An Introduction to Arduino Compatible Sensors

Author: Darhan Saami

The Arduino is an incredible product that has been celebrated by numerous tech and electronics enthusiasts worldwide. However, there is only so much an Arduino can do on it’s own. This is where countless Arduino-compatible add-ons and modules come into play.
In this blog, we shall dive deep into the five most popular Arduino-compatible sensors that you might be interested in. The blog will discuss the functionalities, explain the setup and working process, and give example-projects for each sensor. As for the programming part, do not worry as customizable documentation of codes and Arduino sketches are available on the internet. All these sensors are purchasable from almost all reliable e-commerce platforms and are readily compatible with the Arduino UNO.

ePro Labs TTP223 Capacitive Touch Sensor Module for Arduino

There was a time when we tech lovers were freaked out by the touchscreen features on the iPhone. To make your project touch-sensitive, you can use a touch sensor with your Arduino. A touch sensor responds to touches of all sensitivity levels by activating itself and performing an action. What is even cooler is that the touch sensor can sense different touch nodes, e.g., a single tap, long press, swipe left or right, etc. A touch sensor can be handy in trivial projects, such as mouse traps or dimmer switches, to more extensive projects, like security alarms. The ePro Labs TTP223 Capacitive Touch Sensor is an excellent choice that is compatible with the Arduino UNO. This particular sensor can replace the traditional buttons on a vast range of consumer products and household switches.

How exactly does the touch sensor work? The Arduino detects the changes in the logic state of the sensor when we touch it. Of course, the Arduino UNO’s consequent reaction to changes in the logic state of the sensor has to be programmed through an Arduino sketch.

The Touch Dimmer Switch Circuit is an enjoyable and simple project to start learning this sensor. For this project, you will need the TTP233 Touch Sensor, Arduino UNO, a small bulb, a 1-kiloohm resistor, a breadboard, a 2N2222 NPN transistor, jumper wires, and a power supply. The sensor comes with five pins: VCC, GND, SIG, and 5V. All these pins are connected with the Arduino UNO and power supply. Once the circuit connection is established, and the Arduino sketch is uploaded, you can dim or brighten the bulb’s lights at the ease of your touch. What a cool way to make your desk lamp, right?

YL-69 Soil Moisture Sensor

A soil moisture sensor (also known as a hygrometer) is designed to detect the humidity of any soil. It is generally used in greenhouses or backyard farms to automate the watering system. You can use it to test soil quality or monitor any gardening project you may have in mind. The YL-69 soil moisture sensor is a brilliant choice and easy to set up for any beginner.

The two soil sensors essentially comprise two pieces: an electric board and a probe with two pads. These sensors come with in-built potentiometers to sense and adjust the digital output (D0), the digital output LED, and the power LED.

So how does this sensor work? The sensor varies the voltage it outputs with changes in the moisture level in the soil. The output voltage falls in wetter soil and rises in drier soil. Again, depending on the water content, the digital signal outputs either a LOW or HIGH. The threshold for these digital signals can easily be adjusted using a potentiometer on the sensor.

To get comfortable with this sensor, the project we suggest you consider is to read and display the analog output values with the help of the Arduino UNO on a monitor. For this project, you will need one YL-69 moisture sensor, the Arduino UNO, one breadboard, two 220-ohm resistors, red and green LEDs, and few jumper wires. Once you have all the necessary parts, start wiring the sensor to your Arduino UNO using the jumper wires. The A0 on the sensors connects with the analog pins on the Arduino UNO, D0 goes to the digital pins, GND goes to the GND, and VCC connects with the 5V port Arduino. Once done, upload your sketch onto the board. The same procedure can be followed to automate a garden’s watering system.

Infrared Obstacle Sensor

The following sensor will probably amuse robotics enthusiasts the most. As the name suggests, the Infrared Obstacle Sensor helps a mobile device intelligently avoid collisions with obstacles. It is popularly used in robots, smart cars, smart drones, etc.

