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Lesson 41: Potentiometer scale value

This project focuses on reading a potentiometer’s value and displaying it on an LCD 1620 equipped with an I2C interface. Additionally, the value is transmitted to the serial monitor for live monitoring. A distinctive aspect of this project is the graphical representation of the potentiometer’s value on the LCD, which is depicted as a variable-length bar proportional to the potentiometer’s reading.

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
Potentiometer Module	-
I2C LCD 1602	-
Breadboard	BUY

Wiring

Code

Code Analysis

The core functionality of this project is to consistently read the potentiometer’s value, map it to a scaled range (0-16), and display the result both numerically and graphically on the LCD. The implementation minimizes jitter by updating the display only when significant changes in the reading occur, thus maintaining a smooth visual experience.

1. Library Inclusion and Initialization:

   // Required libraries for I2C and LCD operations
   #include <Wire.h>
   #include <LiquidCrystal_I2C.h>
   
   // Initialize LCD at I2C address 0x27 with 16 columns and 2 rows
   LiquidCrystal_I2C lcd(0x27, 16, 2);
   

   This segment incorporates the necessary libraries for I2C communication and LCD control. It then initializes an LCD instance with the I2C address of 0x27, specifying its dimensions as 16 columns and 2 rows.

2. Variable Declaration:

   // Variables to hold the potentiometer readings
   int lastRead = 0;     // Previous potentiometer value
   int currentRead = 0;  // Current potentiometer value
   

   Variables lastRead and currentRead are used to keep track of the potentiometer’s readings across different moments.

3. setup() Function:

   void setup() {
     lcd.init();          // Initiates the LCD
     lcd.backlight();     // Activates the LCD's backlight
     Serial.begin(9600);  // Commences serial communication at 9600 baud
   }
   

   This function prepares the LCD and starts serial communication, setting up the environment for the project’s operation.

4. Main Loop:

   void loop() {
      // Read the current potentiometer value
      int currentRead = analogRead(35);
   
      // Map the read value from 0-4096 to 0-16
      int barLength = map(currentRead, 0, 4096, 0, 16);
   
      // Update LCD only if the difference between current and last reading is greater than 2 to avoid jitter
      if (abs(lastRead - currentRead) > 2) {
         lcd.clear();
         lcd.setCursor(0, 0);
         lcd.print("Value:");
         lcd.setCursor(7, 0);
         lcd.print(currentRead);
         Serial.println(currentRead);
   
         // Display a bar on the second row of LCD proportional to the potentiometer value
         for (int i = 0; i < barLength; i++) {
            lcd.setCursor(i, 1);
            lcd.print(char(255));
         }
      }
      // Update the last read value for the next iteration
      lastRead = currentRead;
   
      // Introduce a delay for a stable reading
      delay(200);
   }
   

   • Reads the potentiometer and converts its value to a scale suitable for visual representation.

   • Updates the LCD only when a meaningful change is detected, displaying the numeric value and a corresponding bar graph.

   • Also sends the reading to the serial monitor for external observation.

   • Ensures stability and responsiveness by introducing a brief delay between iterations.