CPE241 Week 3 • Computer Engineer

Sensors and actuators

Sensors and actuators are fundamental components in various systems, especially in automation, robotics, and electronics. Here’s a brief overview of each:

Sensors

Definition: Sensors are devices that detect and measure physical properties or environmental conditions and convert them into signals or data that can be read and interpreted by other systems.
Function: Sensors collect information about the surrounding environment or the status of a system. They can measure a wide range of variables such as temperature, pressure, light, motion, humidity, and more.

Examples:

Temperature Sensor: Measures temperature and converts it into an electrical signal.
Proximity Sensor: Detects the presence or absence of an object within a certain range.
Light Sensor: Measures light intensity and provides data that can be used to adjust lighting systems.

Actuators

Definition: Actuators are devices that take signals or commands from a control system and convert them into physical action or movement.
Function: Actuators execute commands to change the state of a system based on the input received, such as moving a part, opening a valve, or adjusting a position.

Examples:

Electric Motor: Converts electrical energy into rotational motion.
Solenoid: Uses an electromagnetic field to create linear motion.
Hydraulic Actuator: Uses hydraulic fluid to produce movement in a hydraulic system.

Relationship Between Sensors and Actuators

Sensors provide the data or feedback that informs the control system about the current state or conditions of a system.
Actuators perform actions based on the control signals or commands derived from sensor data.

In a typical automated system, sensors gather information about the environment or system state, and this data is processed by a controller. The controller then sends commands to actuators to perform specific actions, thereby adjusting or controlling the system as needed.

Project 1

DHT22

Pinout of DHT22:

VCC: Connect to 5V
GND: Connect to GND
DATA: Connect to a digital pin on the borad (e.g., pin 2)
NC: No connection (this pin is not used)

Install the DHT Sensor Library:

Go to the Arduino IDE.
Navigate to Sketch > Include Library > Manage Libraries.
Search for DHT sensor library by Adafruit and install it.
Search for Adafruit Unified Sensor by Adafruit and install it.

#include "DHT.h"

#define DHTPIN D4
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  dht.begin();
}

void loop() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  float f = dht.readTemperature(true);

  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print("% Temperature: ");
  Serial.print(t);
  Serial.print("°C ");
  Serial.print(f);
  Serial.println("°F");

  delay(2000);

}

Project 2

HR-SR04 Ultrasonic Sensors

Pinout of HC-SR04

VCC: Connect to 5V
GND: Connect to GND
TRIG: Trigger pin to send the pulse
ECHO: Echo pin to receive the pulse

#define trigPin D4
#define echoPin D3

long duration;
long distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(115200);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = duration / 58;

  Serial.print("Distance : ");
  Serial.println(distance);
  delay(2000);
}

Project 3

LDR Light sensor analog

Pin of LDR :

One side of the LDR goes to 3.3V (VCC) of the ESP8266.
One side of the fixed resistor connects to the GND (Gnd) pin on the ESP8266.
The other side of the LDR connects to one side of the fixed resistor and also to the Analog input pin (A0) of the ESP8266.

#define LDR A0

void setup() {
  pinMode(LDR, INPUT);
  Serial.begin(115200);
}
void loop() {
  int dt;
  dt = analogRead(LDR);
  Serial.print("intensity = ");
  Serial.println(dt);

  delay(1000);
}

Project 4

Light Sensor BH1750

Pin of Connections for BH1750

VCC to 3.3V (or 5V if your sensor supports it, but using 3.3V is safer for the ESP8266).
GND to GND on the ESP8266.
SDA to D2 (GPIO4) on the ESP8266.
SCL to D1 (GPIO5) on the ESP8266.

Install the DHT Sensor Library:

Go to the Arduino IDE.
Navigate to Sketch > Include Library > Manage Libraries.
Search for BH1750 by Christopher Laws and install it.

#include <Wire.h>
#include <BH1750.h>

BH1750 lightMeter;

#define SDA D2
#define SCL D1

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA, SCL);
  lightMeter.begin();
}
void loop() {
  float lux = lightMeter.readLightLevel();
  Serial.print("Light: ");
  Serial.print(lux);
  Serial.println(" lx");
  delay(1000);
}

Compare

LDR Light sensor analog vs BH1750

#include <Wire.h>
#include <BH1750.h>
BH1750 lightMeter;

#define SDA D2
#define SCL D1
#define LDR A0

void setup() {
  pinMode(LDR, INPUT);
  Serial.begin(115200);
  Wire.begin(SDA, SCL);
  lightMeter.begin();
}
void loop() {
  int dt;
  dt = analogRead(LDR);
  Serial.print("dt = ");
  Serial.print(dt);

  float lux = lightMeter.readLightLevel();
  Serial.print(" ,Lux: ");
  Serial.println(lux);


  delay(1000);
}