Homework 3: Design Constraint Analysis and Component Selection Rationale

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Nov 6, 2013 (3 years and 9 months ago)

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ECE 477

Digital Systems Senior Design Project

Rev 8/12

Homework
3
:
Design Constraint Analysis and Component Selection Rationale



Team Code Name: ____
MyATM
_______________________
_
_______

Group No.
___
5
__

Team Member Co
mpleting This Homework:
____
Tung Lun Loo
____________________

E
-
mail Address of
Team
Member: _____
tloo

@ purdue.edu



Evaluation:


SEC

DESCRIPTION

MAX

SCORE

1
.0

Introduction (including updated PSSC)

10


2
.0

Design Constraint Analysis


-


2.1


Computational Requirements

10


2.2


Interface Requirements

5


2.3


On
-
Chip
Peripheral Requirements

10


2.4


Off
-
Chip Peripheral Requirements

5


2.5


Power Constraints

5


2.6


Packaging Constraints

5


2.7


Cost Constraints

5


3.0

Component Selection Rationale

2
0


4.0

Summary

5


5.0

List of References

10


Ap
p

A

Parts List Spreadsheet

5


Ap
p

B

Updated Block Diagram

5



TOTAL

100




Comments:

Comments from the grader will be inserted here.


NOTE: This is the first in a series of four “professional component” homework assignments,
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-

灡来猬s
not

including this cover page,
references, attachments or appendices.

ECE 477

Digital Systems Senior Design Project

Rev 8/12


-
1
-

1.0

Introduction

A
n automated teller machine (ATM)

is a computerized device that

let

users
perform

financial

transaction
s

without the presence of a bank or a cash
i
er.

MyATM is another ATM that
supports the ba
sic ATM functionalities

with enhanced security
.
It

first detects a user

s presence
with an occupancy sensor,
reads the i
dentity of the user from
his/
her cash card
,
verifies the
identity of the user,

and
then
updates the user

s account information

in cash card

once the
transaction is done.
With improved security system
in mind, myATM

features face recognition
authentication technology (FRAT) along w
ith Personal Identity Number (PIN) authentication.
FRAT in myATM
is used

to login
to the user’s
account
, with
PIN number

acting as the

second
layer
of
account protection
.

Besides, myATM also
features
a
graphical user interface

that has

better user interactivity.
MyATM user can use touchpad

that supports gestures

to navigate
myATM

s menu and
select desired operation
s to
speed up the transaction

process.

M
yATM machine

are made out of eight main components
. They are the PIC18F24J11
microco
ntroller, Intel Atom Board,
2
web cameras
,

RFID
Reader

and Writer
, Occupancy
Sensor,
Speaker, Touchpad,
and Keypads.

The biggest constraints and challenges of building myATM
are the face recognition

algorithm

s

processing speed and accuracy.
When user

s
presence is

detected via the occupancy sensor, the
microcontroller will signal the Atom processor to start
capturing face images and processing them.
The
image

processing process should be less than a
few seconds

so that the login process is quick.

Another

constraint
comes from

the process of

updating

the

cash card

information to the server.

The cash card should be able to be read,
written
,

and
updated
.
Power and portability are not the major constraint of th
e

design since the ATM
machine will be
on
-
station.

Below are the PSSCs of the project:

1.

An ability to
use face recognition to verify the identity of the user

2.

An ability to use touchpad to
recognize gestures for menu navigation
.

3.

An ability to sense the presence of a user in front of ATM.

4
.

An ability to update the value
in

a cash card.

5.

An ability to
use keypad to
input numbers for PIN validation
and transaction
purposes
.





ECE 477

Digital Systems Senior Design Project

Rev 8/12


-
2
-

2.0

Design Constraint Analysis

There are several constraints to be considered when selecting components for myATM.

To
make the device feasible and
comparable with
current ATM system
s
,
it has to

be cheap
er than
the current ATM machine.
T
o enhance

the security

and
not delaying the login process, myATM
needs to be

able to fetch, compute and compare user images in a short
time

(Thus the processing
power of the motherboard

is important
)
. The microcontroller needs to have UART interface to
communicate with our motherboard, timers for sampling purposes and enough I/O pins for
keypad, PIR sensor, and RFID reader and writer.



