EAT237 SEGi College Sunderland Microprocessor Project: Landmark

This document contains two assignments related to Microprocessor and PLC concepts. The first assignment focuses on designing a famous landmark display using low-level programming of a 68k-based microprocessor system. It involves creating a flowchart, breaking it down into assembly instructions, and displaying the output. The second assignment involves designing a PLC-based plant factory controller to optimize environmental conditions for tomato growth. This includes researching optimal growth conditions, designing a control system, selecting components, developing PLC programs, and evaluating the system's performance. The controller uses sensors to monitor temperature and humidity, and actuators to adjust fan speed, direction, and tower light indicators to maintain the desired conditions for tomato cultivation.

SEGi College Subang Jaya
In Collaboration with University of Sunderland, UK
B.ENG (HONS) ELECTRONIC & ELECTRICAL ENGINEERING
EAT237
Microprocessor and PLC
ASSIGNMENT 1 (15%) - Individual
TITLE :
Famous Landmark Display
Name:
UOS ID : SCM ID:
Lecturer:
Submission Form Hardcopy: Yes/ No Softcopy: Yes/No
Declaration :
I declare that this material, which I now submit for assessment, is entirely my own work
and has not been taken from the work of others, save and to the extent that such work has
been cited and acknowledged within the text of my work. I understand that plagiarism,
collusion, and copying are serious in the university and accept the penalties that would be
imposed should I engage in plagiarism, collusion or copying.
Signature : Date :
Objective:

To construct a design using the low level programming of microprocessor
68k based system
Procedures:
A small flowchart for solving the assignment is framed before writing a program. This
flowchart is broken down into smaller instructions and then mapped out to individual
instructions or group of instructions in assembly.
Output Display:
Program 1.a
Program 1.b

Program 1.c
Discussion: The assembler is 32 bit data registers. Characters are represented using
ASCII notation occupying single byte. This required use of .B specifier after MOV
instructions for correct operation of program.
Conclusion: The memory indexing options in the processor are really efficient for
accessing memory elements when working with number arrays or string arrays..

Assignment 1 Marking Scheme
TERIA 1
Beginning or
incomplete
2
Developing
3
Accomplished
4
Exemplary
mental
ure
Missing several
important experimental
details or not written in
numbering format.
Written in numbering
format, still missing
some important
experimental details.
Written in numbering
format, important
experimental details are
covered, some minor
details missing.
Well-written in numbering
format, all experimental
details are covered
s:
t Display
Display contain errors or
are poorly constructed.
Result is displayed, some
still missing some
important or required
features.
Display is correctly
designed, no errors, but
could still be mproved.
Display is creatively
designed, well structured.
sion Very incomplete or
incorrect interpretation
of knowledge and
comparison of data
indicating a lack of
understanding of result.
The result has been
correctly interpreted and
discussed; partial but
incomplete
understanding of results
is still evident.
The result has been
correctly interpreted and
discussed, only minor
improvements are needed.
Result has been interpreted
correctly and discussed,
good understanding of
results is conveyed.
usions Conclusions missing or
missing the important
points.
Conclusions regarding
major points are drawn,
but many are misstated,
indicating a lack of
understanding.
All important conclusions
have been drawn, could be
better stated.
All important conclusions
have been clearly made,
student shows good
understanding
g,
mar,
ce
ure
Frequent grammar and/or
spelling errors, writing
style is rough and
immature
Occasional
grammar/spelling errors,
generally readable with
some rough spots in
writing style
Less than 3
grammar/spelling errors,
mature, readable style
All grammar/spelling
correct and very well-
written
rance and
ting
Sections out of order, do
not adhered to the format
given, poor formatting.
Sections in order,
contains little
requirement of the
formatting , rough
structure but readable
All sections in order,
formatting generally good
but could still be improved
All sections in order, well-
formatted, very readable
ARK (if any):
TOTAL (max 24 marks)

SEGi College Subang Jaya
In Collaboration with University of Sunderland, UK
B.ENG (HONS) ELECTRONIC & ELECTRICAL ENGINEERING
EAT237
Microprocessor and PLC
ASSIGNMENT 2 (35%) - Group
TITLE :
PLC Programming for practical application
Group Leader:
Team Members: 1)
2)
3)
Lecturer:
Submission Form Hardcopy: Yes/ No Softcopy: Yes/No
Declaration :
We declare that this material, which we now submit for assessment, is entirely our own
work and has not been taken from the work of others, save and to the extent that such work
has been cited and acknowledged within the text of our work. We understand that
plagiarism, collusion, and copying are serious in the university and accept the penalties that
would be imposed should we engage in plagiarism, collusion or copying.
Signature of Group Leader: ___________________ Date: ____________________

