Questions You Should Know about 0 42 inch pm oled display

How much current do OLED displays use?

Those little OLED displays are everywhere, and there's a good reason. They're inexpensive, easy to program and they look good. I wanted to explore how much current they draw so that I can plan better for battery powered projects.

Questions I want answered:

• How much idle current is drawn when the controller is off versus on (blank display)?
• What's the minimum current to see text indoors?
• What's the maximum current when all pixels are on at their brightest?
• How does display size affect current draw?
• How does active data writing affect current draw?
• It's obvious they use more, but how much current do grayscale and color OLEDs use?
• How practical are OLED displays compared to common LCDs for battery powered projects?

Materials:

• Cheap multimeter (manual scale, assumed accuracy +/-10% at worst)
• Various OLED displays (72x40, 96x16, 128x32, 64x32, 128x64-0.96", 128x64-1.3")
• Arduino compatible microcontroller (Adafruit nRF Feather Express)
• Software (my ss_oled library)

These are the displays I used for my tests. I like to use the I2C breakout board versions for simplicity. There may be inefficiencies in the linear regulator and other discrete components which come on the breakout boards, but since the active displays use milliamps, losing a few microamps shouldn't be a big deal.

What about color and grayscale OLED displays?
I was asked on twitter to include a quick test of these OLED displays. I could tell that the power usage was high because the controller chip gets hot to the touch when barely anything is displayed. I no longer have my SSD color OLED to test, but I do have an SSD 128x128 4-bit grayscale display. With the display set to 'off', I measured 600uA. Here are some values I measured when the contrast (brightness) was set to the maximum value:

Display filled with color 0  - 2.5mA (every pixel is off/black)
Display filled with color 1  - 85mA
Display filled with color 2  - 111mA
Display filled with color 3  - 147mA
Display filled with color 15 (display reset due to my 3.3v power supply sagging)

In general, the display uses a lot more current to get the same pixel brightness compared to the monochrome SSD displays.

Procedure:
I ran 8 different tests on each display. The "dim" setting has the contrast set at a value of 31. This is comfortable to read in indoor light or at night. 127 is the default contrast and is reasonably bright. 255 is the max brightness. The current was measured by inserting the multimeter probes between the Vcc of the display and a 3.3V power source (in this case, the regulated output of the Arduino). There was very little visible difference between contrast 1 and 31.

Results:

Type Display Off On, but Black Contrast 31, 50% pixels lit Contrast 127, 50% pixels lit Contrast 255, 50% pixels lit Contrast 31, 100% pixels lit Contrast 127, 100% pixels lit Contrast 255, 100% pixels lit 128x128 1.12' 5mA 7.1mA 49.5mA 104.0mA 108.0mA 89.9mA 104.0mA 104.0mA 128x64 1.3' 490uA 490uA 15.4mA 26.1mA 31.4mA 20.6mA 33.7mA 39.1mA 128x64 0.96' 26uA 469uA 5.6mA 8.1mA 11.0mA 10.3mA 15.1mA 20.7mA 128x32 0.91' 6uA 6uA 12.1mA 16.2mA 21.1mA 21.3mA 29.0mA 38.7mA 128x32 0.91' 4uA 4uA 16.2mA 19.7mA 21.7mA 27.5mA 33.8mA 36.0mA 96x16 0.69' 7uA 7uA 4.45mA 5.62mA 6.96mA 7.23mA 9.44mA 12.11mA 64x32 0.49' 6uA 6uA 1.56mA 2.71mA 3.11mA 2.49mA 4.63mA 5.17mA 72x40 0.42' 4uA 230uA* 630uA* N/A N/A 93 N/A N/A * The 72x40 display didn't appear to respond to the contrast setting and had a permanent and somewhat dim contrast.
* The 128x128 display is sold by Pimoroni; I don't have other examples to test

I thought that the 128x32 was an anomaly from a specific vendor, but a second display from a different vendor behaved the same way. Strangely, a second 64x32 display from the same vendor, bought in the same batch, used twice as much power as the one tested above.

I chose the most efficient display to do a final test which displays text (less than 50% pixel coverage). My ammeter read 630uA for a static text display on the 64x32 OLED.


What about active data writing?
Besides extra activity on the display controller, there will be current leaking through the pullup resistors when the SCL or SDA lines go low. Typical pullup resistors for these displays are 4.7KOhm, so while the data and clock lines are active, about 700uA (3.3V / ohms) will leak through them. I tried a test where I continuously wrote the same data to the display (same display and same text as above). The results were a reading of 1.47mA. Different pullup resistors and different data being written will produce different results.

Conclusions:

• There is a nearly linear relationship between the number of lit pixels and current use
• The display size is directly related to the current use
• There are some oddball displays that use more current than expected. Need to test each one individually
• Actively writing to the display uses more current than a static display - hard to know if it's the I2C activity or the controller chip or both
• There's something odd about the 72x40 displays I have; I will need to get some from another vendor and retest
• The ubiquitous 128x64 0.96" OLEDs can potentially display a screen full of useful information on less than 5mA
• The power usage of grayscale and color OLEDs is much less efficient when compared to the same size and brightness of monochrome displays.
• A small OLED with indoor readable text can run on less than 1mA

The last item above surprised me the most. The power indicator LED on most Arduino boards uses more current than the 64x32 OLED with useful information displayed on it.
To answer my last question about the practicality of OLEDs versus commonly available LCDs for battery powered projects, I think it depends on the project and power source. A decent sized LCD with the backlight off can consume less than 275uA (my measurements from a 2" 128x64 UC). If your power budget is small and your MCU is programmed to sleep most of the time (avg current < 1mA), this can make a huge difference compared to a 5-20mA OLED displaying the same info. On the other hand, if you're powering a Raspberry Pi Zero or ESP32 w/WIFI on (80-120mA), another 5-20mA won't make as big a difference to your power budget.
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This article shows how to use the SSD 0.96 inch I2C OLED display with the Arduino. We'll show you some features of the OLED display, how to connect it to the Arduino board, and how to write text, draw shapes and display bitmap images. Lastly, we'll build a project example that displays temperature and humidity readings.

