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Lesson 37: Automatic soap dispenser

The Automatic Soap Dispenser project uses an Arduino Uno board along with an infrared obstacle avoidance sensor and a water pump. The sensor detects the presence of an object such as a hand, which activates the water pump to dispense soap.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Universal Maker Sensor Kit	94	Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction	Purchase Link
ESP32 & Development Board (ESP32 Board)	BUY
IR Obstacle Avoidance Sensor Module	BUY
Centrifugal Pump	-
L9110 Motor Driver Module	-
Power Supply Module	-
Breadboard	BUY

Wiring

Code

Code Analysis

The main idea behind this project is to create a hands-free soap dispensing system. The infrared obstacle avoidance sensor detects when an object (like a hand) is close. Upon detecting an object, the sensor sends a signal to the Arduino, which in turn triggers the water pump to dispense soap. The pump stays active for a brief period, dispensing soap, then turns off.

1. Defining the pins for the sensor and the pump

   In this code snippet, we define the Arduino pins that connect to the sensor and pump. We define pin 7 as the sensor pin and we will use the variable sensorValue to store the data read from this sensor. For the water pump, we use two pins, 9 and 10.

   // Define the pin numbers for the Infrared obstacle avoidance sensor
   const int sensorPin = 35;
   int sensorValue;
   
   // Define pin numbers for the water pump
   const int pump1A = 19;
   const int pump1B = 21;
   

2. Setting up the sensor and pump

   In the setup() function, we define the modes for the pins we’re using. The sensor pin is set to INPUT as it will be used to receive data from the sensor. The pump pins are set to OUTPUT as they will send commands to the pump. We ensure that the pin pump1B starts in a LOW state (off), and we start the serial communication with a baud rate of 9600.

   void setup() {
       // Set the sensor pin as input
       pinMode(sensorPin, INPUT);
   
       // Initialize the pump pins as output
       pinMode(pump1A, OUTPUT);
       pinMode(pump1B, OUTPUT);
   
       // Keep pump1B low
       digitalWrite(pump1A, LOW);
       digitalWrite(pump1B, LOW);
   
       Serial.begin(9600);
   }
   

3. Continuously checking the sensor and controlling the pump

   In the loop() function, the Arduino constantly reads the value from the sensor using digitalRead() and assigns it to sensorValue(). It then prints this value to the serial monitor for debugging purposes. If the sensor detects an object, sensorValue() will be 0. When this happens, pump1A is set to HIGH, activating the pump, and a delay of 700 milliseconds allows the pump to dispense soap. The pump is then deactivated by setting pump1A to LOW, and a 1-second delay gives the user time to move their hand away before the cycle repeats.

   Note

   If the sensor is not working properly, adjust the IR transmitter and receiver to make them parallel. Additionally, you can adjust the detection range using the built-in potentiometer.

   void loop() {
       sensorValue = digitalRead(sensorPin);
       Serial.println(sensorValue);
   
       // If an object is detected, turn on the pump for a brief period, then turn it off
       if (sensorValue == 0) {
           digitalWrite(pump1A, HIGH);
           delay(700);
           digitalWrite(pump1A, LOW);
           delay(1000);
       }
   }