Objectives:
The objective is to design a plant factory controller so as to optimise the environmental
conditions and promote the growth of tomatoes within the facility. The controller is expected
to affect actuators so as to maintain the required ambient temperature and humidity. The
controller make decision depending upon the end product received from the sensors install it
with its locations within the facility achieve these objectives we need to achieve following
smaller milestones in the sequence as mentioned
1) Refer to research in agricultural production practices and determine the
optimum conditions for the growing of tomatoes
2) Design a system specification for the control system to provide optimum
growth conditions at the farm
3) Select most effective components needed to implement this system
4) Develop required programmes for system controller
5) A comparative evaluation of the developed systems
Completion of above listed milestones will help us design a system that is capable of
delivering the required output and maintain the growth parameters to the maximum efficiency
level within the facility.
Procedures:
i. The first step to achieve the objectives is to study the growth pattern of tomatoes
and its growth cycle. The required environmental free parameters like temperature
humidity soil temperature and light conditions.
ii. Study different kind of sensors and actuators, list their operating range and their
working conditions. This shall help choose the best possible device options for
input sensors and output actuators.
iii. Work through the voltage and current ratings for the sensors and microcontrollers
and develop interfaces.
iv. Create software program for the PLC or the microcontroller and test out the
design after interfacing the required sensors in the controlled test environment
v. Optimize the design and the program to work efficiently for long working hours
during different times of day and night.
vi. Install the design in test facility and monitor the results for possible duration.
Flowchart:
Flowchart for the program to control the system parameters.
i. Read Temperature sensors

ii. Read humidity sensors
iii. Compare the measurements and provide indications using Tower light. Adjust
Fan speed and direction as per readings
iv. If Temp 22-28, Humidity 60%-80%: Tower Light Green; Fan off
v. If Temp < 22 or Humidity < 50% ; Tower Lights Orange: Fan on : inflow
vi. If Temp > 30 or Humidity > 80% ; Tower Light Oraange: Fan on: outflow
vii. If Temp < 15 or Humidity < 25%; Tower Light Red; Fan on : inflow
viii. If Temp > 40 or Humidity > 85%; Tower Light Red; Fan on : outflow
ix. Loop
Discussion:
Research about the operations of a plant and collect information about process of growth of
tomatoes in a closed environment. This is followed by selection of sensors required to capture
the required parameters. Once sensors are attached to the controller, their readings can be
used to affect the conditions of the plant using suitable systems. This will involve use of
actuators to activate mechanism installed in the facility for temperature control, humidity
control and other environmental conditions as necessary to promote growth of the tomato
plants.
i. Research to determine the optimum conditions for the growing of tomatoes and the use of
this information to determine the specifications for the control system. Plant factory is
concept to mechanize the farming process so that products can be grown in controlled
environment irrespective of climate and region. This involves being able to control factors
like light intensity, air temperature, air humidity, mineral nutrition, water flow etc. to an
optimal level and promote growth of crops. The central control system at the facility
controls the heater, fan, water pump, and nutrient solution and humidifier actuators as per
feedback from sensors in real time.
A threshold needs to be set for the actuators to be fired for certain duration. The threshold
decision is based on values read by sensors deployed at the plant. For a tomato plantation
various studies have been conducted. The plant growth is divided into 5 stages. Time for
first fruition depends upon the variety of the plant but mostly fall in the range of 70-80
days. Expected temperature for the plants also depends upon their growth stage but a usual
22-25⁰C range is considered conducive to growth. Next important parameter is humidity.
There are three ways it is measured in terms of absolute humidity, specific humidity and
relative humidity. Out of these relative humidity is most commonly used term of

measurement. The humidity range between 60-90% is considered appropriate for growth
of the tomato plants in a closed environment.
ii. A selection process to determine the most appropriate components for such a system. The
system shall require two types of sensors to measure temperature and humidity. Some kind
of actuators would be needed to activate fan and control fan direction. Another set of
actuators would be required to toggle between Tower light colors.
Sensors are device that measure a physical measureable quantity and provide an
equivalent value as an electrical signal directly proportional to the value being measured.
The sensors ability to measure smallest change is called its resolution and ability to
measure the smallest possible and largest possible temperatures is called its range.
Sometimes the measurements are in form of continuous or analog signals and sometimes
as digital discrete signals. The one we choose depends up on the interface being used in
the design and capability of the controller.
We need two types of sensors that measure temperature and humidity. The sensors must
provide this input to the microcontroller in a digital format or else the system will need to
use an Analog to Digital convertor to convert the analog values into digital byte value.
a. Temperature sensors: The sensors use ability of materials to change their resistivity or
capacitance in response to change in their surrounding temperature. This change
causes fluctuation in current or voltage across the affected material. This change is
converted into an analog signal and measured as evidence of change in temperature.
The relation of change in current or voltage to temperature depends upon heat sensitive
material being used. The type that suits the plant requirement is one with low
resolution but wider temperature range from 0C to at least 70C. Also the sensor needs
to be low cost as many would be needed across the location with capability to provide
current levels high enough to travel substantial distance. Else signal may fade to an
erroneous value before being captured by the controller.
b. Humidity Sensor: These measure the amount of water vapor present in air. The sensor
uses a material that can respond to change in its conductivity in relation to moisture
level in air. The change in current or voltage is measured as a response to change in
water moisture level in the surrounding area of the sensor. Since the sensor must
operate without error for long duration in testing conditions, it must be made sure that
it can deal with oxidation without affecting its functionality. So it is expected to be