2.1

Computation Requirements

The computational tasks are mostly handled by our motherboard. Those tasks includes



Run responsive GUI on the monitor



Detect user

s input from touchpad



Communicate with microcontroller

via
COM

port

(RS
232)



R
eceive RFID data,
occupancy sensor output and keypad input

from microcontroller



Capture multiple images frames using webcam



Process the images through face recognition algorithm



Upload the user cash card data
to the server



Output sound throu
gh audio jack

Based on the amount

of tasks and the need of speed for the applications, the board
needs to
have a processing
speed

of
around

1.6GHz,
512MB RAM

and supports hyper
-
threading
technology for parallel computing
. We have tested
a sample face recognition application
and
clarified
the requirement using

Intel

Atom N270

motherboard.

To utilize
Open
CV libraries,
plenty of RAM and storage will
also
be needed. In order to output a smooth and clear GUI on the
monitor, the screen will need to be refreshed at least 60Hz with a minimum resol
ution of
640x480.
For the purpose of supporting three RGB true
colors

in face recognition
, the webcam
needs to have

at least 24 bits

pixel quality
.
The images taken need to be
transferred

to the
motherboard at no less than 210
Mb/s to acquire m
ultiple frame
s in a short time. Another
requirement of the processing unit is to have
a way
to communicate with the microcontroller.

A
bidirectional serial port (in this case, UART to RS232)

with a transfer rate of up to 115Kbps
will
be sufficient for the
transferring

purpose
.



ECE 477

Digital Systems Senior Design Project

Rev 8/12


-
3
-

2.2

Interface Requirements

The microcontroller will

be communicating

with
the
Atom Board using
a
serial port
interface. Thus, a RS232 to UART adaptor will be used.

The microcontroller needs to have
at
least 1
3

digital input output

pins
.
7 digital I
/O
pins
are used
to sample

the keypad input
s
,

1

digital
I/O
pin

is

used on
the
PIR motion sensor
,
3 digital I/O pins

on

the

RFID Read Write Chip

and
a
few indicator LEDs
for debugging purposes

[7] [8] [9]
.

The Atom
Board

needs to support VG
A
connection

for the monitor
, RS232

for microcontroller
, 3

USB ports for 2 camera
s

and
a
touchpad, Ethernet

for the server

connection
,
and audio jack for the speaker.


2.3

On
-
Chip
Peripheral Requirements

The microcontroller needs to have at least 3 timers for RFID data, k
eypad inputs and PIR
motion sensor. The first

timer channel is required to sample the incoming RFID data
from RFID
cash card

to microcontroller

at every fixed interval.

Since the RFID card reading and writing
operation are not performed at the same time, t
he same timer
can be

used to
write RFID data

from the microcontroller

to the
RFID
transponder

(
cash
card
)
.
The s
econd timer channel
is used
to sample the keypad input
s

while the t
hird timer
is
used
to sample the pulse
s

from the
occupancy

sensor
at

certain
interval
s

to
determine the presence of us
er in front of
myATM
.

Besides, a

UART interface is required for microcontroller to communicate with

the

Intel
Atom Development Board. Input signals from the keypad will be transmitted to the

microcontr
oller and then

to the Atom board

so that
the system
can validate user
-
in
put PIN.
In
addition, user profile da
ta will be received and

transmitted via RFID interface.
After that, it will
be sent to

microcontroller and
then to the motherboard
via UART

to be further updated

in the
server
.

In short, the microcontroller in myATM n
eed
s

at least 3 channels

of 8
-
bit or 16
-
bit timers
and
a

UART interface.


2.4

Off
-
Chip Peripheral Requirements

The off
-
chip peripheral required are
an
RFID base reader

and
writer
,
a
RS
-
232 level
translator

and
a
5V to 3.3V level translator
.

The
RFID base reader and writer

chip

is

used to read
and write to the
RFID tag
.
The IC
needs to be able to be

configured
dynamically
using
microcontroller
to read from or write on
an RFID tag
. The RS
-
232 level
translator translates
ECE 477

Digital Systems Senior Design Project

Rev 8/12


-
4
-

UART signals to RS
-
232 signals to communicate with
the
Atom
Board.