Let us become familiar with the technicalities of this sensor. The IR Infrared Obstacle Sensor comes with an in-built IR transmitter and IR receiver. The transmitter emits IR energy while the receiver registers the IR energy reflected from any obstacle. The sensor can detect obstacles two to thirty centimeters away. The sensor board also has an in-built potentiometer, which allows the users to adjust the detection range according to their liking. The best part about these sensors is that they function conveniently in radiantly bright or pitch-dark environments. The sensor discussed here usually has three pins — the VCC, the GND, and the output. It also comes with two LEDs. One indicates power, while the other implies obstacle detection.

HC-SR501 PIR Motion Sensor

The next infrared-related sensor we have is the Passive Infrared Motion Sensor. Instead of avoiding obstacles while moving, this sensor detects movements. It is most commonly used in security alarm projects. You can also use it while setting up fences and traps to be alerted in case of an intruder. PIR motion sensors are also applicable to light or water dispensing systems. All-in-all, this sensor is an enjoyable one to experiment with. The HC-SR501 PIR Motion Sensor is an excellent choice for anyone to use for its durability and accuracy.

How does this work? The PIR motion sensor measures infrared light initially emitted from objects within its field of view. The sensor is designed to detect any changes in the infrared light of the environment. Be it weak or strong, as long it is within its range, the sensor will keep up any IR energy.

Let us understand the technicalities of the PIR motion sensor as well. The sensor has two in-built potentiometers to adjust the delay time and the sensitivity. The sensor only has three pins – the GND, the OUT, and 5V.

We suggest you use this sensor for is the Night Security Light project. For this project, you will need the HC-SR501 PIR Motion Sensor, the Arduino UNO, a photoresistor, a 10-kiloohm resistor, a relay module, lamp cord, breadboard, and few jumper wires. As for the pinout, GND connects with the ground, OUT connects with any digital pin, while the sensor’s 5V connects with the Arduino’s 5V. The night security light only turns on when movement is detected in the dark, meaning it remains switched off when in daylight or standard house lighting. Imagine waking up blind in front of the darkness in your room to get a glass of water. The moment you step off your bed, the night security light gently glows beneath your bed.

BME680 Environmental Sensor

The BME680 Environmental Sensor by Adafruit is a beast amongst Arduino Sensors. It is a four-in-one environmental digital sensor that measures and monitors gas, pressure, humidity, and temperature. The sensor communicates with the Arduino microcontroller using I2C or SPI communication protocols. Hence, it offers exceptional flexibility in setting up its users. This particular sensor is the perfect candidate for extensive farming projects or greenhouse. Of course, you can utilize it to monitor the conditions of your lovely backyard garden as well.

The BME680 contains a MOX (Metal-oxide) sensor that detects Volatile Organic Compounds (VOCs) like ethanol or carbon monoxide in the air. The sensor provides the user with a qualitative sum of contaminants in sees in your environment. However, it cannot detect specific gas molecules. As for air pressure, the sensor records air pressure from 300 to 1100 hPa with an accuracy of +/-1 hPa. The humidity levels are accurate up to +/-3 percent. Lastly, the sensor measures temperate from -40 to 85 degrees Celsius with an accuracy of +/-1.0 degrees Celsius. It cannot measure temperature in Kelvin or Fahrenheit.

Essentially, each of the four in-built sensors reacts to changes in gas, temperature, pressure, and humidity by decreasing or increasing the resistance. Changes in resistance signal a particular message to the Arduino and adjust the readings accordingly. The pinout for the environment sensor is quite different from the previous sensors we studied. The sensor comes with a VCC, GND, SCL, SDA, SDO, and CS pin. The pinout is different for each of the two protocols: the I2C and the SPI communication. While this sensor may offer many functionalities, it more challenging to set up. Luckily, Adafruit and other third-party platforms have clouded the internet with guides to facilitate you. With a little bit of effort, you should be able to automate your gardening system to a whole new level!

With the help of this blog, we hope you were not only introduced but familiarized with these wonderful Arduino-compatible sensors. All that is left is to pick anyone that you find the most fascinating and start experimenting. Remember, these are only four out of hundreds of Arduino sensors. Keep exploring once you master these. Keep tinkering with Arduinos.

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