virtual wallet

Virtual Wallet

Gates Winkler Yin Shen

Jordan FeiProject Manager: Prajna Shetty

18-52512/02/2009

A handheld device that saves time and money through smart budget management and simplifies shopping experience

Outline

Product Proposal Market Appeal System Description Schematics Simulation Results Layout Evolution Retrospection

Slide 2 Virtual Wallet December 2, 2009

Handheld system that customers pick up upon entering store. Virtual Wallet retrieves information stored on customer’s

SecurOne card. Allows user to set a budget and monitor his/her shopping

Notifies user if they go over budget. Accesses database and applies existing membership discounts Allows online bill payment and self-checkout

Virtual Wallet has functionality to remove items and increase budget if user goes over.

Product Description

Slide 3 Virtual Wallet

Item 1

Item 2

checkout

December 2, 2009

Design Objectives

Minimize cost by optimizing area. Utilize extremely regular layout Robust verification at all design levels

Behavioral Verilog Structural Verilog Schematics


Connection to SecurOne

SecurOne system is an identification card and reader system. Card contains access to user’s personal information, such as

bank accounts. Other 18-525 group designed secure reader system. Reader will be a component of the Virtual Wallet so that the

device can get personal information of the user for checkout.


The SecurOne card will be used in every shopping center. This device can be implemented in any store, as it connects to a

store’s unique database. Saves shopping time and eliminates checkout lines.

Market Appeal


System Description


System Specification


30-bit Integer arithmetic units cumulatively calculates amount spent

Budget and price calculations are done in cents, with the display placing an appropriate decimal.

The RFID obtained by Virtual Wallet is fed to the online database to obtain information about a product and its price

December 2, 2009

Flow Diagram

Scan card and confirm identity

Select bank account and input budget

Begin shopping Price of items bought is added to total

If total goes over budget

Remove items to go back under budget

Increase budget if possible


Apply coupons if possible

December 2, 2009

Functional Design SRAM: Memory to store 32 8-bit item RFID tag. Other

information looked up from Online store database. Second SRAM stores budget.

Adder: Adding block. 30-bit addition Subtractor: Subtracting block. Will handle discounts and

item removals. As items are removed the SRAM remembers the items removed so they will not be added into total costs

Registers: Budget and Total registers store values Comparator: Takes in the budget entered by the user and

total after each item is scanned checks to see if one is over the budget

Touchscreen: User Input (not implemented) Display: (not implemented) Interface to Online Database: Data lines


Functional Design

Item SRAM

Adder Subtractor Comparator Budget FSM

USER ID

Discount FSM

RF

IDke

ypad

Sec

urO

ne c

ard

Dis

play

Sec

urO

ne

Dat

abas

e

SecureOne

Sto

re

Dat

abas

e

Budget register

Input FSM

Checks RFID tag against store database to get price etc.

Make notes in subtractor

Interfacing logic for Database and Display

Battery FSMba

tter

y

total register


Input FSM

Initial

Connect to SecureOne

Select Account

Start Shopping

Don’t input budget

Set budget to max in account

Check account

Input Budget

Not enough in account

Display error

Enough in account

Budget stored in memory

S0

S1

S2 S3

0/0

1/0

1/10/0

1/1

0/0

1/1

0/1


Budget FSM

S0

S1

S2

S3

00/0

10/001/1

11/000/0

01/1 01/1

10/0 10/0

11/0

Initial

Over

Remove item

Go over

Remove item

Remove item

Check SRAM

Make note in subtractor

Total not over budget

Don’t go over

Added another item

Make note in subtractor

Total still over budget

CheckoutCheck SecureOne Database.

Pay


Discount FSM

Initial

Check Database

Check SRAM

Get nothing

Scanned item

discountMake note in subtractor

No discount

S0

S1 S2

0/0

0/0

1/0 0/0

1/1


Battery FSM

S0

S1 S2

0/1

0/0

1/0 1/1

1/0

0/0

Good Battery

Low Battery

Battery Good

Battery Low

Battery Low

Battery Charging

When Plugged in Battery Starts Charging and returns to the correct State when unplugged


Virtual Wallet Top Module


SRAM

Control logic

FSMs

Arithmetic and control logic

Binary to BCD converter and controlling logic

BCD to Binary converter and controlling logic

December 2, 2009

Verification


Verification Process

Designed blocks in Behavioral Verilog to test design. After individual blocks simulated, top level control logic made to

test all pieces together. From Verilog design, built schematics for individual blocks. Tested individual blocks to determine functionality. After each block was confirmed worked, top level schematic tied

pieces together with control logic. Tested with multiple vectors to determine functionality.

1 ns clock Tested different functions, such as input budget, remove

item, writing to SRAM, etc.


Budget


Budget of $50 is input, converted to binary (110010), and stored in budget register shifted ten bits higher

December 2, 2009

SRAM


Wrote 5 values into SRAM

Values of bit and bit_bar are shown here as data is written.

December 2, 2009

SRAM


Arithmetic


Total goes over budget, over signal goes high

Remove item to send total back under budget

Addition: price of new items added to total

December 2, 2009

Layout Evolution


Initial Floorplan


Improved Floorplan


Final Layout

SRAMArithmetic: adder subtractor total register

Comparator

FSMs

control logic

Binary/BCD converters


Final LayoutTop Half


Final LayoutBottom Half


Design Specifications

Area ~ 56980μm2

370μm X 154μm Aspect Ratio: 1:2.4

Transistor count: 18532 Density: 0.32527 transistors/μm2


Retrospection

Overall the project was completed without too much difficulty or variance from the original plan.

The floorplan design changed significantly from the original version to the final layout. Had to account for 30-bit routing Some parts were deemed unnecessary

Issues with modelSIM made caused full structural verilog tests impossible Logic which looped onto itself had to be replaced with

behavioral verilog. Some library naming issues came up due to having to

share pieces between the three of us.


In Conclusion

Virtual Wallet provides a safe and secure way to increase shopping efficiency.

User is able to check out with Virtual Wallet when done shopping

Can be implemented in any store from large chains to mom and pop businesses.


Thank you

Questions/Comments?


virtual wallet

Documents

virtual walletdecember

virtual wallet30

virtual walletitem

online store database

online database

system descriptionslide

handheld system

accesses database