Can one talk about a controller without talking about sensing?
The beauty of the IoT (Internet Of Things) is that we can automate things and have them perform without us always needing to intervene in the process. Where the need of sensors, that will play the role of eyes to the controlling part of the system.
What is a sensor?
Wikipekia says it best: “A sensor is an object whose purpose is to detect events or changes in its environment, and then provide a corresponding output”.
Why do we need sensor?
A sensor is the guy who provides data to the a system via its input. Say you set your air conditioning system to bring the room temperature to 15 degrees, considering it was previously off (and the current temperature of the room is different that 15 degrees), now the system starts pumping air to bring the room to the desired temperature, how does it know when the room temperature has been reached?
Here is where the sensor comes into play: there must be a sensor in the room to tell the air-conditioning system to stop pumping when the wanted temperature is attained. That is roughly it.
We need sensor to feed data to the system and tells the controller when to take action
If you are building an arduino powered car that will avoid obstacle while cruising, you could for example make use of a collision crash sensor to tell the controller when an obstacle is ahead of the car, then the controller can tell the wheel to stop and move to a different direction.
The following are some variety of sensors you can make used of when working with an arduino boards.
Most used sensors for Arduino
|Temperature + humidity sensor||This is a temperature/humidity sensor. You can use this Arduino compatible sensor to monitor the ambient temperature or humidity. As a basic project, you can plug an LCD to Arduino and have it display the room temperature/humidity.|
|Infrared emission sensor||This is an infrared emission sensor, also called "infrared emitting diode". It works at 38KHz modulating signal. This sensor can be used to send code to another Arduino or control a TV.|
|Photoresistor||This a Photo Light Sensitive Resistor. The resistance of the component will vary with intensity of light to which it is exposed. Explained in simple term we will say that this sensor is a resistor whose resistance goes down when light hits it.|
|Ultrasonic Distance sensor||This sensor automatically sends an audio signal of 40 kHz and detect whether there is a pulse signal back. It sends a signal and if received back it computes the distance traveled by the signal, thus the distance from the sensor to the object in front of the it. It can sense an object in the range: 2cm~500cm|
|Knock sensor||In simple terms, this is a switch that turns on when it detects a knock. There is an LED that alternatively gives a visual signal of the state of the sensor, high or low, and the high level designated by the LED turning on.|
|Sound sensor||This is a sensor that will detect the surrounding sound, and it has a adjustable sensitivity. This is best used for projects such as voice changers.|
|Voltage (over/under) detection||This sensor detects the voltage level of any DC voltage supplier, up to 25 volts. Critical points of over-voltage / under-voltage can be adjusted.|
|Heart rate pulse sensor (pulsesensor)||This sensor helps sense Pulse Heart Rate. The Operating Voltage is 3V / 5V; The Amplification factor: 330. This sensor can be used to track/plot heart beats.|
|magnetic reed sensor for Arduino||This sensor helps sense the presence of magnetic fields. When a magnetic substance approaches, the switch senses the magnetic field and is electrified; thus, the module outputs low level. When there is not magnet approaching, the module is de-energized and will output high|
|Optical fingerprint sensor||This sensor helps to detect, record or verify finger-prints. This can help you enroll new fingers directly. Up to 162 finger-prints can be stored in the onboard FLASH memory|
|Comparator speed sensor||This sensor is mostly used in the motor speed detection, pulse count. As his name says, it helps sense speed differences.|
|Alcohol Gas Sensor Detector for Arduino||This sensor senses the presence of alcohol Gas in the air. The detection range is 10 to 1000ppm. Detecting Type: Alcohol, Ethanol|
|Water sensor||This sensor is used for water detection and can be used in project where like: sensing the rainfall, water level, water leakage, Tank overflow detector. This sensor can easily convert the water size to analog signal, and the output analog value can directly be used in the program function, then to achieve a desire function.|
|Collision crack sensor||This is a switch that can be used to sense the position of an object, when colliding and switching the trigger of the sensor which you can observe on the image on the side.|
|Line tracking sensor||This sensor tracks line. It is mostly used for projects where you want your robot/car to navigate following a white line of the black background.|
|Infrared motion detection||This is a Pyroelectric IR Infrared sensor for People Detection. I often like testing this sensor by simply using it like a Switch-ON/Swithc-OFF device for an LED, That allows to easily tune its sensitivity and its timing.|
|Flame sensor||This sensor detects the presence of flame and is often be used to detect the presence of light as well. It detects a flame or a light source of a wavelength in the range of 760nm-1100 nm. A light flame test can be triggered within 0.8m. If the intensity of flame is high, the detection distance will be increased|
|Methane CH4 Gas Sensor||This is a Methane propane hydrogen gas sensor for Arduino, great for home or factory gas leakage detection.
This sensor can be used to Detect: Combustible gas such as LPG, butane, methane, alcohol, propane, hydrogen, smoke.
|2.4GHz Wireless Transceiver in Antistatic Foam||This is an important part of a wireless sensor network. It can help control objects wirelessly. This module can be used for projects such as: wireless voice transmission such as VoIP, home automation and wireless networks.|
|Color Sensor||This sensor detects static color and outputs a square wave with frequency directly proportional to incident light intensity. The ideal detection distance is 10mm. This can be used for sorting object by colors.|
|Adafruit Digital Light / Luminosity / Lux sensor||This sensor allows exact lux calculations and can be configured for different gain and timing ranges to detect light ranges from up to 0.1 - 40,000 lux.|
|Adafruit Fast Vibration Sensor Switch||This is a spring-vibration sensor which is high sensitivity non-directional vibration induced trigger switches. Inside is a very soft spring coiled around a long metal pin. When the switch is moved, the two pins will act like a closed switch. When everything is still, the switch is open|
|Adafruit Short Flex/Bend Sensor||This sensor detects bending (in one direction only). It is roughly a resistor that changes its value based on how much it is flexed.|
|Adafruit Barometric Pressure & Altitude Sensor||This sensor can be used for all sort of weather sensing. it helps measure barometric pressure and temperature. This could also be used to build an altimeter.|
|Water Flow Sensor||This sensor can help you build a basic flow meter. It can help measure liquid/water flow. It has pinwheel and a little magnet attached to it, and there's a hall effect magnetic sensor on the other side of the plastic tube that can measure how many spins the pinwheel has made through the plastic wall.|
|Barcode Reader/Scanner Module||This sensor can help you build your own barcode reader/scanner. It brings the benefits of barcode scanning to your Arduino. It uses a compact, long range CCD barcode scanning module with highly sensitive liner image sensor and build in auto-sense function, that can be used in your project to decode nearly any kind of 1D (striped) barcode.|
|Liquid Water Level Sensor Float Switch||This is a sensor that helps sense water level. Just like the water sensor, this can be used to sense the level of water in a container, but this one has a float switch.|
|Adafruit Laser Break Beam Sensor||This is a laser break sensor. It detects an object breaking a laser beam. But you usually have to set up a laser on one end and a sensor on the other. Your sensor needs to be big enough not to go out of alignment with the beam.|