For more information, please visit ORIC Electronics.

Introducing the 0.96 inch OLED display

The organic light-emitting diode (OLED) display that we'll use in this tutorial is the SSD model: a monocolor, 0.96-inch display with 128×64 pixels as shown in the following figure.

The OLED display doesn't require backlight, which results in a very nice contrast in dark environments. Additionally, its pixels consume energy only when they are on, so the OLED display consumes less power when compared with other displays.

The model we're using here has only four pins and communicates with the Arduino using I2C communication protocol. There are models that come with an extra RESET pin. There are also other OLED displays that communicate using SPI communication.

Pin wiring

Because the OLED display uses I2C communication protocol, wiring is very simple. You just need to connect to the Arduino Uno I2C pins as shown in the table below.

If you're using a different Arduino board, make sure you check the correct I2C pins:

• Nano: SDA (A4); SCL (A5);
• MEGA: SDA (20); SCL (21);
• Leonardo: SDA (20); SCL (21);

Libraries

To control the OLED display you need the adafruit_SSD.h and the adafruit_GFX.h libraries. Follow the next instructions to install those libraries.

1. Open your Arduino IDE and go to Sketch > Include Library > Manage Libraries. The Library Manager should open.

2. Type 'SSD' in the search box and install the SSD library from Adafruit.

3. After installing the SSD library from Adafruit, type 'GFX' in the search box and install the library.

4. After installing the libraries, restart your Arduino IDE.

Tips for writing text using these libraries

Here's some functions that will help you handle the OLED display library to write text or draw simple graphics.

• display.clearDisplay() ' all pixels are off
• display.drawPixel(x,y, color) ' plot a pixel in the x,y coordinates
• display.setTextSize(n) ' set the font size, supports sizes from 1 to 8
• display.setCursor(x,y) ' set the coordinates to start writing text
• display.print('message') ' print the characters at location x,y
• display.display() ' call this method for the changes to make effect

Testing the OLED Display

After wiring the OLED display to the Arduino and installing all required libraries, you can use one example from the library to see if everything is working properly.

In your Arduino IDE, go to File > Examples > Adafruit SSD and select the example for the display you're using.

The following code should load:

/*********
  Complete project details at https://randomnerdtutorials.com
  
  This is an example for our Monochrome OLEDs based on SSD drivers. Pick one up today in the adafruit shop! ------> http://www.adafruit.com/category/63_98
  This example is for a 128x32 pixel display using I2C to communicate 3 pins are required to interface (two I2C and one reset).
  Adafruit invests time and resources providing this open source code, please support Adafruit and open-source hardware by purchasing products from Adafruit!
  Written by Limor Fried/Ladyada for Adafruit Industries, with contributions from the open source community. BSD license, check license.txt for more information All text above, and the splash screen below must be included in any redistribution. 
*********/

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define NUMFLAKES     10 // Number of snowflakes in the animation example

#define LOGO_HEIGHT   16
#define LOGO_WIDTH    16
static const unsigned char PROGMEM logo_bmp[] =
{ B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B,
  B, B };

void setup() {
  Serial.begin();

  // SSD_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  // Show initial display buffer contents on the screen --
  // the library initializes this with an Adafruit splash screen.
  display.display();
  delay(); // Pause for 2 seconds

  // Clear the buffer
  display.clearDisplay();

  // Draw a single pixel in white
  display.drawPixel(10, 10, WHITE);

  // Show the display buffer on the screen. You MUST call display() after
  // drawing commands to make them visible on screen!
  display.display();
  delay();
  // display.display() is NOT necessary after every single drawing command,
  // unless that's what you want...rather, you can batch up a bunch of
  // drawing operations and then update the screen all at once by calling
  // display.display(). These examples demonstrate both approaches...

  testdrawline();      // Draw many lines

  testdrawrect();      // Draw rectangles (outlines)

  testfillrect();      // Draw rectangles (filled)

  testdrawcircle();    // Draw circles (outlines)

  testfillcircle();    // Draw circles (filled)

  testdrawroundrect(); // Draw rounded rectangles (outlines)

  testfillroundrect(); // Draw rounded rectangles (filled)

  testdrawtriangle();  // Draw triangles (outlines)

  testfilltriangle();  // Draw triangles (filled)

  testdrawchar();      // Draw characters of the default font

  testdrawstyles();    // Draw 'stylized' characters

  testscrolltext();    // Draw scrolling text

  testdrawbitmap();    // Draw a small bitmap image

  // Invert and restore display, pausing in-between
  display.invertDisplay(true);
  delay();
  display.invertDisplay(false);
  delay();

  testanimate(logo_bmp, LOGO_WIDTH, LOGO_HEIGHT); // Animate bitmaps
}

void loop() {
}

void testdrawline() {
  int16_t i;

  display.clearDisplay(); // Clear display buffer

  for(i=0; i<display.width(); i+=4) {
    display.drawLine(0, 0, i, display.height()-1, WHITE);
    display.display(); // Update screen with each newly-drawn line
    delay(1);
  }
  for(i=0; i<display.height(); i+=4) {
    display.drawLine(0, 0, display.width()-1, i, WHITE);
    display.display();
    delay(1);
  }
  delay(250);

  display.clearDisplay();

  for(i=0; i<display.width(); i+=4) {
    display.drawLine(0, display.height()-1, i, 0, WHITE);
    display.display();
    delay(1);
  }
  for(i=display.height()-1; i>=0; i-=4) {
    display.drawLine(0, display.height()-1, display.width()-1, i, WHITE);
    display.display();
    delay(1);
  }
  delay(250);

