An electronic sensor Figure 5 that measures the infrared light radiations from the object in the field. It was mostly used in the PIR-based motion detector. This sensor is commonly used in the security alarms and automated lighting applications. The PIR Sensor allows you to realize motion, and this sensor is used to detect the human motion and whether the person is moved out of range. For this reason, the main appliances and equipment are LED in homes or for businesses. They are mostly referred to as “Passive infrared”, “pyroelectric”, or the “IR motion” sensors. The PIR Sensor is made up of pyroelectric sensor (which you can see in ( Figure 2 . PIR Sensor) it is a round metal with a rectangular crystal in the center, which is used to detect the level of infrared radiation. Everything in it emits the low level of radiation, and the warmer it is, and it more radiation is emitted. And this sensor is the motion detector and it was divided into the two parts. The reason for this is we have to finalize the speed change and not the average IR level. In these two halves are removed so it easily cancels each other. If one halves is more or less than the IR radiation then the other output will swing higher or lower [4] .

HC-SR501 Specifications ( Table 1 & Figure 6 )

Adjusting the HC-SR501

On the back of the board, you will and two potentiometers and a jumper which you can use to adjust several parameters:

Sensitivity (range) adjustment

The HC-SR501 has a maximum sensing distance (detection range) of 7 meters. You can adjust the sensing distance by rotating the sensitivity potentiometer CW or CCW (see picture above). Rotating the potentiometer clockwise increases the sensing distance to a maximum of 7 meters. Rotating it counterclockwise decreases the sensing distance to a minimum of 3 meters.

Time-delay adjustment (Tx)

This potentiometer can be used to adjust the time that the output stays high after motion is detected. At a minimum, the delay is 3 seconds and at a maximum, it is 300 seconds or 5 minutes. Turn the potentiometer clockwise to increase the delay and counterclockwise to decrease the delay.

Trigger selection jumper

The (yellow) jumper can be used to select one of the two trigger modes. It can be set to either L (single trigger) or H (repeating trigger):

Single trigger—The output will turn HIGH as soon as motion is detected. It will stay HIGH for the time set by the potentiometer. Any movement during this period is not processed and does not restart the timer.

Repeating trigger—Every time motion is detected, the delay timer is restarted.

Connecting HC-SR501 PIR motion sensor to Arduino UNO as per Table 2 .

The Ultrasonic transmitter sends out an ultrasonic wave, which travels through the air and is reflected back toward the sensor when it encounters any material. The Ultrasonic receiver module detects this reflected wave, as illustrated in the diagram below Figure 7 [5] .

HC-SR04 Ultrasonic Sensor-Working ( Table 3 & Figure 8 )

The HC-SR04 Ultrasonic (US) sensor is a 4-pin module, whose pin names are Vcc, Trigger, Echo and Ground respectively. This sensor is a very popular sensor used in many applications where measuring distance or sensing objects are required. The module has two eyes like projects in the front which form the Ultrasonic transmitter and Receiver. The sensor works with the simple high school formula that

Distance = Speed × Time

Now, to calculate the distance using the above formulae, we should know the Speed and time. Since we are using the Ultrasonic wave we know the universal speed of US wave at room conditions which is 330 m/s. The circuitry built on the module will calculate the time taken for the US wave to come back and turn on the echo pin high for that same particular amount of time, this way we can also know the time taken. Now simply calculate the distance using a microcontroller or microprocessor

Operating voltage: +5 V

Theoretical Measuring Distance: 2 cm to 450 cm

Practical Measuring Distance: 2 cm to 80 cm

Accuracy: 3 mm

Measuring angle covered: <15˚

Operating Current: <15 mA

Operating Frequency: 40 Hz

How to use the HC-SR04 Ultrasonic Sensor ( Figure 9 )

HC-SR04 distance sensor is commonly used with both microcontroller and microprocessor platforms like Arduino, ARM, PIC, Raspberry Pie etc. The following guide is universal since it has to be followed irrespective of the type of computational device used.

