EEL 4924 Electrical Engineering Design (Senior Design) Preliminary Design Report

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1 EEL 4924 Electrical Engineering Design (Senior Design) Preliminary Design Report February 2, 2012 Project Title: Smart Fridge Team Members: Seth Goldberg & Kelly McEachern Project Abstract: Our project is a smart refrigerator module capable of keeping track of its barcode bearing contents. The user will be able to switch between two modes: one to scan in items when placing them into the refrigerator, and the other to scan them out after finishing them, thus creating an up to date inventory. The inventory of the fridge will be sent out as a text message on a scheduled basis, keeping the user informed of the contents of their fridge. The barcode scanner output will be processed by a microcontroller and this will be used to look for the corresponding entry in the barcode database located in onboard ROM.

2 Table of Contents: Project Abstract 1 List of Tables and Figures 3 Introduction 4 Project Objectives 5 Technical Objectives 7 Project Features 7 Concept Selection 7 Technology Selection 7 Division of Labor 8 Gantt Chart 8 2

3 List of Tables and Figures: Figure 1: Block Diagram 4 Figure 2: Example Inventory Text Message 5 Figure 3: Preliminary Design Packaging 6 Table 1: Division of Labor 8 Figure 4: Gantt Chart 8 3

Introduction: Preliminary Design Report: Smart Fridge The Smart Fridge is an innovative technology capable of assisting shoppers everywhere in keeping tabs on their refrigerators contents.

This can result in missing a key ingredient for a recipe, or in a surplus of the same item which may go unused and be wasted.

4 Introduction: Preliminary Design Report: Smart Fridge The Smart Fridge is an innovative technology capable of assisting shoppers everywhere in keeping tabs on their refrigerators contents. Many people often forget the items they need once they arrive at the grocery store, and have no way of knowing what they do or do not currently have. This can result in missing a key ingredient for a recipe, or in a surplus of the same item which may go unused and be wasted. The Smart Fridge system aims to eliminate this problem by allowing users to scan in items when they bring them home from the store and place them in the fridge, while also providing the ability to scan items out of the fridge when they are eaten or disposed of. The easy-to-use interface allows for nearly zero possible human error, perfect for the even the least technologically inclined people. The user need only select the scanning mode, and the system is ready to scan their items into or out of its inventory. Serial μc LED Indicators Battery Force Resistor GSM Module Flash User Interface Buttons Figure 1. Block Diagram 4

Project Objectives: Our project will be able to scan in any barcode and communicate this barcode through a serial connection from the scanner to the microprocessor.

5 Project Objectives: Our project will be able to scan in any barcode and communicate this barcode through a serial connection from the scanner to the microprocessor. The microprocessor will then compare this UPC to a lookup table stored in external memory to obtain the product description. A pointer will be assigned to the address containing the description. When removing an item from the fridge, the UPC will be compared against the current stored items and once a match is found, the pointer pointing to that item s UPC will be reassigned to the location to which the subsequent pointer points, and so on until all pointers have been reassigned. A GSM module will inform user of refrigerator s current stock by sending out the product descriptions indicated by the assigned pointers through an SMS text message to the user s phone. A text message with the entire fridge inventory will be sent after a certain wait period once multiple items have been scanned in during one scan session. After this initial text, single additions or subtractions from the fridge result in a text simply listing the item added or removed. This will cause less clutter of the user s text message inbox and increase readability of the inventory. This allows for portability of the list when the user goes to the store. Figure 2: Example Inventory Text Message 5

We aim to have the system operate on battery power, so low power usage is a must. We are implementing an analog input in the form of a force resistor mounted on the barcode holster.

6 We aim to have the system operate on battery power, so low power usage is a must. We are implementing an analog input in the form of a force resistor mounted on the barcode holster. The resistor s resistance changes with the force applied to it, and the resulting voltage across the resistor will hence vary when placed in a voltage divider configuration. We will read this varying voltage into the Analog to Digital Converter of the microcontroller and compare it to a threshold value to determine whether or not the barcode scanner is currently in use. After the scanner is placed back in it s holster, the system will wait for a predetermined amount of time, then put the system in standby mode and turn off the scanner. This way, in case the user forgets to turn off the system, power is not wasted for a long period of time. Figure 3: Preliminary Design Packaging 6

7 Technical Objectives: Digital Hardware Microcontroller Barcode Scanner GSM Module External ROM Cell Phone Analog Hardware Force Resistor (Input) User Interface Push Buttons (Input) LED Indicator Lights (Output) Project Features: User configurable scan modes, communication schedule and protocol All encompassing UPC database Automatic standby mode after specific idle time Completely standalone and wireless functionality Concept Selection: The problem that sparked this project design is that people often forget to write a grocery list, resulting in the purchase of unnecessary items, or conversely the omission of necessary items. We aim to solve this dilemma by creating a system that provides a list of the user s refrigerator contents, no matter where the user is, provided they own a cell phone. The portability of this solution Technology Selection: Chose a barcode scanner capable of both RS-232 and USB communication for flexibility Using a GSM module in order to send out SMS text messages to user s cell phone Using onboard flash memory to store the large UPC database Chose a force resistor analog input to control the system s standby mode, controlled by the force of the barcode scanner when hung on its holster 7

Division of Labor: Seth Goldberg Kelly McEachern Preliminary Research 40 60 Design Phase 50 50 Board Construction

8 Division of Labor: Seth Goldberg Kelly McEachern Preliminary Research Design Phase Board Construction Test and Debug Physical Assembly Table 1. Division of Labor Gantt Chart: Figure 4. Gantt Chart 8

EEL 4924 Electrical Engineering Design (Senior Design) Final Design Report

EEL 4924 Electrical Engineering Design (Senior Design) Final Design Report April 25, 2012 Project Title: Smart Fridge Team Members: Seth Goldberg & Kelly McEachern Project Abstract: Our project is a smart