  display.clearDisplay();

  for(i=display.width()-1; i>=0; i-=4) {
    display.drawLine(display.width()-1, display.height()-1, i, 0, WHITE);
    display.display();
    delay(1);
  }
  for(i=display.height()-1; i>=0; i-=4) {
    display.drawLine(display.width()-1, display.height()-1, 0, i, WHITE);
    display.display();
    delay(1);
  }
  delay(250);

  display.clearDisplay();

  for(i=0; i<display.height(); i+=4) {
    display.drawLine(display.width()-1, 0, 0, i, WHITE);
    display.display();
    delay(1);
  }
  for(i=0; i<display.width(); i+=4) {
    display.drawLine(display.width()-1, 0, i, display.height()-1, WHITE);
    display.display();
    delay(1);
  }

  delay(); // Pause for 2 seconds
}

void testdrawrect(void) {
  display.clearDisplay();

  for(int16_t i=0; i<display.height()/2; i+=2) {
    display.drawRect(i, i, display.width()-2*i, display.height()-2*i, WHITE);
    display.display(); // Update screen with each newly-drawn rectangle
    delay(1);
  }

  delay();
}

void testfillrect(void) {
  display.clearDisplay();

  for(int16_t i=0; i<display.height()/2; i+=3) {
    // The INVERSE color is used so rectangles alternate white/black
    display.fillRect(i, i, display.width()-i*2, display.height()-i*2, INVERSE);
    display.display(); // Update screen with each newly-drawn rectangle
    delay(1);
  }

  delay();
}

void testdrawcircle(void) {
  display.clearDisplay();

  for(int16_t i=0; i<max(display.width(),display.height())/2; i+=2) {
    display.drawCircle(display.width()/2, display.height()/2, i, WHITE);
    display.display();
    delay(1);
  }

  delay();
}

void testfillcircle(void) {
  display.clearDisplay();

  for(int16_t i=max(display.width(),display.height())/2; i>0; i-=3) {
    // The INVERSE color is used so circles alternate white/black
    display.fillCircle(display.width() / 2, display.height() / 2, i, INVERSE);
    display.display(); // Update screen with each newly-drawn circle
    delay(1);
  }

  delay();
}

void testdrawroundrect(void) {
  display.clearDisplay();

  for(int16_t i=0; i<display.height()/2-2; i+=2) {
    display.drawRoundRect(i, i, display.width()-2*i, display.height()-2*i,
      display.height()/4, WHITE);
    display.display();
    delay(1);
  }

  delay();
}

void testfillroundrect(void) {
  display.clearDisplay();

  for(int16_t i=0; i<display.height()/2-2; i+=2) {
    // The INVERSE color is used so round-rects alternate white/black
    display.fillRoundRect(i, i, display.width()-2*i, display.height()-2*i,
      display.height()/4, INVERSE);
    display.display();
    delay(1);
  }

  delay();
}

void testdrawtriangle(void) {
  display.clearDisplay();

  for(int16_t i=0; i<max(display.width(),display.height())/2; i+=5) {
    display.drawTriangle(
      display.width()/2  , display.height()/2-i,
      display.width()/2-i, display.height()/2+i,
      display.width()/2+i, display.height()/2+i, WHITE);
    display.display();
    delay(1);
  }

  delay();
}

void testfilltriangle(void) {
  display.clearDisplay();

  for(int16_t i=max(display.width(),display.height())/2; i>0; i-=5) {
    // The INVERSE color is used so triangles alternate white/black
    display.fillTriangle(
      display.width()/2  , display.height()/2-i,
      display.width()/2-i, display.height()/2+i,
      display.width()/2+i, display.height()/2+i, INVERSE);
    display.display();
    delay(1);
  }

  delay();
}

void testdrawchar(void) {
  display.clearDisplay();

  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.cp437(true);         // Use full 256 char 'Code Page 437' font

  // Not all the characters will fit on the display. This is normal.
  // Library will draw what it can and the rest will be clipped.
  for(int16_t i=0; i<256; i++) {
    if(i == '\n') display.write(' ');
    else          display.write(i);
  }

  display.display();
  delay();
}

void testdrawstyles(void) {
  display.clearDisplay();

  display.setTextSize(1);             // Normal 1:1 pixel scale
  display.setTextColor(WHITE);        // Draw white text
  display.setCursor(0,0);             // Start at top-left corner
  display.println(F("Hello, world!"));

  display.setTextColor(BLACK, WHITE); // Draw 'inverse' text
  display.println(3.);

  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(WHITE);
  display.print(F("0x")); display.println(0xDEADBEEF, HEX);

  display.display();
  delay();
}

void testscrolltext(void) {
  display.clearDisplay();

  display.setTextSize(2); // Draw 2X-scale text
  display.setTextColor(WHITE);
  display.setCursor(10, 0);
  display.println(F("scroll"));
  display.display();      // Show initial text
  delay(100);

  // Scroll in various directions, pausing in-between:
  display.startscrollright(0x00, 0x0F);
  delay();
  display.stopscroll();
  delay();
  display.startscrollleft(0x00, 0x0F);
  delay();
  display.stopscroll();
  delay();
  display.startscrolldiagright(0x00, 0x07);
  delay();
  display.startscrolldiagleft(0x00, 0x07);
  delay();
  display.stopscroll();
  delay();
}

void testdrawbitmap(void) {
  display.clearDisplay();

  display.drawBitmap(
    (display.width()  - LOGO_WIDTH ) / 2,
    (display.height() - LOGO_HEIGHT) / 2,
    logo_bmp, LOGO_WIDTH, LOGO_HEIGHT, 1);
  display.display();
  delay();
}

#define XPOS   0 // Indexes into the 'icons' array in function below
#define YPOS   1
#define DELTAY 2

void testanimate(const uint8_t *bitmap, uint8_t w, uint8_t h) {
  int8_t f, icons[NUMFLAKES][3];

