Student Projects
By Eric Levy, Thomas Law, and Ryan Sparks
Overview of what project is:
The myFridge is a new way to keep your drinks safe and cool. It uses the National Instruments myRIO as an embedded computer to read and control and number of sensors and actuators. The myFridge has an automatic lock that keeps would-be drink thieves from getting in. The lock is a solenoid that extends a piston into a metal bracket on the door of the fridge. When the piston is extended the fridge door cannot be opened. To disengage to lock the user can enter a code on the keypad; if the code is valid the solenoid pulls back and unlocks the fridge. A friendly "Access Granted" message is then played out of the speakers attached to the fridge. The door also has a touch sensor that can detect if the door is opened or closed. After being opened the fridge will check if the door has been closed once again and reengage the lock once it has been closed.
Aside from locking the door, the myFridge can also keep track of your stock of drinks. When taking a drink out of the fridge the user can scan one of the many RFID tags that hang inside the fridge. Each tag represents one of the brands of drinks contained in the fridge. When a tag is scanned by the RFID Scanner atop the fridge, the myRIO decrements the inventory count for that drink. The current stock for the fridge can be retrieved by texting the word Stock to 910-44myRIO (910-446-9746). This is accomplished by using a Google Voice account that can alert the myRIO when a text has been received, and also send data back from the myRIO to a phone. The myFridge also has a host side user interface that allows the user to update the stock manually for when he or she restocks the fridge. The fridge also has its own custom temperature control. Rather than use the generic dial most mini-fridges come with, the myFridge has an exact temperature set point that is kept by a thermistor and relay feedback loop that powers the compressor on and off. With the myFridge you can always know when it’s time to buy more drinks, and make sure they are safe and cold.
Picture of project:
Video of project:
Parts List: myFridge BOM.xlsx attached with links
| Item | Quantity | Purchased From |
| SEN-00250 - Thermistor 10K | 1 | SparkFun |
| PCB Mount SSR, 140 VAC, 3A, 3-32 VDC | 1 | Newark |
| COM-11142 - Door Switch - Momentary | 1 | SparkFun |
| Mounting Brackets (Modified COTS Part) | 1 | Home Depot |
| Solenoid | 1 | Online |
| Door Bracket (Modfied COTS Part) | 1 | Home Depot |
| Rubber Stop for Switch | 1 | Home Depot |
| SEN-11828 - RFID Reader ID-20LA (125 kHz) | 1 | SparkFun |
| SEN-08423 - RFID Reader Breakout | 1 | SparkFun |
| COM-08653 - Keypad - 12 Button | 1 | SparkFun |
| Thru-Hole Op Amp (LM358) | 1 | Sparkfun |
| Linrose B4381H1 10mm Jumbo Flashing Red LED | 1 | Frys |
| Linrose B4383H5 10mm Green LED | 1 | Frys |
| Project Enclosure | 1 | Radio Shack |
| PCB Mount SSR, 60V, 2500 mA, 1.5-5 VDC | 1 | Mouser Electronics |
| Printed Circuit Board | 4 | Radio Shack |
| COM-08310 - RFID Tag (125kHz) | 20 | SparkFun |
| 18 Guage Wire | 25 Ft | Frys |
| 22 Guage Wire | 100 Ft | Frys |
| Speakers | 2 | Frys |
| 12 VAC 700mA Power Supply | 1 | Online |
| Resistors (10K, 20K) | 20 | Radio Shack |
| Mini-Fridge (Chefmate BC-87/H) | 1 | Online |
Wiring Diagram:
Instructions: myFridge Documentation.docx
C or LV?: LabVIEW
Version of LV: 2013
Code: myFridge Source Code.zip attached
Pretty cool. If you are open to suggestions, which I assume you are if I am allowed to post this comment... use latching relays for the solinoid, speaker amplifier power, and maybe even the compressor. They will save some energy. My better suggestion is to implement a weight scale so sense if a can was removed. This could then sound an alarm if the perp did not do the extra physical work of scanning which type of can was removed. Nothing adds insentive better than an annoying alarm.
Great implementation with the sms, but does it tweet? 