On the other hand,
5V
to 3.3V level translator

is used

for sending signals to RFID base reader

and
writer by the
microcontroller
since
the
micro
controller runs on
3.3V logic

and

the
RFID base

reader and writer
runs
on

5V logic
.

[
9]


2.5

Power Constraints

Since the proje
ct is an on
-
station device,
minimal power consumption is a plus point but not
a necessity.
We will ac
quire A.C power to
power the

Intel Atom
Boa
rd, LCD monitor screen,
and
the
custom
-
made PCB.
Therefore, it is not a portable d
evice and it has to be available only

in
place where A.C power is
accessi
ble.


2.6

Packaging Constraints

The packaging will need to be tough and able to fit the parts reasonably
.
Therefore we are
looking at using wood casing to put our electronics part
. Considering the fact that the standard
ATMs are 56


Height

[1]
, we a
re implementing the same
height

for standard adults.
The
stereo

cameras will be placed at
a height of
53


where it should be able to capture
the
user

s face
.


2.7

Cost Constraints

T
he current ATM machine
s are

price
d

at approximately $1800

[1]
. Considering the fact that
the ATMs on the market
include

robust cover, printer,
cash

locker and
cash
dispensing part, the
price is no d
oubt higher. Therefore, we
are targeting

below $500 for our electronic design so
that we have another $1300 for the
implementation of covers
.


3.0

Component Selection Rationale

The microcontroller choices are narrowed down to PIC and ATmega

due to the project
constraints, availability of development board, and familiarity of the microcontroller
environment.

Initially we
choose

the
PIC32MX110F016D

[2]

microcontroller because it
supports full speed USB 2.0 connection to interface with the moth
erboard. However, after
gathering feedbacks
from

our
design constraint presentation, we decided to go with serial
communication interface instead of USB interf
ace. Thus,

our choices re
volve

around
PIC18F24J11 and AT90PWM2B.
PIC18F24J11
[3]

has 28 pins, thre
e 16
-
bits timer,

and
two
ECE 477

Digital Systems Senior Design Project

Rev 8/12


-
5
-

enhanced USART modules that
support

RS
-
232. On the other hand, AT90PWM2B
[4]

features
24 pins,
three

8
-
bit tim
er
s
,
and supports UART.

Thus, t
hey
have

fulfilled

the
requirement
s

for

the design, which
is

3 timers, sup
port UART, and
have more than 1
3

digital I/O pins. We

decided to choose PIC18F24J11 b
ecause

the

TAs suggested that PIC
microcontrollers
have less
problems in external circuitry compared

to other microcontroller famil
ies
.

There are many options our group has considered
for the single board computers such as
Intel

Atom Board,
Beagle Board
,

and
Raspberry Pi
. Raspberry Pi is not available to be delivered
in a short time

so it is eliminated from
our

options.

We are looking at choosing between Intel
Atom N270 and BeagleBoard
-
xM
. Atom N270 features single core Atom processor running
1.6GHz, 512MB RAM, supports Hyper
-
Threading Technology, have 3 USB ports, 10/100
Ethernet, RS232 and VGA

[5]

while BeagleBoard
-
xM runs ARM Cortex A8 at 1GHz, 512MB
RAM, 4 USB port, DVI, 10/100 Ether
net

and RS232

[6]
.

Between Intel Atom
Family and ARM
Boards,

Atom

is more preferable

because x86

instructions works better with
most Linux Distro

compared to

ARM architecture.
We

choose
to install
Linux is because it is open source and

supports
a lot of

face recognition libraries
.

Since Atom N270 is readily available in lab, w
e were
given
the board

to test
available
face recognition algorithm
s
. Since
it works
with
the sample
programs without much lags,
we decided to stick with

the

Intel Atom N270

for our

project.


4.0

Summary

There are many design constraints in myATM that need to be considered when making a
decision on parts. The
focus on security instead of mobility in the design leads

us to a direction
of choosing high processing power development board i
nstead of low power consumption parts.
The microcontroller is used more on fetching user inputs such as RFID card info, keypad input
s
,
and occupancy sensor output. Thus
adequate
pin counts

(1
3
)
, features and peripherals are needed
for our

microcontroller.
We have chosen Intel Atom N270 for the processing power
and RAM
for the face recognition algorithm
and PIC18F24J11

microcontroller

for the simplicity, price and
matching of

our
constraints
.

