PROJECT V : OLED Display and PWM Signal

Welcome to my fifth project of ESP32. This project is a form of implementation of the knowledge that i got from Embedded System course. In this next project, we’re going to learn to use an External Display OLED and PWM Signal on ESP32.

#Required Components/Hardware

First things first we need to know what components are needed for this project. These components are just the examples I used for this project, you can use different types of components that you can find easily on the internet.

  1. ESP32 Development Kit
  2. Male to Male Wire Cable
  3. Micro USB Cable
  4. Breadboard
  5. LED Lamp
  6. Resistor 330 ohm
  7. OLED Display

#Required Software

In this project we use an external OLED Display, so we need to install another library for this OLED Display. You can go to Tools -> Manage Libraries, then search Adafruit SSD1306. Click Install -> Install All.

After that you also need to install GFX. Search Adafruit GFX Library then select the latest version and click Install > Install all.

#Assembling The Circuit

Source : randomnerdtutorials.com

You need to connect the OLED to the ESP32. The connection is pretty simple and if you assemble on the Breadboard, it should look like this

And now for a simple experiment, we can print text to the OLED. Since this week is the exam week in ITB, I want to cheer up my friends for the exam. So i use this code,

/*********
Rui Santos
Complete project details at https://randomnerdtutorials.com
*********/
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64// OLED display height, in pixels
// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
void setup() {
Serial.begin(115200);
if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
Serial.println(F("SSD1306 allocation failed"));
for(;;);
}
delay(2000);
display.clearDisplay();
display.setTextSize(1.5);
display.setTextColor(WHITE);
display.setCursor(0, 10);
// Display static text
display.println("Haii..");
display.println("");
display.println("Semangat UTSnya Yahh");
display.println("Wahai Kalian");
display.println("Manusia Hebat");
display.display();
}
void loop() {
}

If you try to upload the code, your OLED should look like this

#Creativity

Now, we’re going to print another form of information. In this exploration i want to display and Image and do a little bit of modification. I use this website to convert an image. Make sure to set the canvas size to 128x64 pixels.

And this is the code that i use,

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
const unsigned char fotoBitmap [] PROGMEM = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xe0, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0f, 0xf8, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x1f, 0xfe, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x0f, 0xfc, 0x3f, 0xff, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x07, 0xfc, 0x3f, 0xff, 0x80, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x03, 0xf8, 0x3f, 0xff, 0xc0, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x01, 0xf8, 0x3f, 0xff, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0xf8, 0x7e, 0xff, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0xf0, 0x7c, 0xff, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0xf0, 0xe0, 0xf7, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0xf1, 0x80, 0xe7, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0xe3, 0x00, 0xe3, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0xc6, 0x01, 0xe1, 0xc0, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0xc6, 0x03, 0xe1, 0x80, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x01, 0xc7, 0x1f, 0xe1, 0x80, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x03, 0xc3, 0xff, 0xe1, 0x80, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x07, 0xc3, 0xff, 0xe0, 0x80, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x07, 0xc3, 0xf8, 0xe0, 0xc0, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x0f, 0xc0, 0xf8, 0x70, 0xc0, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x0f, 0xc0, 0x7f, 0x3f, 0xc0, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x03, 0xc0, 0x7f, 0xff, 0xc0, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x03, 0xc0, 0xff, 0xff, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x03, 0xff, 0xc0, 0xe3, 0xff, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x03, 0xff, 0xc0, 0xc1, 0xfe, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x03, 0x9f, 0xc0, 0xc0, 0xfe, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x03, 0x9f, 0xc0, 0x80, 0xfc, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x1f, 0x80, 0x00, 0xf8, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x1f, 0x81, 0x80, 0xf0, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x9f, 0x01, 0x80, 0xe0, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x80, 0x01, 0x81, 0xc0, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x01, 0x81, 0x80, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x01, 0x81, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x80, 0x01, 0x82, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x80, 0x01, 0x82, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x80, 0x01, 0x80, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x80, 0x00, 0x04, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x01, 0x80, 0x02, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x80, 0x02, 0x10, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x02, 0x20, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x03, 0xe0, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x01, 0xe0, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0xc0, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};
// Array of all bitmaps for convenience. (Total bytes used to store images in PROGMEM = 205008)
const int epd_bitmap_allArray_LEN = 1;
const unsigned char* epd_bitmap_allArray[1] = {
fotoBitmap
};
void setup() {
Serial.begin(115200);

if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;);
}
delay(2000); // Pause for 2 seconds

// Clear the buffer.
display.clearDisplay();
//draw it!
display.setTextSize(1);
display.setTextColor(WHITE);
display.setCursor(0,20);
display.println("Knock knock...");
display.display();
delay(3000);
display.println("Wh.. Who's There?");
display.display();
delay(3000);
display.println("He..Hello..?");
display.display();
delay(3000);
display.clearDisplay();
display.println(" BEHIND YOU");
display.display();
delay(1000);
display.clearDisplay();
display.drawBitmap(0,0,fotoBitmap, 128,64,1);
display.display();
}
void loop() {
}

Compile the code to make sure that the code has no error. Upload the code by clicking the right arrow at the left-top screen and holding the boot button at the ESP32 during the uploading process. Wait until the loading finish. If the terminal shows a “Done uploading” message, then your code is already uploaded to the ESP32.

The result will look like this,

#ESP32 PWM Signal

Based on arduino.cc, Pulse Width Modulation or PWM, is a technique for getting analog results with digital means. Digital control is used to create a square wave, a signal switched between on and off. Now we’re going to try to generate PWM signals with the ESP32 using Arduino IDE. Let’s use the schematic below for this PWM tutorial,

And this is how it looks like on the breadboard,

And to test the PWM Signal, paste this code and upload it to the ESP32,

And so that’s my experience in working on the fifth project. Thank you for reading this article and I hope this article can be helpful for people who want to start trying to learn ESP32.

Rayhan Naufal Luthfi
Information System Technology ITB 2020
18220048

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