  // Initialize 'snowflake' positions
  for(f=0; f< NUMFLAKES; f++) {
    icons[f][XPOS]   = random(1 - LOGO_WIDTH, display.width());
    icons[f][YPOS]   = -LOGO_HEIGHT;
    icons[f][DELTAY] = random(1, 6);
    Serial.print(F("x: "));
    Serial.print(icons[f][XPOS], DEC);
    Serial.print(F(" y: "));
    Serial.print(icons[f][YPOS], DEC);
    Serial.print(F(" dy: "));
    Serial.println(icons[f][DELTAY], DEC);
  }

  for(;;) { // Loop forever...
    display.clearDisplay(); // Clear the display buffer

    // Draw each snowflake:
    for(f=0; f< NUMFLAKES; f++) {
      display.drawBitmap(icons[f][XPOS], icons[f][YPOS], bitmap, w, h, WHITE);
    }

    display.display(); // Show the display buffer on the screen
    delay(200);        // Pause for 1/10 second

    // Then update coordinates of each flake...
    for(f=0; f< NUMFLAKES; f++) {
      icons[f][YPOS] += icons[f][DELTAY];
      // If snowflake is off the bottom of the screen...
      if (icons[f][YPOS] >= display.height()) {
        // Reinitialize to a random position, just off the top
        icons[f][XPOS]   = random(1 - LOGO_WIDTH, display.width());
        icons[f][YPOS]   = -LOGO_HEIGHT;
        icons[f][DELTAY] = random(1, 6);
      }
    }
  }
}

View raw code

If your OLED doesn't have a RESET pin, you should set the OLED_RESET variable to -1 as shown below:

#define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)

Upload the code to your Arduino board. Don't forget to select the right board and COM port in the Tools menu.

You should get a series of different animations in the OLED as shown in the following short video.

If your OLED display is not showing anything:

• Check that the OLED display is properly wired to the Arduino
• Double-check the OLED display I2C address: with the OLED connected to the Arduino, upload this code and check the I2C address in the Serial Monitor

You should change the OLED address in the following line, if necessary. In our case, the address is 0x3C.

if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { 

Write Text ' OLED Display

The Adafruit library for the OLED display comes with several functions to write text. In this section, you'll learn how to write and scroll text using the library functions.

'Hello, world!' OLED Display

The following sketch displays Hello, world! message in the OLED display.

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD display connected to I2C (SDA, SCL pins)
Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin();

  if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD allocation failed"));
    for(;;);
  }
  delay();
  display.clearDisplay();

  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 10);
  // Display static text
  display.println("Hello, world!");
  display.display(); 
}

void loop() {
  
}

View raw code

After uploading the code, this is what you'll get in your OLED:

Let's take a quick look on how the code works.

Importing libraries

First, you need to import the necessary libraries. The Wire library to use I2C and the Adafruit libraries to write to the display: Adafruit_GFX and Adafruit_SSD.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>

Initialize the OLED display

Then, you define your OLED width and height. In this example, we're using a 128×64 OLED display. If you're using other sizes, you can change that in the SCREEN_WIDTH, and SCREEN_HEIGHT variables.

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

Then, initialize a display object with the width and height defined earlier with I2C communication protocol (&Wire).

Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

The (-1) parameter means that your OLED display doesn't have a RESET pin. If your OLED display does have a RESET pin, it should be connected to a GPIO. In that case, you should pass the GPIO number as a parameter.

In the setup(), initialize the Serial Monitor at a baud raute of for debugging purposes.

Serial.begin();

Initialize the OLED display with the begin() method as follows:

if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { 
  Serial.println("SSD allocation failed");
  for(;;); // Don't proceed, loop forever
}

This snippet also prints a message on the Serial Monitor, in case we're not able to connect to the display.

Serial.println("SSD allocation failed");

In case you're using a different OLED display, you may need to change the OLED address. In our case, the address is 0x3C.

if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { 

If this address doesn't work, you can run an I2C scanner sketch to find your OLED address. You can find the I2C scanner sketch here.

After initializing the display, add a two second delay, so that the OLED has enough time to initialize before writing text:

delay();

Clear display, set font size, color and write text

After initializing the display, clear the display buffer with the clearDisplay() method:

display.clearDisplay();

Before writing text, you need to set the text size, color and where the text will be displayed in the OLED.

Set the font size using the setTextSize() method:

display.setTextSize(1);             

Set the font color with the setTextColor() method:

display.setTextColor(WHITE);        

WHITE sets white font and black background.

Define the position where the text starts using the setCursor(x,y) method. In this case, we're setting the text to start at the (0,10) coordinates.

display.setCursor(0,10);             

Finally, you can send the text to the display using the println() method, as follows:

display.println("Hello, world!");

Then, you need to call the display() method to actually display the text on the screen.

display.display();

Scrolling Text

The Adafruit OLED library provides useful methods to easily scroll text.

• startscrollright(0x00, 0x0F): scroll text from left to right

• startscrollleft(0x00, 0x0F): scroll text from right to left

• startscrolldiagright(0x00, 0x07): scroll text from left bottom corner to right upper corner

• startscrolldiagleft(0x00, 0x07): scroll text from right bottom corner to left upper corner

The following sketch implements those methods.

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD display connected to I2C (SDA, SCL pins)
Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin();

  if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD allocation failed"));
    for(;;);
  }
  delay();
  display.clearDisplay();

  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  // Display static text
  display.println("Scrolling Hello");
  display.display(); 
  delay(100);
 
}

void loop() {
  // Scroll in various directions, pausing in-between:
  display.startscrollright(0x00, 0x0F);
  delay();
  display.stopscroll();
  delay();
  display.startscrollleft(0x00, 0x0F);
  delay();
  display.stopscroll();
  delay();
  display.startscrolldiagright(0x00, 0x07);
  delay();
  display.startscrolldiagleft(0x00, 0x07);
  delay();
  display.stopscroll();
  delay();
}

View raw code

The text scrolls as shown in the following short video.

