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DOI: 10.14738/aivp.92.9766
Publication Date: 25th March, 2021
URL: http://dx.doi.org/10.14738/aivp.92.9766
Digital Monitoring Circuit for Controlling
A Limit Based Parameter Value
1
Lianly Rompis
1
Electrical Engineering Study Program, Faculty of Engineering
Universitas Katolik De La Salle Manado, Indonesia
lrompis@unikadelasalle.ac.id
ABSTRACT
Industrial Revolution 4.0 relates to many digital devices, machines or applications that integrates with
internet and needs to be controlled on one or two of its parameter values regarding the importance
of output in order to function correctly. Those parameter values have standard limitation and essential
automation procedures should be taken for keeping the good operation of devices, machines or
system. Controlling a limit based parameter is difficult if done manually and needs full concentration.
Digital monitoring circuit would be very helpful for doing that controlling with the support of digital
technology development nowadays. The usage of monitoring circuit currently applied in many fields
especially for monitoring the condition of a patient in a hospital bed. Regarding health management
and digitalization, digital monitoring circuit becomes very important and needs continued
improvement.
Based on the problem above, this paper is conducted a research to design a digital monitoring circuit
for the purpose of controlling a limit based parameter value for patient medication. The research
methodology contains literature study, analysis and logic simulation. The outcome derives a reliable
digital logic circuit that could be implemented into a real digital circuit or Integrated Circuit (IC)
components to help people controlling the condition of a patient based on limit parameter value and
support medical industries to improve their devices, machines or system performance to work more
accurately and give out best medical services.
Keywords: Logic Circuit; Digital Electronics; Parameter Control; Medical Tool; Medication.
1 INTRODUCTION
Currently Indonesia is facing the era of Industrial Revolution 4.0 or we called it Revolusi Industri 4.0.
This era applies automation concept for machines that do not required man power in their
applications. Today industrial evolution continues the previous Industrial Revolution 3.0 that becomes
startup for a digital revolution by combining innovations and creativities in Electronics and
Information Technology field. Automation and Digital are parts of the essential concepts in Industrial
Revolution and are putted as an important role for controlling and organizing the works of a device or
a machine or an application to meet the operational tasks. Automation sometimes deals with one or
few parameters which are needed to be measured from their limitation. These kinds of value
mainly have a limit value that considered important to be set up for alarm and better performance.
Not every device or machine or application has limit based parameter value and should be controlled,
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Rompis, L. (2021). Digital Monitoring Circuit for Controlling A Limit Based Parameter Value. European Journal of Applied
Sciences, 9(2). 97-106.
URL: http://dx.doi.org/10.14738/aivp.92.9766
but surely there are some of them that truly need a control handling to notice the limit and get the
right procedure for improvement.
The examples of device or machine or system that have a limit based parameter value e.g. patient
monitor, chemical substance production, data traffic, voltage or current measure, and etc. Based on
the importance reason of automation and supported by digital technology improvement and
development, in this research author learned how to design a digital monitoring circuit for controlling
a limit based parameter. Author designed and derived a principle common logic circuit that could be
applied with any sensor although it might need an analog-digital converter for the input.
This research came from the problem discussed in University of Michigan. It talks about how to design
a sequential circuit for monitoring the condition of a patient in a hospital bed [5]. This Problem then
was brought into digital system classroom and determined the solution by author so students can learn
more about the course, know exactly how the combinational and sequential circuits work and how
they can be implemented or integrated as one to build a logic circuit.
Learning from the basic concept of digital system and doing proper analysis, author managed to
derive a digital logic circuit for that patient monitor problem and reflected a digital monitoring circuit
that logically can be designed and applied commonly and putted into fabrication by electronics factory
or electronics industry.
2 Research Methodology
For this research, author conducted three procedures: literature study, analysis and logic
simulation. The output concludes a design of digital monitoring circuit that can be used for controlling a
limit based parameter value of a Patient Monitor. This logical design can be applied in the form of
algorithm using microcontroller or other computer devices.
3 Literature Study
The digital monitoring circuit was designed using combinational and sequential circuits i.e. logic gates and
flip-flops which are very familiar to students, scientists and circuit designers. It is easy to understand how
the logics work. The future works of this research bring out the implementation of digital circuit into
electronic component or digital IC or software algorithm. The future research can be done by electronics
industry or university.
As been explained previously, the idea of this research came from a digital system problem discussed in
course. The problem stated about designing a sequential circuit patient monitor, a circuit for monitoring
the condition of a patient in a hospital bed as being described and explained in figure 1 [5].
This is an application problem that catched author attention to bring and solve it into classroom learning
at the end of the digital system course. With this application and the solution given, students can
understand the theory of combinational and sequential circuits more easily and improve their point of
views.
