Refrigerator Diagnostics Group #14 Jacob Belica Bradley Snyder Darwin Walters

Overview  Introduction  Features and Benefits  System Overview  Module Descriptions  Prototyping  Completed PCBs  Project Outcome  Future Work

Introduction  Revolutionize your fridge to the next level without having to spend thousands of dollars  Allows for better understanding fridge including detecting expired items, tracking how much remains of certain items, and taking snapshots which can be viewed using an Android phone

Features and Benefits Features  Access your fridge’s cameras to take a look inside using your Android phone  Information to be sent about quantity of product sitting on weight sensors  Methane sensors to detect when fruits/vegetables have expired Benefits Grocery shopping is made easy with the ability to check contents of your fridge Heads up reminder for you to pick up more product when you are out and about No more surprises of spoiled food when you open up your fridge

System Overview Block Diagram of System

BeagleBone Black Operation

Design - BeagleBone Black  Sufficient amount of multipurpose GPIO pins  Runs full Linux distribution which provides increased functionality and ability to run without requiring a computer

BeagleBone Black - Verification  Wrote simple program to test for interfacing GPIO pins with programs  Using python, tested and verified being able to transfer textual data as well as images to Android phone

Android Application Operation

Design – Android Application  Connect to BeagleBone Black wirelessly over subnet – either a wireless network or a VPN  Process incoming data streams (text and images)  Display the data received from the BeagleBone Black on main screen

Android Application - Verification  Connect to devices on same wireless network using simple socket program  Read in single string sent from connected device and display it in console  Wrote program to recreate image sent wirelessly

Design – Methane Module  MQ-4 Methane Sensor, resistive sensor  5V max output  Requires 5V input – runs at 5.1V  Requirement : Illustrate change from normal voltage from increases of methane  Testing : Observe changes from normal voltage level with ripe and fresh vegetables over 5 minute span + -

Methane Module - Verification  Simulated produce bins with sealable containers  Voltage value read from Arduino Analog Input pin  Example Test : Normal integer in container at 75 degrees = 150 (.733 V)  Fresh Kale: 150 – 165 (.733 V V)  Ripe Kale: 150 – 223 (.733 V – V)  Distinct difference between fresh and ripe produce Methane Module connected to Arduino

Design – Flash Module  Illuminates inside of fridge  Super bright LEDs  Bipolar junction transistor as switch

Design - Camera  Camera connects to BeagleBone Black using 20 individual pins  Using I2C interface, camera and BeagleBone Black communicate  BeagleBone Black processes incoming data stream and recreates original image

Camera - Verification  Using shell command, checked to make sure camera was present on I2C bus  Wrote a program to save a new image taken by the camera in working directory OV7670 Camera

Load Cell – Requirements  Load cell must accurately measure weight from items being placed on it by amplifying sense voltage through in- amp and relaying signal to ADC to be read by BeagleBone  Weight sensor will notify user when item is near depletion

Load Cell - Verification  Load cell sense voltages after in-amp need to have range of: 1) 0.65 V V (no weight -> max weight) 2) 0.82 V V (no weight -> max weight) Offset is used for lower voltage of first load cell to account for difference.  V ref set to 0 V to prevent clipping from in-amp

Load sensor Transferring from FSR to Load sensor to Scale Force Sensor resistorKitchen scale (load sensor)

FSR Measurements  Using two Force Sensitive Resistors for measurements Force (lbs) Force (N)FSR Resistance (Ω) (FSR + R) (Ω) Current through FSR + R Voltage Across R None ∞∞0 mA0V kΩ37 kΩ0.161 mA1.3V kΩ15.96 kΩ0.301 mA3.1 V kΩ11.12 kΩ0.434 mA4.5 V Ω kΩ0.501 mA4.9 V

Load Sensor Measurements

Weight Module Schematic Kitchen scale (as strain gauge) with AD622 In-Amp

Design - ADC MCP3008 Pinout

MCP Operation  Activated by setting CS low  Input is start bit followed by 4 channel selection bits  Output is one null bit and followed by 10 data bits  Not in use when CS is set high MCP3008 Timing Diagram

MCP Testing

Design – Logic Level Converter  Shifts 3.3 V to 5 V from BeagleBone to MCP3008  Shifts 5 V to 3.3 V from MCP3008 to BeagleBone 3.3 V to 5 V Shift Component5 V to 3.3 V Shift Component

Test – Logic Level Converter  Requirements: - Input to MCP3008 is in between 5 V and 5.6 V - Input to BeagleBone is in between 2.5 V and 3.3 V  Test : Input 3.3 Vpp and 5 Vpp with offsets into respective inputs, observe outputs

Test Results – Logic Level Converter  Input : Channel 1  Outputs : Channels 2 and V to 5 V Shifter Component 5 V to 3.3 V Shifter Component

Prototypes – Breadboard Circuits Flash Module Methane Module  Testing done with Arduino Uno  Serial monitor readings, test circuits  Durable compared to BeagleBone Black

Prototype load sensor Prototypes – Breadboard Circuits (cont.)

Prototypes – Vectorboard Logic Level Converter

Completed PCBs Main Fridge Board

Completed PCBs Methane ModuleFlash Module

Final Product Load Cell Logic Level Converter In Amp and ADC BeagleBone Off Screen : Methane Module

Project Outcome  Successes –Distinct differences between fresh and expired produce readings –Program interfacing and overall functionality  Challenges –Integration from Arduino prototypes to BeagleBone Black –Getting camera to interface and function properly –Reverse engineering load sensor –PCB functionality

Future work  Fully functional PCB  Implementing design into fridge  Image processing for better view of fridge’s contents  Switching for power conservation

Questions