Using Other Fonts ' OLED Display

The Adafruit GFX library allows us to use some alternate fonts besides the built-in fonts. It allows you to chose between Serif, Sans, and Mono. Each font is available in bold, italic and in different sizes.

The sizes are set by the actual font. So, the setTextSize() method doesn't work with these fonts. The fonts are available in 9, 12, 18 and 24 point sizes and also contain 7-bit characters (ASCII codes) (described as 7b in the font name).

You can chose from the next selection of fonts:

FreeMono12pt7b.h		FreeSansBoldOblique12pt7b.h
FreeMono18pt7b.h		FreeSansBoldOblique18pt7b.h
FreeMono24pt7b.h		FreeSansBoldOblique24pt7b.h
FreeMono9pt7b.h			FreeSansBoldOblique9pt7b.h
FreeMonoBold12pt7b.h		FreeSansOblique12pt7b.h
FreeMonoBold18pt7b.h		FreeSansOblique18pt7b.h
FreeMonoBold24pt7b.h		FreeSansOblique24pt7b.h
FreeMonoBold9pt7b.h		FreeSansOblique9pt7b.h
FreeMonoBoldOblique12pt7b.h	FreeSerif12pt7b.h
FreeMonoBoldOblique18pt7b.h	FreeSerif18pt7b.h
FreeMonoBoldOblique24pt7b.h	FreeSerif24pt7b.h
FreeMonoBoldOblique9pt7b.h	FreeSerif9pt7b.h
FreeMonoOblique12pt7b.h		FreeSerifBold12pt7b.h
FreeMonoOblique18pt7b.h		FreeSerifBold18pt7b.h
FreeMonoOblique24pt7b.h		FreeSerifBold24pt7b.h
FreeMonoOblique9pt7b.h		FreeSerifBold9pt7b.h
FreeSans12pt7b.h		FreeSerifBoldItalic12pt7b.h
FreeSans18pt7b.h		FreeSerifBoldItalic18pt7b.h
FreeSans24pt7b.h		FreeSerifBoldItalic24pt7b.h
FreeSans9pt7b.h			FreeSerifBoldItalic9pt7b.h
FreeSansBold12pt7b.h		FreeSerifItalic12pt7b.h
FreeSansBold18pt7b.h		FreeSerifItalic18pt7b.h
FreeSansBold24pt7b.h		FreeSerifItalic24pt7b.h
FreeSansBold9pt7b.h		FreeSerifItalic9pt7b.h

The fonts that work better with the OLED display are the 9 and 12 points size.

To use one of those fonts, first you need to include it in your sketch, for example:

#include <Fonts/FreeSerif12pt7b.h>

Next, you just need to use the setFont() method and pass as argument, the specified font:

display.setFont(&FreeSerif12pt7b);

After specifying the font, all methods to write text will use that font. To get back to use the original font, you just need to call the setFont() method with no arguments:

display.setFont();

Upload the next sketch to your board:

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>
#include <Fonts/FreeSerif9pt7b.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD display connected to I2C (SDA, SCL pins)
Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin();

  if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { 
    Serial.println("SSD allocation failed");
    for(;;);
  }
  delay();

  display.setFont(&FreeSerif9pt7b);
  display.clearDisplay();
  display.setTextSize(1);             
  display.setTextColor(WHITE);        
  display.setCursor(0,20);             
  display.println("Hello, world!");
  display.display();
  delay(); 
}
void loop() {
  
}

View raw code

Now, your display prints the 'Hello, world!' message in FreeSerif font.

Draw Shapes in the OLED Display

The Adafruit OLED library provides useful methods to draw pixels, lines and shapes. Let's take a quick look at those methods.

Draw a pixel

To draw a pixel in the OLED display, you can use the drawPixel(x, y, color) method that accepts as arguments the x and y coordinates where the pixel appears, and color. For example:

display.drawPixel(64, 32, WHITE);

Draw a line

Use the drawLine(x1, y1, x2, y2, color) method to create a line. The (x1, y1) coordinates indicate the start of the line, and the (x2, y2) coordinates indicates where the line ends. For example:

display.drawLine(0, 0, 127, 20, WHITE);

Draw a rectangle

The drawRect(x, y, width, height, color) provides an easy way to draw a rectangle. The (x, y) coordinates indicate the top left corner of the rectangle. Then, you need to specify the width, height and color:

display.drawRect(10, 10, 50, 30, WHITE);

You can use the fillRect(x, y, width, height, color) to draw a filled rectangle. This method accepts the same arguments as drawRect().

The library also provides methods to displays rectangles with round corners: drawRoundRect() and fillRoundRect(). These methods accepts the same arguments as previous methods plus the radius of the corner. For example:

display.drawRoundRect(10, 10, 30, 50, 2, WHITE);

Or a filled round rectangle:

display.fillRoundRect(10, 10, 30, 50, 2, WHITE);

Draw a circle

To draw a circle use the drawCircle(x, y, radius, color) method. The (x,y) coordinates indicate the center of the circle. You should also pass the radius as an argument. For example:

display.drawCircle(64, 32, 10, WHITE);

In the same way, to build a filled circle, use the fillCircle() method with the same arguments:

display.fillCircle(64, 32, 10, WHITE);

Draw a triangle

Use the the drawTriangle(x1, y1, x2, y2, x3, y3, color) method to build a triangle. This method accepts as arguments the coordinates of each corner and the color.

If you want to learn more, please visit our website 0 42 inch pm oled display.

display.drawTriangle(10, 10, 55, 20, 5, 40, WHITE);

Use the fillTriangle() method to draw a filled triangle.

display.fillTriangle(10, 10, 55, 20, 5, 40, WHITE);

Invert

The library provides an additional method that you can use with shapes or text: the invertDisplay() method. Pass true as argument to invert the colors of the screen or false to get back to the original colors.