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Figure 1. Problem or Question that Builds the Idea
From this patient monitor problem, author tried to learn and learn and did research to derive a solution,
a digital monitoring circuit for controlling a limit based parameter value. So the digital logic circuit does
not only can be used for patient monitor, but it also can be used for other
applications that need controlling on their parameter value.
The research studied about combinational and sequential circuits that were related to logic components
such as logic gates and flip-flops.
3.1 Logic Gate
Logic gate is the fundamental logic component that builds digital technology. The basic concept
started from binary number that only has logic 0 and logic 1.
These simple logic creates the logical thinking for computers or digital devices so they can think and
work structurely with the help of program instructions. There are 8 (eight) logic gate components:
NOT gate, BUFFER gate, AND gate, NAND gate, OR gate, NOR gate, XOR gate and XNOR
gate. These gates works logically according to their logic truth table [1-4].
3.2 Flip-Flop
Flip-Flop is a basic component of combinational logic circuit and sequential logic circuit, mostly used to
build a counter or register circuit. The design for flip-flop comes from logic gate circuits. D Flip-Flop is one
of the main flip-flops that normally functions as a latch. It has an input and two outputs [1-4].
3.3 Register
Register is a type of sequential circuit mainly for storing information. There are three common types of
register, right shift register, left shift register and parallel register. Shift register is built from a group of
flip-flops, usually D-FF, connected in a loop so that the output from one flip-flop becomes the input of
the next flip-flop, and so on [3,9]. The input is serial and shifted from the left side to the
right side or from the right side to the left side. A right shift register is shown in figure 8. All flip-flop
components are driven by a common clock, and they are set or reset simultaneously. Parallel register
has similar logical task except it is in parallel connection.
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Rompis, L. (2021). Digital Monitoring Circuit for Controlling A Limit Based Parameter Value. European Journal of Applied
Sciences, 9(2). 97-106.
URL: http://dx.doi.org/10.14738/aivp.92.9766
3.4 Counter
Counter is another type of sequential circuit mainly for counting binary data or information. There are
two common types of counter: synchronous and asynchronous counter. Synchronous counter would be
selected if we need a common clock thet triggers the flip-flop output
simultaneously, while asynchronous counter would fit best if in design we need asynchronous source of
clock for each flip-flops.
Asynchronous Counter is a sequential logic circuit function which all the inputs of flip-flop components
are connected together to logic 1 (standard high dc voltage). The first clock is connected to a clock
source, while the other clocks need to be connected to output Q from previous flip-flop. The number of
bit depends on number of flip-flop being used. For example, to have a design of output values in 4-bit
length we use 4 (four) flip-flops [6-8,10].
4 Analysis and Observation
4.1 Analysis
Based on the previous background, author conducted analysis to derive the block diagram of digital
monitoring circuit. According to the standard design procedure for logic circuit, digital monitoring circuit
have three parts: input, process and output [3].
Both input and output are digital information, so whatever comes to input should be in binary value and
the output also will be in binary and if necessary can be converted into analog value.
The input which is expected to go inside the digital monitoring circuit is a parameter value. If we use
analog sensor, we need to change the analog value into digital value using Analog to Digital Converter
(ADC). In process, this binary information from input will be stored in register
and stays there until a specific timing and will be retrieved for output processing. The length of input
depends on the sensor specification and digital monitoring circuit standard fabrication, for example 8-bit
or 16-bit. Each string of bits is relate to a specific value. The logical block diagram is derived in figure 2.
Figure 2. Logical Block Diagram of Monitoring Circuit
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4.1.1 Register Module
For analysis, author used 3-bit binary information as input, named ABC and a parallel register module as
described in figure 3.
Figure 3. Parallel Register Circuit from D-FFs
When the binary inputs are detected from a sensor, they will reach the register input and stored in it until
the clock being triggered for retrieving the data output and displaying into monitor.
4.1.2 Timing Module
The next module is the timing circuit. This circuit sets the time for controlling
a limit based parameter value. This circuit will trigger the register’s clock then drive all the inputs
into outputs. It could be built from counter circuit (JK-FFs) or used IC that accomodate the source
of clock for timing.
For analysis, author used a 3-bit asynchronous counter circuit as given in figure 4. This counter counts up
from 0 to 7 as explained in table 1.
Figure 4. a 3-bit Asynchronous Counter
Suppose we need a system to automatically check the machine’s limit based parameter value every 2
minutes. Timing circuit should be designed appropriately to meet the controlling time requirement
by given a logic signal to trigger register’s clock every 2 minutes. If more time is needed,
modify the frequency or program instructions.