This project uses an Arduino microcontroller and an RDM630 RFID receiver to control access to my garage. This is very handy when I need to get in with a handful of groceries. I carry an RFID card in my wallet that works just like the key chain FOB. Several spare FOBs have been given to family members who need access to the garage from time to time. I built a similar unit that cycles the deadbolt on a door leading from the garage into my house. When an authorized person wants to enter the garage they just wave their FOB or card across the antenna coil once which cycles a relay on and off one time. The relay is connected to the garage door manual operation button and behaves just like pushing the button one time. If the door is closed it opens, if the door is open it closes and if the door is in motion it stops. I added the 'SCAN HERE' label after I made the movie. It just looked too plain.
Step 1: Cards and FOBs
There at least two form factors that can work with this project. Both work equally well. The card is great for guys since it can be carried in a wallet, then the entire wallet is waved across the antenna coil. No need to remove the card. There have been no problems with the RFID antenna coil sensor damaging the mag-stripes on other cards I carry.
The coil inside the key ring FOB is wound so perfectly. The TV show "How It's Made" has a piece about making headphones coils that shows how their coils are made. There is also another piece about making speakers that shows coil winding as well. How It's Made is my favorite TV show. Ever.
Step 2: First Prototype:
The original design was constructed on an experimenters breadboard socket. I decided to leave it in the socket and put it into service. It worked pretty well with a connector being accidently unplugged every now and then. After about a year or so I decided it was time to construct a more permanent version.
A spare antenna coil was mounted to a piece of perfboard with a 7 pin male header. Just 2 of the pins are used, the others add stability when plugged into experimenter board. This comes in handy when experimenting with RFID.
The RFID cards are 25KHz and are of the RDM 630 variety. I found some receivers from different suppliers would work and other would not. All of the RDM 630 UART receivers I purchased from Seeed Studio worked, but they no longer sell the exact type I am using here. I have found some on EBAY that worked fine. Make sure you purchase the UART type and NOT the Weigand. The Weigand type will not work with this project since it uses a different protocol.
Step 3: PC Board Construction:
The pc board version was constructed using Veroboard. It is a pc board with a similar copper foil pattern to that of an experimenter's socket. This makes for quick reconstruction of the device. In less than a day it was up and running.
lightly sanding the copper traces to a shine will make for much better solder connections. If you take the time to breadboard the project first, you can just copy the breadboard to the pc board.
Step 4: Schematic
Just wire up components as outlined in the schematic. Wiring is not critical. Use your imagination when building this. If you are new to Arduino you may want to consider purchasing a starter kit that has many components to get you started right away. They are sold by Radio Shack and many other vendors online. There should be a instructions with the kit to help you build a number of projects. The sky is the limit with these cool microcontrollers! I am hooked!
Step 5: Construction Hints
I am a big fan of the RBBB PC boards from Modern Device. They are cheap and make using the Arduino much more efficient. Kits can be ordered with all of the parts or just the PC boards. I made an Excel spreadsheet to use as a template for keeping track of pin assignments. I have a larger one that is more practical to use and fits on a 8.5 x 11 paper. You can download it here:
Step 6: Arduino Sketch
On July 8, 2014 I uploaded a .txt version of the Arduino sketch. There was problem just cutting and pasting the sketch into this Instructable window as it would cut off some of the sketch.
- Just download the above file and open it in Word or any simple word processor.
- Start a new version of the Arduino programming software.
- Copy and paste the text into the Arduino software.
- You man need to adjust the deadbolt motor run time. They are in milliseconds (1 second = 1000 milliseconds).
These lines are located at the beginning of the sketch, lines 14 and 15 from the top. One is for open and the other for close. They will likely need to be the same, but I added a second variable just in case. Set the times to run just very slightly longer than the deadbolt takes to fully cycle. There is a built-in clutch in the deadbolt housing to prevent damage from overruns. When I built this circuit, the motors ran opposite of what was intended. Just unplug and reverse the motor connector where it plugs into the circuit board. The Arduino has no way of knowing which direction the motor is actually running in.
int A_Delay = 800; //----- RELAY A ON TIME -----
int B_Delay = 800; //----- RELAY B ON TIME -----
If you have any problems, suggestions or questions drop me a line. This project is much simpler than the RFID Deadbolt Opener and would be a good one to start with. If you can build this, you can build the Back Door Deadbolt version. That version just has more outputs and a longer sketch.
If this all looks intimidating, try starting out with the numerous tutorials on Instructables and www.arduino.cc. If you like to tinker with electronics, Arduino will open up a new world of fun and exciting possibilities. By all means - PLAY!
Step 7: Some Final Ideas
I have another instructable posted that is based on this project. It uses two relays and operates the deadbolt on an exterior door to my house.
A trip to your local beauty shop supplier can yield a gold mine of construction materials. The foam sanding blocks for fingernails are great to buff the patina from the copper foil traces and make them shine.
Pick up a gallon on acetone while you are there. An important couple of safety tips should be adhered to at all times when using acetone. READ THE LABEL AND OBEY IT. It is flammable! Store it in a cool place where it's plastic container will not be damaged or overheated. Acetone has nasty vapors, so use it in a well ventilated area - like outside. Acetone will melt most plastics. Some plastics are acetone proof, like the bottle it comes in. I find it useful to get the gum left behind after peeling labels off my windshield. Solder flux can be dissolved with acetone. I like to pour some acetone in a shallow glass dish and paint it on the solder joints until they are clean. Make sure to only use the dish for this purpose, don't put it back in the cupboard! Acetone will dissolve relay cases and other plastic electronic components, so use your own judgment. It can be dangerous if used carelessly, but if used per the label instructions it is amazing stuff.