If you call the following command after defining the triangle:

display.invertDisplay(true);

You'll get an inverted triangle as follows:

Code ' Draw Shapes

Upload the following sketch that implements each snippet of code we've covered previously and goes through all the shapes.

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

// Declaration for an SSD display connected to I2C (SDA, SCL pins)
Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin();

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

  // Clear the buffer
  display.clearDisplay();

  // Draw a single pixel in white
  display.drawPixel(64, 32, WHITE);
  display.display();
  delay();

  // Draw line
  display.clearDisplay();
  display.drawLine(0, 0, 127, 20, WHITE);
  display.display();
  delay();
  
  // Draw rectangle
  display.clearDisplay();
  display.drawRect(30, 10, 50, 30, WHITE);
  display.display();
  delay();
  // Fill rectangle
  display.fillRect(30, 10, 50, 30, WHITE);
  display.display();
  delay();

  // Draw round rectangle
  display.clearDisplay();
  display.drawRoundRect(10, 10, 30, 50, 2, WHITE);
  display.display();
  delay();
  // Fill round rectangle
  display.clearDisplay();
  display.fillRoundRect(10, 10, 30, 50, 2, WHITE);
  display.display();
  delay();
  
  // Draw circle
  display.clearDisplay();
  display.drawCircle(64, 32, 10, WHITE);
  display.display();
  delay();
  // Fill circle
  display.fillCircle(64, 32, 10, WHITE);
  display.display();
  delay();
  
  // Draw triangle
  display.clearDisplay();
  display.drawTriangle(10, 10, 55, 20, 5, 40, WHITE);
  display.display();
  delay();
  // Fill triangle
  display.fillTriangle(10, 10, 55, 20, 5, 40, WHITE);
  display.display();
  delay();

  // Invert and restore display, pausing in-between
  display.invertDisplay(true);
  delay();
  display.invertDisplay(false);
  delay();
}

void loop() {
  
}

View raw code

Display Bitmap Images in the OLED

You can display 128×64 bitmap monocolor images on the OLED display.

First, use an imaging program to resize a photo or picture and save it as monochrome bitmap. If you're on a Windows PC, you can use Paint.

Then, use a Image to C Array converter to convert the image into an array. I've used LCD Image Converter.

Run the program and start with a new image. Go to Image > Import and select the bitmap image you've created earlier.

Go to Options > Conversion and in the Prepare tab, select the following options:

• Type: Monochrome, Threshold Dither
• Main Scan Direction: Top to Bottom
• Line Scan Direction: Forward

Go to the Image tab and select the following options:

• Split to rows
• Block size: 8 bit
• Byte order: Little-Endian

Then, click OK. Finally, in the main menu, go to File > Convert. A new file with .c extension should be saved. That file contains the C array for the image. Open that file with a text editor, and copy the array.

In our case, this is the array that we get:

static const uint8_t image_data_Saraarray[] = {
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x0a, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x14, 0x9e, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x36, 0x3f, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x6d, 0xff, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0xfb, 0xff, 0x80, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x03, 0xd7, 0xff, 0x80, 0x0f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x07, 0xef, 0xff, 0x80, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x0f, 0xdf, 0xff, 0x90, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x0f, 0xbf, 0xff, 0xd0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x1d, 0x7f, 0xff, 0xd0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x01, 0x1b, 0xff, 0xff, 0xc0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x02, 0xa7, 0xff, 0xff, 0xc0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x03, 0xff, 0xc0, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0xff, 0x80, 0x00, 0x0b, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x03, 0xff, 0xff, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x07, 0xff, 0xff, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x0f, 0x07, 0xff, 0xf8, 0xf8, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x0e, 0x01, 0xff, 0xc0, 0x38, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x1c, 0x46, 0xff, 0xb1, 0x18, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0x97, 0xff, 0xc0, 0x7a, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xfe, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xfe, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x01, 0x3f, 0xff, 0xff, 0xff, 0xfe, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x01, 0xbf, 0xff, 0xff, 0xff, 0xfe, 0x81, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0xbf, 0xff, 0xff, 0xff, 0xfc, 0x81, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0xff, 0xff, 0xfe, 0xff, 0xfd, 0x83, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0xbf, 0xff, 0xfe, 0xff, 0xfd, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xfb, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x3f, 0xff, 0xdc, 0xff, 0xfa, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xd8, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xf8, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xd0, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xf8, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x90, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xf8, 0x02, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xb0, 0x00, 0x0f, 0xf5, 0xff, 0xd7, 0xf8, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xb0, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x5f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xa0, 0x00, 0x0f, 0xfb, 0xff, 0xff, 0xf0, 0x00, 0x3f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x0f, 0xfd, 0xff, 0xdf, 0xf0, 0x00, 0x3f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x07, 0xff, 0xff, 0xbf, 0xf0, 0x00, 0x0f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x07, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x87, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x03, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x43, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x60, 0x00, 0x01, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x73, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfe, 0xe0, 0x00, 0x00, 0xff, 0xff, 0xff, 0x80, 0x00, 0x7b, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfd, 0xe0, 0x00, 0x00, 0x7f, 0xff, 0xfe, 0x00, 0x00, 0x33, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfd, 0xe0, 0x00, 0x00, 0x3f, 0xff, 0xf8, 0x00, 0x00, 0x27, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0x0f, 0xff, 0xf0, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x60, 0x00, 0x00, 0x67, 0xff, 0xe0, 0x00, 0x00, 0x1b, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfd, 0x40, 0x00, 0x00, 0xf3, 0xff, 0xc4, 0x00, 0x00, 0x0b, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfe, 0x80, 0x00, 0x00, 0xfc, 0xff, 0x8c, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x00, 0x7f, 0x3c, 0x3c, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x3f, 0xc0, 0x7c, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xfc, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff
};

View raw code

Copy your array to the sketch. Then, to display the array, use the drawBitmap() method that accepts the following arguments (x, y, image array, image width, image height, rotation). The (x, y) coordinates define where the image starts to be displayed.

