An alert system using arduino and nodemcu
AN ALERT SYSTEM USING ARDUINO AND NODEMCU
SVTH:Đỗ Chí Bằng
GVHD: TS Tạ Quang Hùng
Tó m tắt - Trong thời gian gần đây, thuật ngữ “Hệ thống nhúng” đã trở nên phổ biến hơn đối với
người dân, đặc biệt là sinh viên ngành Cô ng nghệ thông tin (CNTT). Điều này một phần là do sự ra
đời của bộ vi điều khiển đơn bo mạch Arduino và bộ vi điều khiển để xâ y dựng cá c thiết bị kỹ thuật số.
Mặc dù đã có những thiết kế dành cho cá c thiết bị bảo mật có thể truy cập được trên internet, nhưng
rất í t trong số chúng được kết hợp với Internet of Things - một trong những chủ đề nó ng hổi liên quan
đến CNTT. Bài bá o này nhằm mục đích hướng dẫn những người có một số kiến thức nền tảng về
CNTT để xâ y dựng một cảm biến phá t hiện người trước khi gửi thông tin đến điện thoại, cảnh bá o cho
chủ sở hữu của cảm biến. Hơn nữa, bài bá o này sẽ giải thí ch một số chi tiết chí nh về việc chế tạo
thiết bị và sẽ được dùng làm tài liệu tham khảo cho cá c dự án trong tương lai trong việc tạo ra cá c
thiết bị IoT.
Abstract - In recent times, the term “Embedded System” has become more popular to the
people especially Information Technology (IT) students. This was partly due to the introduction of
Arduino single-board microcontrollers and microcontroller kits for building digital devices. While there
has been designs for security devices that are accessible on the internet, few of them are combined
with Internet of Things – one of the hot topics regarding to IT. This paper aims to guide people with a
some IT background knowledge to build a sensor that detects people before sending the information
to a phone, alerting the owner of the sensor. Moreover, this paper will explain some key details about
the making of the device, and would be serve as a reference for future projects in creating IoT
devices.
Key words: Arduino, Embedded System, IoT.
I. Introduction
The field of security systems is also in development. Security devices are increasingly
being introduced to the market and it can be difficult to choose among different types of
devices with different functionality. In spite of the many differences between devices, it is
important to note that most of the security systems works on the same principle and have
similar framework. Noticeably, sensors play a crucial role in the field of security system.
There are many types of sensors namely ultrasonic sensor, photoelectric sensor, microwave
sensor, Passive Infrared Sensor, noise detector etc. These sensors helps to detect a certain
object and report the information back to the controller for further processing. It can be
applied to a lot of situation, notably in detecting people.
Personally, the idea of making an alerting device came to me as I was working on my
computer while wearing a headphone, unaware of the surroundings, only to realized there
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were guests visiting my parents downstairs. The thought of the question “what if it wasn’t a
guest, but a burglar?” came to mind and I started to wonder if it is possible to create a ‘do-it-
yourself’ (DIY) device that helps me to detect “uninvited guests” – intruders. However, a
wired system with strings and contraptions are only applicable in the movies but not in
reality. Wired contraptions and even wired electronic devices are out of date and its
applications are limited. Thus, wireless security devices are preferred. They are user-friendly,
simple and fast. With a proper battery backup and internet they will still operate wonderfully
even during power outages. For that reason, this paper will provide a guide on making a
device that can sense people, alerting the owner by sending notifications to a smartphone.
II. Component and supplies
A. Hardware
1. Arduino Uno
According to Felgo on 2020, Arduino is one of the most recommended single-board
microcontroller, especially for Embedded Computing. Being one of the most commonly used
open-source microcontroller board, Arduino Uno is considered to be the most optimal
solution for personal projects. It is the open-source microcontroller board based on the
Microchip ATmega382P microcontroller, equipped with 14 digital input/output (I/O) pins and
six of which is capable of PWM output. Another 6 programmable analog I/O pins are also
equipped.
The main reason that Arduino products, namely Arduino UNO is the optimal solution
for this project is the simplicity of its set up. The board is programmable with the Arduino
IDE (short for Integrated Development Environment), by connecting the board to the
computer using a Type B USB cable. This cable can provide power to the board but an
external 9-volt battery can also be used as a power source for the Arduino UNO (voltages
between 7 and 20 volts are acceptable). Another reason for it’s popularity is due to the large
amount of tutorials and guides is available online for further understanding of the board.
Since Arduino is open-source, the library available on the internet is huge. People can help
each other create and develop new resources for the software improvement.