We believe our design will make full use of the parts we choose
in
stead of
over killing

or under powering

the parts.

ECE 477

Digital Systems Senior Design Project

Rev 8/12


-
6
-

5.0
List of References


[1]

EmpireATM,

Our Products: ATM Machines

, 2013, [Online]. Available:
http://empireatms.com/products.html


[2]

MicroChip,

PIC32MX1XX/2XX

, 2009, [Datasheet]. Available:
http://www.mouser.com/ds/2/268/61168D
-
78803.pdf



[3]

MicroChip,

PIC18F2XJxx Family

, 2009, [Datasheet]. Available:
http://www.mouser.com/ds/2/268/39687e
-
62060.pdf



[4]

ATMEL,

8
-
bit AVR Microcontroller with 8K Bytes In System Programmable Fla
sh

,
2010, [Datasheet]. Available:
http://www.mouser.com/ds/2/36/doc4317
-
46744.pdf



[5]

Intel,

Intel Atom Processor N270

, [Online]. Available:
http://ark.intel.com/products/36331/Intel
-
Atom
-
Processor
-
N270
-
512K
-
Cache
-
1_60
-
GHz
-
533
-
MHz
-
FSB#iid=2524



[6]

Beagle
Board,

BeagleBoard
-
xM Product Detail

, Jun 01, 2011, [Online]. Available:
http://beagleboard.
org/hardware
-
xM



[7]

Keypad
,

SERIES 96 Conductive Rubber

, 2010,

[Online]. Available:
http://media.digikey.com/pdf/Data%20Sheets/Grayhill%20PDFs/96%20Series.pdf


[8]

PIR
sensor
,

EKMC Standard Profile (170 uA)

, 2009, [Online].

Available
:

http://pewa.panasonic.com/assets/pcsd/catalog/papirs
-
ekmc
-
catalog.pdf


[9]

RFID Base Station
,

Communicating with RFID Base Station

,
2009
,

[Online]. Available:
http://www.ti.com/lit/an/swra283/swra283.pdf

















IMPORTANT: Use standard IEEE format for references, and CITE ALL REFERENCES
listed in the body of your
report
.

ECE 477

Digital Systems Senior Design Project

8/12


-
7
-

Appendix A: Parts List Spreadsheet



Vendor

Manufacturer

Part No.

Description

Unit Cost

Qty

Total Cost

Digi
-
Key

Microchip

PIC18F24J11
-
I/SO

Microcontroller

2.94

1

$2.94

Digi
-
Key

Grayhill Inc

96AB2
-
102
-
F

4x3 keypad

14.20

1

$14.20

Digi
-
Key

Atmel

U2270B
-
MFPY

RFID R/W base station

3.01

1

$3.01

Digi
-
Key

Atmel

ATA5577M1330C
-
PP

RFID transponder/tag

3.44

1

$3.44

Digi
-
Key

Panasonic

EKMC1601112

PIR motion sensor

10.26

1

$10.26

Amazon

Ergonomic
Touchpad

The Ergonomic
Touchpad

USB touchpad

36.95

1

$36.95

Mouser

Maxim Integrated

MAX3373EEKA+T

5V to 3.3V
voltage level translator

2.30

1

$2.30

Mouser

Texas Instruments

LM2675M
-
5.0/NOPB

5V, 1A switching regulator

3.60

1

$3.60

Mouser

Texas Instruments

LM2675M
-
3.3
/NOPB

3.3V, 1A switching regulator

3.60

1

$3.60

Mouser

Maxim Integrated

MAX3232CAE+

RS
-
232 level
translator

4.62

1

$4.62

Amazon

Logitech

960
-
000162

Logitech QuickCam Messenger

7.23

2

14.46

TOTAL

$
99.38

ECE 477

Digital Systems Senior Design Project

8/12


-
8
-

Appendix
B
:
Updated Block Diagram