Copy the code below to display your bitmap image in the OLED.

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

static const unsigned char PROGMEM image_data_Saraarray[] = {
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x0a, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x14, 0x9e, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x36, 0x3f, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x6d, 0xff, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0xfb, 0xff, 0x80, 0x1f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x03, 0xd7, 0xff, 0x80, 0x0f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x07, 0xef, 0xff, 0x80, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x0f, 0xdf, 0xff, 0x90, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x0f, 0xbf, 0xff, 0xd0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x1d, 0x7f, 0xff, 0xd0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x01, 0x1b, 0xff, 0xff, 0xc0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x02, 0xa7, 0xff, 0xff, 0xc0, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x03, 0xff, 0xc0, 0x00, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0xff, 0x80, 0x00, 0x0b, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x03, 0xff, 0xff, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0x07, 0xff, 0xff, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x0f, 0x07, 0xff, 0xf8, 0xf8, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x0e, 0x01, 0xff, 0xc0, 0x38, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x1c, 0x46, 0xff, 0xb1, 0x18, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0x97, 0xff, 0xc0, 0x7a, 0x07, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xfe, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x3f, 0xff, 0xff, 0xff, 0xfe, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x01, 0x3f, 0xff, 0xff, 0xff, 0xfe, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfe, 0x01, 0xbf, 0xff, 0xff, 0xff, 0xfe, 0x81, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0xbf, 0xff, 0xff, 0xff, 0xfc, 0x81, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xfc, 0x00, 0xff, 0xff, 0xfe, 0xff, 0xfd, 0x83, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0xbf, 0xff, 0xfe, 0xff, 0xfd, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xfb, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x3f, 0xff, 0xdc, 0xff, 0xfa, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xd8, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xf8, 0x03, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xd0, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xf8, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x90, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xf8, 0x02, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xb0, 0x00, 0x0f, 0xf5, 0xff, 0xd7, 0xf8, 0x01, 0xff, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xb0, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x5f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xa0, 0x00, 0x0f, 0xfb, 0xff, 0xff, 0xf0, 0x00, 0x3f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x0f, 0xfd, 0xff, 0xdf, 0xf0, 0x00, 0x3f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x07, 0xff, 0xff, 0xbf, 0xf0, 0x00, 0x0f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x07, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x87, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x03, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x43, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x60, 0x00, 0x01, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x73, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfe, 0xe0, 0x00, 0x00, 0xff, 0xff, 0xff, 0x80, 0x00, 0x7b, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfd, 0xe0, 0x00, 0x00, 0x7f, 0xff, 0xfe, 0x00, 0x00, 0x33, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfd, 0xe0, 0x00, 0x00, 0x3f, 0xff, 0xf8, 0x00, 0x00, 0x27, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0x0f, 0xff, 0xf0, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x60, 0x00, 0x00, 0x67, 0xff, 0xe0, 0x00, 0x00, 0x1b, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfd, 0x40, 0x00, 0x00, 0xf3, 0xff, 0xc4, 0x00, 0x00, 0x0b, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfe, 0x80, 0x00, 0x00, 0xfc, 0xff, 0x8c, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x00, 0x7f, 0x3c, 0x3c, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x3f, 0xc0, 0x7c, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 
    0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xfc, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff
};
 
void setup() {
  Serial.begin();
 
  if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD allocation failed"));
    for(;;);
  }
  delay(); // Pause for 2 seconds
 
  // Clear the buffer.
  display.clearDisplay();
  
  // Draw bitmap on the screen
  display.drawBitmap(0, 0, image_data_Saraarray, 128, 64, 1);
  display.display();
}
 
void loop() {
  
}

View raw code

After uploading the code, this is what we get on the display.

Display Temperature and Humidity in the OLED Display with Arduino

In this section we'll build a project that displays temperature and humidity readings on the OLED display. We'll get temperature and humidity using the DHT11 temperature and humidity sensor. If you're not familiar with the DHT11 sensor, read the following article:

• Complete Guide for DHT11/DHT22 Humidity and Temperature Sensor With Arduino

Parts required

To complete this project you need the following components:

• 0.96 inch OLED display 
• Arduino ' Read Best Arduino Starter Kits
• DHT11 or DHT22 temperature and humidity sensor 
• Breadboard
• 4.7k Ohm resistor (or 10k Ohm resistor)
• Jumper wires

You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

Schematic

Assemble the circuit by following the next schematic diagram.

Note: if you're using a module with a DHT sensor, it normally comes with only three pins. The pins should be labeled so that you know how to wire them. Additionally, many of these modules already come with an internal pull up resistor, so you don't need to add one to the circuit.

Installing Libraries

Before proceeding, make sure you have installed the'adafruit_GFX.h' and the 'adafruit_SSD.h' libraries to control the OLED display.

For this project you also need two aditional libraries to read from the DHT sensor: the DHT library and the Adafruit_Sensor library. Follow the next steps to install those libraries

1. Open your Arduino IDE and go to Sketch > Include Library > Manage Libraries. The Library Manager should open.

2. Search for 'DHT' on the Search box and install the DHT library from Adafruit.

3. After installing the DHT library from Adafruit, type 'Adafruit Unified Sensor' in the search box. Scroll all the way down to find the library and install it.

4. Restart your Arduino IDE.

Code

After installing all the necessary libraries, you can upload the following code.