Power the Sensor using a regulated +5 V through the Vcc and Ground pins of the sensor. The current consumed by the sensor is less than 15 mA and hence can be directly powered by the onboard 5 V pins (If available). The Trigger and the Echo pins are both I/O pins and hence they can be connected to I/O pins of the microcontroller. To start the measurement, the trigger pin has to be made high for 10uS and then turned off. This action will trigger an ultrasonic wave at frequency of 40 Hz from the transmitter and the receiver will wait for the wave to return. Once the wave is returned after it gets reflected by any object the Echo pin goes high for a particular amount of time which will be equal to the time taken for the wave to return back to the sensor [6] .

The amount of time during which the Echo pin stays high is measured by the MCU/MPU as it gives the information about the time taken for the wave to return back to the Sensor. Using this information, the distance is measured as explained in the above heading.

For example, if the item is 20 cm away from the sensor and the sound speed is 340 m/s (0.034 cm/s), the sound wave must travel for approximately 588 microseconds as per Figure 10 . The number you’ll obtain from the Echo pin, though, will be double that because the sound wave must travel forward and backward. To calculate the distance in cm, multiply the received travel time value from the echo pin by 0.034 and divide by two.

Application:

- Used to avoid and detect obstacles with robots like biped robot, obstacle avoider robot, path finding robot etc.

- Used to measure the distance within a wide range of 2 cm to 400 cm

- Can be used to map the objects surrounding the sensor by rotating it

- Depth of certain places like wells, pits etc.

- Can be measured since the waves can penetrate through water

The Arduino Nano is a small microcontroller, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x). It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one [7] .

Safety and cost-effectiveness

More than 500 charge and discharge cycles are possible with this battery cell. This makes it very cost-effective, and it has a life expectancy that is comparable to that of the device in which it is utilized.

Long cycle life

Provide a lengthy storage life with little constraints. It provides trouble-free charging after extended storage, allowing it to be used in a variety of applications

Applications

Electric toy, power tool, electric back-up.

This is FS1000A 433 mHz Tx RF Radio Module. This RF module comprises an RF Transmitter Figure 13 and an RF Receiver Figure 14 . The transmitter/receiver (Tx/Rx) pair operates at a frequency of 433 MHz. An RF transmitter receives serial data and transmits it wirelessly through RF through its antenna connected at pin4.

The transmission occurs at the rate of 1 Kbps - 10 Kbps. The transmitted data is received by an RF receiver operating at the same frequency as that of the transmitter. This low-cost RF transmitter can be used to transmit signals up to 100 meters (the antenna design, working environment, and supply voltage will seriously impact the effective distance). It’s good for a short distance, battery power device development. 433 MHz is the operating frequency for transmitter and receiver pair.

Features:

1) Wide input supply (2.5 V to 12 V)

2) Easy to integrate (V+, GND, and Data)

3) The device in deep sleep mode when Data pin is grounded

4) Very small dimension.

Figure 15 & Figure 16 show the block diagram and flow chart of the system.

Utilized the HC-SR501 human body infrared sensor module for this project. Two triggering techniques are available for the HC-SR501 human body infrared sensor module. The first is non-repeatable triggering, which means that after the sensor has output a high level and the wait time has passed, the output will automatically change from high to low. Simply put, it will produce a high level when it detects human movement, but it will stop sensing after the timer on its delay adjustment button has expired, even if a person moves in front of it. The HC-SR501 features a 0.2-second lockout period during which it will not work. After the lockout period is complete, it will If a human body is moving within the sensor’s sensing range during the delay period, the sensor’s output will remain high until the person leaves. Reduce the high level to a low one (the sensing module will automatically extend a delay time period after detecting every activity of the human body, and take the time of the last activity as the starting point of the delay time). Simply said, the HC-SR501 will always produce a high level if you keep moving in front of the human infrared sensor module continue to sense. A repeating trigger mode is also available.

This is the 12 LED ring, a small chainable 85 mm outer diameter board equipped with 5050 WS2812 RGB LEDs. The WS2812s are each addressable. The driver chip is located inside the LED. Each Stick has ~18 mA constant current drive so the color will be very consistent even if the voltage varies, and requires 5 V. Every ring is equipped with a single data line with a very timing-specific protocol requiring a real-time microcontroller with an 8 MHz or faster processor such as an AVR, Arduino, PIC, embed, etc. There are solder pads on the back for connecting wires or breadboard pins and two mounting holes for securing this board to many different surfaces.

