Express
Aisle
Alicia Dail and Edward Giardina
University of Rhode Island
ELE408 – Computer Organization
May 1, 2001
T A B L E O F C O N T E N T S
Introduction 3
Serial
Communications 4
Flowcharts 5
Optimistic System Flowchart 5
Optimistic Scan and Interrupt Routine
Flowcharts 6
Realistic System Flowchart 7
Realistic Scan and Interrupt Routine
Flowcharts 8
Constraints 9
Economic 9
Manufacturability, Modularity and
Expandability 9
Social and Political Constraints 10
Health and Safety Constraints 10
Ethical Constraints 10
Results/Conclusion 11
Future
Improvements 12
Assembly
Source Code A1
Sample
Output B1
Barcodes C1
IEEE
Code of Ethics D1
INTRODUCTION
Express Aisle is a simulation of the realistic setting of cashing out at a retail store, such as Shaws. Express Aisle is a practical application that can be used by any store that sells products that have barcodes associated to their prices. Like most businesses that use hand-held barcode scanners, the user has the ability to scan UPCs and compute the total amount due for the products purchased.
The design required the use
of both UARTs in order to communicate serially with the hand-held barcode
scanner and the HyperTerminal display. All scanned prices are displayed on the
computer as they are scanned. After the
user scans the end of transaction barcode, the program will display the total
amount due.
SERIAL COMMUNICATIONS
Motorola ColdFire
5307
· UART – COM1
· 19200 bPS
· Controls Display
NipponDenso
· UART – COM2
· 19200 bPS
· Controls hand-held scanner
OPTIMISTIC SYSTEM FLOWCHART
Originally, it was the hope
that the user would be able to keep scanning barcodes until the
‘Enter’ key on the keyboard was pressed to signify
the end of the transaction. Meanwhile,
each time a barcode was scanned the price would be added to the subtotal.
OPTIMISTIC SCAN AND INTERRUPT ROUTINES
Originally, a 7% RI sales tax was supposed to be
added to the subtotal to produce the total amount due.
REALISTIC SYSTEM FLOWCHART
In reality the user will be able to scan barcodes continuously
until an End of Transaction barcode is scanned.
REALISTIC SCAN AND INTERRUPT ROUTINE
There was no sales tax added
to the subtotal because we had problems displayed the correct total of
purchases.
CONSTRAINTS
Economic Constraints:
When looking at the performance/cost ratio
for an application such as this, one should consider the differences between
serial and parallel communication.
Communication using the serial port is a little slower than parallel
because serial communication involves control handshaking, such as receiver
ready; while the parallel port has no status registers associated with it, thus
the user need only write/read data to/from a data line.
Although serial
communication is slower, it is also cheaper. This is due to the fact that
serial communication is transmitted over only 1 channel; while on the other
hand, parallel communication uses an individual wire for each channel that the
system is communicating over. So
obviously for parallel communications, the more channels that are needed,
requires more individual wires, which means more money. Also, the serial port is easier to program
and of more value than the parallel port for an application such as this. The time saved in development time saves money
in the cost of production.
When weighing performance versus cost, serial communication saves more money comparatively to the better performance of parallel communication.
Manufacturability, Modularity and Expandability
Constraints:
This program was written with some regard for
modularity. Unfortunately, there were
times when we lacked the resources to form modular subroutines. With a few additional data registers, we could
have had loops based on counts to perform similar blocks of code.
This application could definitely be further expanded. One idea would be to have variable barcodes that would be associated with a product name, price, and possibly a taxable amount.
This
application can be readily manufactured in mass quantities because it only
requires a copy of the software and a hand-held scanner.
Social and Political Constraints:
This project could be of social impact. Although the hand-held scanner has been
around for quite some years now, when it first came out it made an impact on industry. Imagine going to Stop & Shop and having
to type each individual price into the computer. This could take a long time.
The hand-held scanner has drastically changed the way we check out at
the register. It allows customers to
cash out quickly and effectively.
Health and Safety Constraints:
Health and safety constraints are minimal in
this project. In the real world, this
project would be used only in the retail industry. This is of no importance to national security, but we should
consider the importance of associating the price encoded in the barcode with
the scanned product. An incorrect price
could either upset a customer or cause the store to lose money. In terms of users physical health, the
hand-held scanner should not be pointed in anyone’s eyes because the infra red
light can be harmful to the eyes.
Ethical Constraints:
All project goals were not achieved, but are
well documented throughout the paper.
We do not wish to project false output.
All sample and future output produced will accurately reflect program
execution in accordance with the IEEE Code of Ethics. See Appendix D for a copy of the IEEE Code of Ethics with a
signed statement to the effect that we followed the code.
