WEST VIRGINIA UNIVERSITY
Department of Computer Science and Electrical Engineering
MICROPROCESSOR SYSTEMS LABORATORY
FINAL PROJECT
CPE 311
Fall 2001
Coliseum intersection
Introduction:
The purpose of this project is to build a model of an intersection similar to the intersection beside
the Coliseum. Red, yellow, and green LED's will be used to represent the traffic lights. The keyboard will be
used to simulate car detector sensors. DIP switches will be used to choose such modes of operation as
normal and emergency. Additionally, an LCD must be interfaced with the controller system, which will
display status messages and state of the car detector sensors. You will use the Octagon SBC and write an
assembly language program to control the "intersection" and interact with the inputs and outputs of the
system. This project will require that you design the both the software and the hardware for the Octagon to
control all of the traffic lights from the limited number of input/output pins available.
Project details:
The attached figure shows the general description of the traffic light. There are 8 traffic lanes:
North-South (NS), South-North (SN), East-West (EW), West-East (WE), North-South Left Turn (NSL),
South-North Left Turn (SNL), East-West Left Turn (EWL) and West-East Left Turn (WEL). Each lane has
its own traffic sensor (a device that detects presence of a car). You should use the keyboard to represent the
binary output from the sensors (1 – there is a car, 0 – no car). Each sensor should be assigned its own key,
the state of the sensor should be toggled by pressing that key.
You must also include a set of DIP switches that will specify the mode of operations. DIP switch 1
sets the normal mode of operation. DIP switch 2 sets emergency NS mode of operation (flashing yellow on
N and S lanes, flashing red on E and W lanes). DIP switch 3 sets emergency EW mode of operation
(flashing yellow on E and W lanes, flashing red on N and S lanes). Any invalid combination of the switches
should turn on the fail-safe mode (all lights blinking red).
In the normal mode, the operation of the traffic light is very straightforward, you may use your
observations of the real intersection and make reasonable modifications in the design (confirm with your
instructor before making any change and document the changes in the report!). The goal is to optimize
traffic flow through the intersection:
- You may open either NS and SN lanes or EW and WE lanes together
- You may open either NSL and SNL or EWL and WEL lanes together
- Decisions about opening the lanes should be based on the values from the traffic sensors
- You may open NS and NSL lanes together if SN and SNL have no cars (the same is true for the
rest of the directions)
- The minimum time a light can be on is 10sec (except yellow – 5sec)
Finally, you have to reflect the status of the intersection on the LCD. The top line of the LCD should
contain the status: normal, emergency NS/EW or fail-safe. The bottom line should show the open lanes by
the abbreviations.
Design problems:
-
-
-
The SBC has 24 input/output lines. You must interface 8 lines to the LCD, 3 lines for the DIP
switches and 20 LEDs for the traffic lights. You will need to design additional hardware that
will let you operate only with the available lines.
Modularization of the program. Implementing a large project in just one routine is very
complex. You should split the project into a set of subroutines that can be independently
designed and debugged.
Control algorithm. Before the control program can be written, you must have a clear
understanding of how it will work.
Keeping track of time.
Report:
After successful demonstration of your final project your lab report should contain:
- General description of your program
- Block-diagram of the control algorithm
- Circuit diagram
- Fully commented source code
Grading:
Each part of the assignment has its weight, based on the progress in the design:
1.
2.
3.
4.
5.
6.
Hardware interfacing (10pts)
Working dumb traffic light in normal mode (no sensors, switches, etc.) (20pts)
Working traffic sensors (smart traffic light) (20pts)
Working emergency modes switches including fail-safe (20pts)
Working LCD output (20pts)
User interface (10pts)
The credit is given only for the parts of the project that work and properly interact with other parts.
The assignment will be graded based on the following criteria, applied individually to each part of
the assignment:
Grading table for parts 1-6 (each part is graded separately).
Weight
35%
A Excellent
Comments on
the source code
35%
Documentation
and Report
30%
Clear
comments
explaining
logic structure
of the program
and meaning of
each important
instruction.
Clear, excellent
organization,
well
documented,
and neat. ,
Clearly
explains the
algorithms and
implementation
details.
Hardware and
circuit diagram
or source code
Correct circuit
diagram with
all necessary
calculations.
Correct source
code with no
hidden errors.
C Average
D Fair
F Poor
Incomplete but
correct circuit
diagram. Minor
errors in the
code (that
appear only
under certain
conditions,
without creating
a dangerous
situation of the
intersection)
Good comments
but not always
clear
B Good
No more that one
major error in the
circuit diagram or
assembly code. (The
project must work,
but the functionality
is different from the
one specified in the
assigment. The error
must not create a
dangerous situation
on the intersection)
Misleading
comments.
Comments that do
not explain how the
program functions.
More that
one major
error. An
error that
creates a
safety
hazard.
Not
working.
Comments
do exist in
the code.
No
comments or
excessively
poor
comments
Good
organization but
not always clear
that writer
understands the
solution. Minor
details are
missing.
OK organization,
documentation
somewhat confused.
Gaps in description
of algorithms and
implementation.
Poorly
organized,
hand written,
poorly put
together.
Poor, patchy
descriptions.
No
organization.
No
descriptions.
User interface grading table (part 8)
User interface
A
The hardware
assembly is neat and
easy to observe and
understand. The
software interface is
clear and
understandable, with
proper instructions
displayed on the
screen.
B
Not so clear,
partially missing
operating
instructions or
somewhat
troublesome
hardware.
C
The user have to
guess what this
LED shows or
what that button
does (but it
works).
D
Partially
working user
interface.
F
Nothing to
show.
N
S
G
Y
R
S
GY
R Y G S
W
GY S
S G Y R
S GY
S
S
R
G
R
G
GY
S
S
Traffic light (Red, Yellow or Green)
Traffic Sensor
Pedestrian crossing switch
Figure 1. The intersection
R
Y
G
S
E