Specifications

IC Chip: WS2812B

Supply Voltage: 5 (V)

Color: RGB

No of Light: 12

Features

The control circuit and the LED share the only power source. The control circuit and RGB chip are integrated into a package of 5050 components, forming a complete control of pixel points. Built-in signal reshaping circuit, after wave reshaping to the next driver, ensures wave-form distortion does not accumulate. Built-in electric reset circuit and power lost reset circuit.

Each pixel of the three primary colors can achieve 256 brightness levels, or 16 M colors full-color display, and scan frequency not less than 400 Hz/s Cascading port transmission signal by a single line [8] .

For any two points, the distance is more than 5 m transmission signal without any increase circuit.

When the refresh rate is 30 fps (frames per second), the cascade number is not less than 1024 points.

Send data at speeds of 800 Kbps.

The color of the light was highly consistent

Full-color module, Full-color soft lights a lamp strip.

LED decorative lighting, Indoor/outdoor LED video irregular screen.

Package includes

1*12 Bit ws2812 5050 RGB LED Small Ring with Fashion Light & Buzzer as shown in Figure 17 .

The ESP8266 WiFi Module is a self-contained SOC with integrated TCP/IP protocol stack that can give any microcontroller access to your WiFi network. The ESP8266 is capable of either hosting an application or offloading all Wi-Fi networking functions from another application processor.

The module has a wireless WiFi transceiver operating in an unlicensed frequency range of 2400 - 2484 MHz in the IEEE 802.11 b/g/n standard, with support for TCP/IP communication protocol stack and WiFi security including WAP3, Figure 20 .

Purpose: using the Ultrasonic Sensor to sense distance and ESP8266-01 to send the data over WiFi.

For transmission over WiFi, ESP8266-01 is used. It is configured by the AT Commands. The ESP connects with the Access point and becomes Web Server, when the specified IP of the ESP module is browsed ( Figure 21 ).

Blynk ( Figure 22 ) is a new platform that allows you to quickly build interfaces for controlling and monitoring your hardware projects from your iOS and Android device. After downloading the Blynk app, you can create a project dashboard and arrange buttons, sliders, graphs, and other widgets onto the screen.

Step 1: Setting up the Blynk app ( Figure 23 ):

Step 2: Select name and Board then Press Create as per Figure 24 .

Step 3: This is a very important step. Hear you got your AUTH TOKEN it sends to your email address. Press OK

Step 4: Now go to Widget Box and select Notification as per Figure 25 .

Step 5: Will look like that Figure 26 .

After all the connections are done and the code is uploaded, the Red LED on Pin D0 should light up whenever a human comes within the detectable range in front of the PIR Sensor. Also, User is notified through Blynk app.

The main objective of this project is to keep individuals at a safe distance from one another. PIR sensor is used in this proposed work we protect people as much as possible from the effects of this epidemic virus and reduce people’s exposure to it as much as possible by alerting people with a sound alarm (beep) When PIR sensor detects the motion, the ultrasonic sensor used to check the pulses to compute the distance in between the obstacle or a person. This is terminated by converting the pulse back to the distance it takes. After measuring the distance, the information is coded and sent, the LED turns on if the distance is less than six feet and turns off if it is more than six feet [9] .

1) It is possible to add a developed camera to the sensor used in the project and make special programming to simulate the camera with the sensor so as to improve the principle of the sensor’s work so that it becomes able to distinguish the human element compared to anything inanimate by seeing it with the camera.

2) The device can be connected to the Internet by placing an internet chip inside the device and linking it to the databases of the Ministry of Health and the Civil Status Department so that when the device sees a person through the camera, it can send it to the databases of civil status records and match the image that the device takes with the images in the civil ID and know the name of the person And then it is sent to the databases of the Ministry of Health and to know whether the person is infected or not.