Figure 1: Arduino UNO
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2. NodeMCU
In a few guides and tutorials in making a similar security device, Bolt IoT Bolt Wifi
Module is suggested for IoT integration (Hrushikesh S Bharadwaj & Pawan Kumar, 2020) .
However, as a personal experience, I discovered that it is not only expensive, but also not
fully available to some countries specifically Vietnam. Thus, to have a cheaper and better
solution, this paper will suggest NodeMCU for this project. It is easy to acquire, inexpensive
and a larger range of customization.
However, regarding cyber security in NodeMCU, it is dependent on the programmer to
provide the necessary means to protect the device from hackers to connect and take control of
the device. Since this project is served as a personal project, cyber security will not be the
main focus of this paper.
Figure 2: ESP8266 NodeMCU
3. Ultrasonic Sensor HC-SR04
Figure 3: Ultrasonic Sensor HC-SR04
In this paper, we would suggest the Ultrasonic Sensor HC-SR04 because it is common
on the market, with reasonable price and good functionality. This Distance Sensor can report
the range of object up to 4 meters away which is enough for our alert system (Sunfounder,
2019). The sensor also use low power so it is suitable in case of using battery power supplies
for the device (Lastminuteengineers, 2021). Some notable specifications are the Operating
Voltage, Operating Current, Operating Frequency, max Range, min Range, Ranging
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Accuracy, Measuring Angle, Trigger Input Signal and Dimension are provided in the
following table:
Operating Voltage
Operating Current
Operating Frequency
Max Range
DC 5V
15mA
40KHz
4m
Min Range
2cm
Ranging Accuracy
Measuring Angle
Trigger Input Signal
Dimension
3mm
15 degree
10µS TTL pulse
45 x 20 x 15mm
Table 1: Ultrasonic Sensor HC-SR04 specification
4. Buzzer (Optional)
The buzzer (or beeper) is a commonly found component in a lot of devices, and even in
some toys. This is an audio signaling device, which can help sending out audio signals to alert
people on detection (Sunfounder, 2016). This Buzzer can be coded to send out tunes with
different tones by limiting the power current of the buzzer. It is optional depending on the
maker’s preference.
Figure 4: Buzzer
5. Jumper wires (generic)
Jumper wires (also known as Jump wire, Jumper, DuPont wire or cable) is an electrical
wire that has a connector or pin at each end or tinned. This is used to wire the component of a
breadboard, for example to easily interconnect the pins of the Arduino UNO with other
components like the buzzer. It is very cheap and easy to find, but as a tip for beginners, there
are 3 types of jumper wires that should be known: the Male to Male, Female to Female and
the Male to Female jumper wires. The male end is the end of a jumper wire that has a solid
pin tip for plugging into the things such as the breadboard while the female ends do not and
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are used to plug things into. Depending on the need of what kind of pins the components
have, some Male to Male wires are necessary and some Male to Female wires are required.
Figure 5: Jumper wires
6. Breadboard
When working with Arduino, welding would be extremely troublesome particularly
when it is uncertain if a connection is correct or not. For beginners and experimentalists, a
breadboard would solve most issues in creating a circuit and building the device. It is
absolutely user-friendly and straightforward. The following yellow lines indicates the way the
circuit is connected between the holes of the breadboard.
Figure 6: Breadboard circuit
7. Button (optional)
A push switch or a button is an optional choice in this project because normally it is not
required to activate the alarm system manually. In some cases that you wish to turn the device
into a doorbell that has the same alerting function, a button would not be irrelevant.
Figure 7: Push switch
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B. Software
1. Arduino IDE
Arduino IDE is an application that is noticeably based on C and C++. Not only it is used
to write and program Arduino boards, it can also be used for other development boards with
the help of third-party cores. It is a free software that anyone can download effortlessly on its
mentioned in a Arduino Introductory book by Alan G. Smith, you are now able to write codes
and compile them, ready to upload to your connected Arduino board using just a single click.
Figure 8: Arduino IDE
2. Twilio SMS Messaging API
Twilio is an American cloud communications platform as a service (CPaaS) company.
They provides software developers web service APIs that allows users to make and receive
phone calls, send and receive Short Message Services (SMS) and many more communication
functions. It is used in this project due to its convenience, programmable features and most
importantly, its trial services. For experimental purposes, we will use the free trial of their
products, however, a subscription fee would be required for satisfied users who choose to
extend their usage on the device or further IoT related projects.
III. Implementation
A.
1.
Software
Arduino IDE - Esp8266 support
NodeMCU is a firmware that runs on the ESP8266 Wifi SoC and is not manufactured
by Arduino, so it is needed to install an extension to Arduino IDE for the software to be able
to upload the code to the NodeMCU.
