to have lost the original key years ago. As a result unlocking the door was always a pain. Changing the lock wasn’t an option, but eliminating the need to use a key was.

Parts:
Arduino Uno R3

RF transmitter and receiver

Servo

2 Push Button Switches

Red LED

Green LED

Various Resistors

piezoelectric speaker

Perf Board

Mounting Parts

I used a couple of pieces of acrylic that I acquired in the dumpster of the plastic shop next to my place of work (they throw out alot of small pieces like this). Alternatively another material could be used if you don’t have access to acrylic, but it is easy to work with and looks cool.

Using a piece of paper trace the mounting holes for your dead bolt and transfer them onto your acrylic sheet. Since most dead bolts are going to be slightly different I am not sharing the template I made out of a piece of paper (mainly because it isn’t anything worth sharing).

Leave the paper covering on while working with the acrylic. The paper makes it easy to mark where to cut/drill as well as protects the material from scratches. Once all of your cuts are made and your holes are drilled you can start installing components such as LEDs and switches.

I used an old parallax servo I had in my parts bin. This small servo is more than strong enough to turn the deadbolt. In order to attach the servo to the lock shaft I used epoxy putty. Epoxy putty is very easy to use and is extremely versatile. The wire you see sticking out of the putty will be used as the arm for the limit switch.

At some point the wires to my servo had been cut so I had to open the case and solder on new ones. I took that opportunity to solder on a second wire to the 5v line and connected it to the limit switch arm.

Screws were countersunk from the back of the acrylic. A wire was attached to each screw and then to a digital pin on the Arduino. When the wiper with the 5v wire touches the screw it pulls the digital pin high on the Arduino. Please see the schematic for further details.

Disclaimer: I am not a programmer and therefore the below code may not be the most efficient. Feel free to improve the code for your own uses if you see any errors or problems. It works for me so I hope it works for you.

// turn CW to lock and CCW to unlock //1700 CCW; 1500 Stop; 1300 CW //written by Chris Rybitski #include

Servo deadbolt; // create servo const int CWLimit = 6; // Limit Switch on 6 Unlock const int CCWLimit = 7; // Limit Switch on 7 Lock const int Redbtn = 12; //red push button const int Blackbtn = 8; //black push button const int GreenLED = 10; // Green LED const int RedLED = 11; //Red LED const int Ch1 = 5; //rf channel 1 const int Ch2 = 4; //rf channel 2 const int Buzz = 9; //buzzer int Unlock = 0; int Lock = 0; int timer = 0; boolean UnLcomplete = false; boolean Lcomplete = false;

void setup() {

Serial.begin(9600);

deadbolt.attach(3); // attaches the servo pinMode(GreenLED, OUTPUT); pinMode(RedLED, OUTPUT); pinMode(Buzz,OUTPUT); pinMode(CWLimit, INPUT); pinMode(CCWLimit, INPUT); pinMode(Redbtn, INPUT); pinMode(Blackbtn, INPUT); pinMode(Ch1, INPUT); pinMode(Ch2, INPUT);

//set LED’s and Buzzer to be off by default digitalWrite(GreenLED, HIGH); digitalWrite(RedLED, HIGH); digitalWrite(Buzz, HIGH); }

void loop() { if (digitalRead(Ch1) == HIGH || digitalRead(Redbtn) == LOW){ //If remote or button is pressed if(UnLcomplete == false){ //dont run unlock if door is already unlocked Serial.println(“UnLock”); Unlock = 1;}} if (digitalRead(Ch2) == HIGH || digitalRead(Blackbtn) == LOW){ //If remote or button is pressed if(Lcomplete == false){ //dont run lock if door is already locked Serial.println(“Lock”); Lock = 1;}}

//—————UNLOCK————————- if (Unlock == 1){ timer = 0; while (digitalRead(CWLimit) == LOW){ if (timer > 1500){ digitalWrite(Buzz, LOW); delay(500); digitalWrite(Buzz, HIGH); } else{ deadbolt.write(1700); timer++; delay(1); }} deadbolt.write(1500); //servo stop digitalWrite(RedLED, LOW); digitalWrite(GreenLED, HIGH); UnLcomplete = true; //unlock complete Lcomplete = false; //reset Lock boolean digitalWrite(Buzz, LOW); delay(100); digitalWrite(Buzz, HIGH); Unlock = 0; //reset

}

//————–LOCK—————————- if (Lock == 1){ timer = 0; while (digitalRead(CCWLimit) == LOW){ if (timer > 1500){ digitalWrite(Buzz, LOW); delay(500); digitalWrite(Buzz, HIGH); } else{ deadbolt.write(1300); timer++; delay(1); }} deadbolt.write(1500); digitalWrite(GreenLED, LOW); digitalWrite(RedLED, HIGH); Lcomplete = true; //lock complete UnLcomplete = false; //reset Lock boolean digitalWrite(Buzz, LOW); delay(100); digitalWrite(Buzz, HIGH); delay(50); digitalWrite(Buzz, LOW); delay(100); digitalWrite(Buzz, HIGH); Lock = 0; //reset } }

Currently the unit is powered via the USB port using a cell phone charger. There are plans to wire a separate 5 volt supply that does not require the usb cable extending past the door. Although a key can still be used to unlock the door from the outside I am also planning on adding a battery back up in case of power failure .