RESULTS and CONCLUSIONS
The scanner is fully functional. The price is correctly displayed for each barcode scanned. The prices are summed up, but although the prices are in their BCDs, the add command adds them as though they are hexadecimal. Therefore the total is the correct hexadecimal value, but the incorrect monetary value. But it may sound as simple as doing a BCD conversion on the sum, but this is not the case. In order for the correct sum to be displayed, each digit of the price would have to be individually added to the corresponding subtotal digit. Then this solution could be converted to its BCD and the remainder added to the next digit. Due to time constraints we were not able to implement this technique adequately. So we have left our output as its hexadecimal sum.
Due to the amount of time spent on displaying the subtotal we were unable to implement a functional interrupt routine. Instead we implemented a check for an End of Transaction barcode in order to end program execution.
FUTURE IMPROVEMENTS
·
In the future, it is important to be able to rectify the subtotal
display situation. Through the use of the technique mentioned above, we could
potentially fix the subtotal display with some more development time and
aggravation.
·
A state tax could be introduced.
·
An interrupt should be added to trigger the End of Transaction.
SOURCE CODE
*****************************************************************************
UCR2=0x10000208 |UART 2 Command register
UMR12=0x10000200 |UMR mode register
UMR22=0x10000200 |UMR mode register
USR2=0x10000204 |Status Register
UCSR2=0x10000204 |Clock Select register
URB2=0x1000020c |Receiver buffer
UTB2=0x1000020c |Transmitter buffer
UBG12=0x10000218 |Baud Rate Generator MSB
UBG22=0x1000021c |Baud Rate Generator LSB
UIVR2=0x10000230 |Interrupt Vector Register
move.l #0x10000000,%d0
move.l %d0,MBAR |initialize MBAR
move.l #0,%a6
move.l %a6,VBR |initialize vector base register
move.l #0x1000c040,%d0
move.l %d0,ACR0
move.l #0x80008000,%d0
move.l %d0,CACR
move.l #0x2021C,%d0
move.l %d0,0x0100
move.b #0x20,%d0 |UART 2 receiver reset
move.b %d0,UCR2
move.b #0x30,%d0 |UART 2 transmitter reset
move.b %d0,UCR2
move.b #0x10,%d0 |UART 2 register reset
move.b %d0,UCR2
move.b #0xB3,%D0 |set up the UMR1 (UART1 mode register)
move.b %D0,UMR12 |see pg 14-18,19 of the users manual
move.b #0x07,%D0 |set up the UMR2 (UART1 mode register)
move.b %D0,UMR22 |see pg 14-20,21 of the users manual
move.b #0xDD,%D0 |select timer mode as the Tx/Rx clocking
move.b %D0,UCSR2 |see pg 14-24 of the users manual
move.b #0x00,%D0 |Disable interrupts for the COS&/CTS
move.b %D0,UACR2 |see pg 14-30 of the users manual
move.b #0x02,%D0 |Interrupt only when FIFO is full
move.b %D0,UIMR2 |see pg 14-31 of the users manual
move.b #65,%D0 |Interrupt vector set to 65
move.b %D0,UIVR2 |see pg 14-33 of the users manual
|65 was a random choice.
|65 decimal is converted by the processor
|to the vector offset hex value of 0x104
move.b #0x00,%D0 |Set baud rate to 9600 (45 mhz clk)
move.b %D0,UBG12 |see pg 14-32 of the users manual
move.b #0x92,%D0
move.b %D0,UBG22
move.l #0x50000,%a0
move.l #0x30000,%a1
move.l #0x40000,%a5
MOVE.L #0x30,%D3
CLR.L %D6 | individual price
CLR.L %D7 | subtotal
scan: clr.l %d0 |Clear Registers
clr.l %d1
clr.l %d2
move.b #0x09,%d0 |Enable the receiver and disable the transmitter
move.b %d0,UCR2
start: move.b USR2,%d1 |has a character been received?
btst #0,%d1
nop
beq start
CLR.L %D6
move.b URB2,%d1 |load the char into receiver buffer
move.b %d1,%d2
cmp.l #0x30,%d2
beq display
move.b #0x24,%d1 | Load $
move.l #0x0013,%d0 | display the $
trap #15
move.b %d2,%d1
move.l #0x0013,%d0 |display the char in the screen
trap #15
MOVE.B %D1,%D6 | shift digit into price register
SUB.L %d3,%d6
dollars: move.b USR2,%d1 |has a character been received?