encased in a plastic casing exposing only the required sensor area to air for taking
measurements. Again the requirement is the signal generated by the sensor must be
amplified enough to travel distance up till it is received by the controller.
The sensors must be tested from time to time after installation to check their accuracy
as long operation times in continuous harsh environments may affect their ability to
measure the parameters. A reference sensor must always be kept in safe place to use as
reference when calibrating the installed sensors. The model and make of the sensors
used for calibration and installation must be the same.
c. Actuators: The devices are needed that can be turned on or off by the controller and
can affect other device. For the plant design, relays are best suited and they can operate
at high voltage and act like a switch. The relay can be connected between the power
supply and the device and controlled from distance to allow or disallow flow of current
to the device. The relay must be large enough to allow sufficient amounts of current to
pass through them when turned on but at the same time, capable to be switched on by
small amount of current. They are driven from microcontroller via an interface.
Interface is required to match output current levels of the controller that is in range of
few microamperes with that of the input current requirements of the relay in range of
few hundred mill amperes. Interface must also take into account the distance between
the controller physical location and placement of relays in the plant.
The controller can then decide about switching the fans on or off to get the required
conditions within the plant area. In case Microcontroller is used, the temperature may be
provided as 8 bit value that can be interpreted by the controller and decided upon. In case
a PLC is used, the sensors need to provide a single bit input like above 25 and below 25 to
decide the position of fans.
iii. Selection of microcontroller: The controller plays an important role in the effectiveness of
the whole system. The decision making is done by the controller.
a. Any delay in responding to the inputs can affect the overall system effectiveness.
This requires the controller to have speed of operation that matches the requirements
of the plant.

b. The programming of the controller should provide the ability to manipulate the sensor
inputs and drive values to output ports. The instruction set and hardware should have
capability for bit manipulation and arithmetic operations for calculations of sensor
values.
c. Microcontroller also needs to have sufficient number of I/O interfaces to connect with
all possible sensor inputs and drive the required number of actuators. The interfacing
circuit must be minimized as additional circuits increase the cost and complexity.
d. Casing of the entire controller and device interfaces needs to be packaged in an
environment resistant package. The controller should be capable of working in highly
humid environment without errors.
iv. System Design: The block level design of the typical plant is discussed here that can be
expanded to larger area if needed. The left hand side shows all sensors and right hand side
has all of actuators. Central part is the controller that processes the measurements and
generates suitable outputs.
The system shall receive the inputs from sensors as analog voltage signal continuous in
time. The inputs from sensors shall get converted into digital values using an A/D
convertor. The digital signal is such that entire range is divided into 256 levels. The output
of ADC is 1 byte in size for one sample value read from sensor. This digital value is now
read by controller and matched to pre-programmed values. The decision is taken as per the
program control flow. The result is then passed on as a digital 1 byte signal to the Digital
to analog convertor. The convertor drives the actuators as required.
v. Controller Program: the program depends upon the actual controller model being used. A
generic pseudo code for the program would be:
Temperature
Sensors
Humidity
Sensors
Analog to
Digital
Convertor
Controller
Digital to
Analog
convertor
Actuators /
Relays
Analog to
Digital
Convertor

Initialize Port 1 as input
Initialize Port 2 as ouput
Start:
Scan Port 1 for sensor values
If temperature value with 22-28 and humidity 60-80
Call Tower_Green
Call Fan_Off
Loop_start
If temperature value < 22 or humidity < 50
Call Tower_Orange
Call Fan_Inflow
Loop_start
If temperature value > 30 or humidity > 80
Call Tower_Orange
Call Fan_Outflow
Loop_start
If temperature value < 15 or humidity < 25
Call Tower_Red
Call Fan_Inflow
Loop_start
If temperature value > 40 or humidity > 85
Call Tower_Red
Call Fan_Outflow
Loop_start

vi. A comparative evaluation of the developed systems: Systems based on
Microcontroller are more adaptable to change in setup if need be. The optimum
temperature and humidity conditions vary based on variety of tomato and may be
entirely different for a different crop type. Using microcontroller with input feature to
set required temperatures and humidity levels can help in case of a new crop or new
variety. Sensor calibration is also possible in case microprocessors are used. All of
this flexibility is not possible in case of PLCs.
Next is hardware upgrade is easier with Microprocessor if a new sensor has to be
added to the existing system or a new actuator is to be added. PLC is hardwired that
makes it hard to modify or upgrade to accommodate a new input/output device.
Overall microprocessor is more costly at initial stage but flexibility of the system pays
off in the long run.
Conclusion
Sensors need to be chosen for wider range of measurement than for higher
resolution. Temperature sensor with range of 0⁰C to 100⁰C is preferred in resolution
of 1⁰C. Speed of communication is not a concern but operating time should be in
weeks without fail. Sensors must be checked for calibration from time to time.
A microprocessor based system is preferred for implementation for the plant. The
number of sensors and actuators will depend upon the area to be supervised and may need
external interface to multiplex sensor inputs to the controller. Similarly de-multiplexer might
be needed as an external interface to connect actuators for devices.