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2. CH340 or CP2102 driver
In some cases, the UART device cannot recognize your NodeMCU. This maybe due to
the lack of correct driver in your computer. Your purchased ESP8266 NodeMCU may has a
CP2102 chip or a CH340 chip. This can be solved by updating the driver for the chip.
3. Twilio account setup
Setting up a Twilio number is an important part of the device. Noticeably, there are
three key items that is needed for NodeMCU:
- Your trial number is the number you will receive the SMS from.
- Your account SID which can be copied and should be kept to yourself.
- Your Auth token which is extremely important and must be kept a secret.
B. Schematics
1. Precaution
In some guides, it is said to connect the Arduino Tx pin to the ESP8266 NodeMCU Rx
pin. A caution regarding this method is that it possesses the risk of damaging the ESP8266
NodeMCU pin due to the pin working on 3.3V (Robotica DIY, 2020). This problem should
be solved by using a voltage divider or reducing the Arduino’s power supply voltage.
Figure 9: Voltage divider (Fritzing)
Another notable precaution is that the wiring process should be done with great care. A
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clean and clear board is always approved. Moreover, in order to avoid short circuit, it is
supported to always visually check the circuit and to measure the voltage between two ends.
2. Wiring
For experimental purposes and for simplification of the process, we will connect the D1
and D2 GPIO pins to the Arduino UNO. Since SoftwareSerial Library will be used for Serial
Communication between Arduino UNO and the NodeMCU, the mentioned pins specifications
will also operate smoothly. Therefore, the following circuit design will be used.
Figure 10: Demonstration of the circuit
Figure 11: Alert system schematic
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C. Mechanism
1. Arduino UNO
After defining the pins and establish the Serial Communication between Arduino UNO
and NodeMCU by using SoftwareSerial library, the sensor will start scanning for any
response changes of its max travelling distance. These values may varies but once it reached
under 30, meaning there is an obstacle blocking the sensor, making the buzzer to be activated
and the alert system activated. Controled by the Arduino UNO, a byte type data of “115” –
which in ASCII codes imply the character “s”, to the NodeMCU.
Figure 12: Ultrasonic Sensor triggering
Figure 13: Arduino UNO output
2. NodeMCU
In the beginning, the NodeMCU will initiate the pins as well as the Serial
Communication with the Arduino UNO, before declaring the key variables: the ssid of the
wifi, the password of the wifi, the Twilio account sid, the Twilio’s authentication token, the
Twilio number, the user’s phone number and the message body.
On the declaration step, a Fingerprint array is provided by Twilio, although it may be
changed in the future, it can be updated on Twilio’s document page. By connecting to Twilio
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API service using the guide from their official page (Twilio, 2020), the NodeMCU can now
send request to Twilio using the “sendSMS()” function.
Figure 14: NodeMCU output
On setup function, NodeMCU will run a check whether it can connect to the Wifi using
the declared SSID and password, while checking for a connection to Twilio API service with
the declared SID and token.
After the process, the NodeMCU is now ready to work and receive data from Arduino.
If a 115 byte data is received from Arduino UNO, the program will recognize it as a trigger to
send a SMS to the registered phone, alerting the owner (TigerFarmPress, 2020).
Figure 15: SMS received
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IV. Conclusion
Obviously the paper is guided towards making an alert system with IoT integrated.
However, it shows the possibility of multiple different applications for sensors and IoT alike.
With some tweaking, this device could be programmed to become a monitoring program or a
sensor of a Wifi controlled car. In summary, with the help of Arduino and open-source
resources, Embedded System and IoT related projects (e.g., a security system) are now more
accessible for everyone.
REFERENCES
[1] Alan G. Smith, (2011) "Introduction to Arduino" (PDF). princeton.edu. Archived
from the original (PDF) on 3 April 2018. Retrieved 4 February 2018.
[2] Felgo, 2020. "6 Best Microcontrollers: Hardware for Embedded Computing"
[3] Hrushikesh S Bharadwaj, (2020) "Intruder ALERT!!!"
[4] Lastminuteengineers.com, "How HC-SR04 Ultrasonic Sensor Works & Interface It
[5] Magesh Jayakumar, Quick Start to Nodemcu (ESP8266) on Arduino IDE.
[6] Pawan Kumar, (2020) "Intruder Alert System"
[7] Robotica DIY, (2020) "Send Data From Arduino to NodeMCU and NodeMCU to
[8] Sunfounder, 2016 "Buzzer modules".
[9] Sunfounder, 2019 "Ultrasonic Module".
[10]TigerFarmPress, "Send an SMS Using an ESP8266"
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