btst #0,%d1
nop
beq dollars
move.b URB2,%d1 |load the char into receiver buffer
move.l #0x0013,%d0 |display the char in the screen
trap #15
cmp.l #0x2e,%d1 | stay in this loop until a decimal point is found
beq tenth
LSL.L #4,%D6 | shift price register
add.l %D1,%D6
sub.l %D3,%D6
bra dollars
tenth: nop
move.b USR2,%d1 |has a character been received?
btst #0,%d1
nop
beq tenth
move.b URB2,%d1 |load the char into receiver buffer
move.l #0x0013,%d0 |display the char in the screen
trap #15
LSL.L #4,%D6 | shift price register
add.l %D1,%D6
sub.l %D3,%D6
hundredth: nop
move.b USR2,%d1 |has a character been received?
btst #0,%d1
nop
beq hundredth
move.b URB2,%d1 |load the char into receiver buffer
move.l #0x0013,%d0 |display the char in the screen
trap #15
LSL.L #4,%D6 | shift price register
add.l %D1,%D6
sub.l %D3,%D6
move.l #0x0a,%d1 | To output 1 line feed
move.l #0x0013,%d0
trap #15
move.l #0x0d,%d1 | To output 1 carriage return
move.l #0x0013,%d0
trap #15
eol: move.b USR2,%d1 |has a character been received?
btst #0,%d1
nop
beq eol
move.b URB2,%d1 |load the char into receiver buffer
move.l #0x0013,%d0 |display the char in the screen
trap #15
nop
BCDconvert:
ADD.L %D6,%D7
CLR.L %D6
clr.l %d4
move.l #0x0a,%d4
CLR.L %D5
move.l %D7,%D5
and.l #0x000f,%d5
DIVU.L %D5,%d4 | get BCD
move.w %D5,%D4 | BCD
lsr.l #0x08,%d5 | get remainder
MOVE.B %D4,(%A5)+ | pennies
move.b %d5,%d4 |remainder
move.l %D7,%D5
LSR.L #4,%D5
and.l #0x000f,%d5
ADD.L %d4,%D5
move.l #0x0a,%d4
DIVU.L %D5,%d4 | get BCD
move.w %D5,%D4 | BCD
lsr.l #0x08,%d5 | get remainder
MOVE.B %D4,(%A5)+ | dimes
move.w %d5,%d4 |remainder
move.L %D7,%D5
LSR.L #8,%D5
and.l #0x000f,%d5
ADD.L %d4,%D5
move.l #0x0a,%d4
DIVU.L %D5,%d4 | get BCD
move.w %D5,%D4 | BCD
lsr.l #0x08,%d5 | get remainder
MOVE.B %D4,(%A5)+ | ones
bra scan
display:
move.l #7,%d4
dash:
move.l #0x2d,%d1 |Load -
move.l #0x0013,%d0 | display the -
trap #15
sub.l #1,%d4
bne dash
move.l #0x0a,%d1 | To output 1 line feed
move.l #0x0013,%d0
trap #15
move.l #0x0d,%d1 | To output 1 carriage return
move.l #0x0013,%d0
trap #15
MOVE.L #0x30,%D3
move.b #0x24,%d1 | Load $
move.l #0x0013,%d0 | display the $
trap #15
clr.l %d5
move.b -(%A5),%D5
ADD.L %D3,%D5
MOVE.B %D5,%D1 | get next digit
move.l #0x0013,%d0 | display the digit
trap #15
move.b #0x2E,%d1 | Load .
move.l #0x0013,%d0 | display the .
trap #15
clr.l %d5
move.b -(%A5),%D5
ADD.L %D3,%D5
MOVE.B %D5,%D1 | get digit
move.l #0x0013,%d0 | display the digit
trap #15
clr.l %d5
move.b -(%A5),%D5
ADD.L %D3,%D5
MOVE.B %D5,%D1 | get digit
move.l #0x0013,%d0 | display the digit
trap #15
move.l #0x0a,%d1 | To output 1 line feed
move.l #0x0013,%d0
trap #15
move.l #0x0d,%d1 | To output 1 carriage return
move.l #0x0013,%d0
trap #15
bra finish
_UARTInterrupt:
move.l %d0,-(%a7)
clr.l %d0
move.b USR2,%d0
btst #0,%d0
beq trans
move.b URB2,%d0
move.b %d0,(%a1)+
trans:
move.l (%a7)+,%d0
finish:
trap #15
******************************************************************************************
SAMPLE OUTPUT
S-record
download successful!
dBUG>
go 20000
$2.99
$1.59
$1.29
$2.29
-------
$7.44
dBUG>
go 20000
$1.99
$1.79
-------
$3.12
dBUG>
go 20000
$1.79
$2.09
-------
$3.82
dBUG>
BARCODES