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>
#include <Adafruit_Sensor.h>
#include <DHT.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD display connected to I2C (SDA, SCL pins)
Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

#define DHTPIN 2     // Digital pin connected to the DHT sensor

// Uncomment the type of sensor in use:
#define DHTTYPE    DHT11     // DHT 11
//#define DHTTYPE    DHT22     // DHT 22 (AM)
//#define DHTTYPE    DHT21     // DHT 21 (AM)

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin();

  dht.begin();

  if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD allocation failed"));
    for(;;);
  }
  delay();
  display.clearDisplay();
  display.setTextColor(WHITE);
}

void loop() {
  delay();

  //read temperature and humidity
  float t = dht.readTemperature();
  float h = dht.readHumidity();
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
  }

  //clear display
  display.clearDisplay();

  // display temperature
  display.setTextSize(1);
  display.setCursor(0,0);
  display.print("Temperature: ");
  display.setTextSize(2);
  display.setCursor(0,10);
  display.print(t);
  display.print(" ");
  display.setTextSize(1);
  display.cp437(true);
  display.write(167);
  display.setTextSize(2);
  display.print("C");
  
  // display humidity
  display.setTextSize(1);
  display.setCursor(0, 35);
  display.print("Humidity: ");
  display.setTextSize(2);
  display.setCursor(0, 45);
  display.print(h);
  display.print(" %"); 
  
  display.display(); 
}

View raw code

How the Code Works

Read this section if you want to learn how the code works. Otherwise, you can skip to the 'Demonstration' section.

Importing libraries

The code starts by including the necessary libraries. The Wire, Adafruit_GFX and Adafruit_SSD are used to interface with the OLED display. The Adafruit_Sensor and the DHT libraries are used to interface with the DHT22 or DHT11 sensors.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD.h>
#include <Adafruit_Sensor.h>
#include <DHT.h>

Create a display object

Then, define your OLED display dimensions. In this case, we're using a 128×64 pixel display.

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

Then, initialize a display object with the width and height defined earlier with I2C communication protocol (&Wire).

Adafruit_SSD display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

The (-1) parameter means that your OLED display doesn't have a RESET pin. If your OLED display does have a RESET pin, it should be connected to a GPIO. In that case, you should pass the GPIO number as a parameter.

Create a DHT object

Then, define the DHT sensor type you're using. If you're using a DHT11 you don't need to change anything on the code. If you're using another sensor, just uncomment the sensor you're using and comment the others.

#define DHTTYPE    DHT11     // DHT 11
//#define DHTTYPE    DHT22     // DHT 22 (AM)
//#define DHTTYPE    DHT21     // DHT 21 (AM)

Initialize a DHT sensor object with the pin and type defined earlier.

DHT dht(DHTPIN, DHTTYPE);

setup()

In the setup(), initialize the serial monitor for debugging purposes.

Serial.begin();

Initialize the DHT sensor:

dht.begin();

Then, initialize the OLED display.

if(!display.begin(SSD_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
  Serial.println(F("SSD allocation failed"));
  for(;;);
}

In this case, the address of the OLED display we're using is 0x3C. If this address doesn't work, you can run an I2C scanner sketch to find your OLED address. You can find the I2C scanner sketch here.

Add a delay to give time for the display to initialize, clear the display and set the text color to white:

delay();
display.clearDisplay();
display.setTextColor(WHITE)

In the loop() is where we read the sensor and display the temperature and humidity on the display.

Get temperature and humidity readings from DHT

The temperature and humidity are saved on the t and h variables, respectively. Reading temperature and humidity is as simple as using the readTemperature() and readHumidity() methods on the dht object.

float t = dht.readTemperature();
float h = dht.readHumidity();

In case we are not able to get the readings, display an error message:

if (isnan(h) || isnan(t)) {
  Serial.println("Failed to read from DHT sensor!");
}

If you get that error message, read our troubleshooting guide: how to fix 'Failed to read from DHT sensor'.

Display sensor readings on the OLED display

The following lines display the temperature on the OLED display.

  display.setTextSize(1);
  display.setCursor(0,0);
  display.print("Temperature: ");
  display.setTextSize(2);
  display.setCursor(0,10);
  display.print(t);
  display.print(" ");
  display.setTextSize(1);
  display.cp437(true);
  display.write(167);
  display.setTextSize(2);
  display.print("C");

We use the setTextSize() method to define the font size, the setCursor() sets where the text should start being displayed and the print() method is used to write something on the display.

To print the temperature and humidity you just need to pass their variables to the print() method as follows:

display.print(t);

The 'Temperature' label is displayed in size 1, and the actual reading is displayed in size 2.

To display the º symbol, we use the Code Page 437 font. For that, you need to set the cp437 to true as follows:

display.cp437(true);

Then, use the write() method to display your chosen character. The º symbol corresponds to character 167.

display.write(167);

A similar approach is used to display the humidity:

display.setTextSize(1);
display.setCursor(0, 35);
display.print("Humidity: ");
display.setTextSize(2);
display.setCursor(0, 45);
display.print(h);
display.print(" %"); 

Don't forget that you need to call display.display() at the end, so that you can actually display something on the OLED.

display.display(); 

Demonstration

After wiring the circuit and uploading the code, the OLED display shows the temperature and humidity readings. The sensor readings are updated every five seconds.

Troubleshooting

If your DHT sensor fails to get the readings or you get the message 'Failed to read from DHT sensor', read our DHT Troubleshooting Guide to help you solve that problem.

If you get the 'SSD allocation failed' error or if the OLED is not displaying anything in the screen, it can be one of the following issues:

Wrong I2C address

The I2C address for the OLED display we are using is 0x3C. However, yours may be different. So, make sure you check your display I2C address using an I2C scanner sketch.

SDA and SCL not connected properly

Please make sure that you have the SDA and SCL pins of the OLED display wired correctly.

Wrapping Up

The OLED display provides an easy and inexpensive way to display text or graphics using an Arduino. We hope you've found this guide and the project example useful.

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• Arduino Mini Course (Free)
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Thanks for reading

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