OLED I2C Display Using Microchip PIC Microcontroller

A few days back, I ordered a cheap OLED Display (based on an SSD1306 controller), for one of my projects, and then for testing purposes, I used it with Arduino as it has lots of Libraries for this display.
Unfortunately, I am not able to find the libraries for Microchip PIC Micro-controller and that's why I decided to port the Arduino Libraries written in C++ to C and make my OLED display work with Microchip PIC Micro-controller.

Connection
This OLED Display comes in two sizes one is 128x64 and another is 128x32, the one shown above is 128x32, apart from this, the interface is either SPI or I2C, the one I am using works on I2C mode and this post will be dedicated to that only.
These displays generally have 4 or 5 pins, and the pin description is written over the pins. The pins are as follows.

Pin Name	Description
VCC	Power Supply Pin, 3.3V or 5V
GND	Power Supply Ground Pin
SCL	I2C Clock Line
SDA	I2C Data Line
RESET	Reset Pin (Optional), if present connect to 3.3V or 5V

I am using PIC18F2550 for this, and the connection diagram is as follow.

Connection Diagram

As I have a 128x32 OLED display, so I will make sure that the same library works on both types of display (128x64 and 128x32). That's why I tested the 128x64 display in Labcenter Electronics Proteus and 128x32 on real hardware with the same library.

Pin Name	Description
VCC	PIC 5V Supply
GND	PIC GND Supply
SCL	RB1 (Pin 22)
SDA	RB0 (Pin 21)
RESET	In Proteus to 5V and on my actual hardware this pin is not present

Software
The software is written in mikroC for PIC compiler and can be used with MPLAB XC8 compiler also without many changes.
To communicate with the device connected to the I2C bus, you must know its address, in our case the address is 0x3D (as per the connection diagram shown above).
When the SSD1306 controller is working in I2C mode, the D/C pin of this controller decides the address, if it is connected with Ground, then the address is 0x3C and if connected with VCC, then its address is 0x3D.
Note:
The OLED Module which I purchased has address 0x3C as the D/C line is connected with the ground.
The following is the test software that displays images, text, lines, rectangle, and circles on this display.

#include "OLED_I2C.h"

void main()
{
  UART1_Init(9600);
  OLED_Init();
  Delay_ms(2000);
  OLED_ClearDisplay();
  OLED_Update();
  Delay_ms(1000);
  OLED_FillDisplay();
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();
  // Draw Single Pixel
  OLED_DrawPixel(10, 10, WHITE);
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();

  // Draw Many Lines
  test_draw_lines();
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();

  // Draw Vertical and Horizontal Lines
  test_draw_v_h_lines();
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();

  // Draw Rectangles
  test_draw_rectangles();
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();

  // Draw Circles
  test_draw_circles();
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();

  // Text
  test_text_display();
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();
  OLED_Update();

  // Image
  while(1)
  {
    test_images();
    OLED_Update();
  }
}

// Function Definitions
void test_draw_lines( void )
{
  uint8_t i;
  for ( i=0; i<OLED_Width(); i+=4)
  {
    OLED_Line(0, 0, i, OLED_Height()-1, WHITE);
    OLED_Update();
  }
  for ( i=0; i<OLED_Height(); i+=4 )
  {
    OLED_Line(0, 0, OLED_Width()-1, i, WHITE);
    OLED_Update();
  }
}
void test_draw_v_h_lines( void )
{
  uint8_t i;
  // Horizontal lines test
  for( i=0; i< OLED_Height(); i+=4 )
  {
   OLED_H_Line(0, OLED_Width()-1, i, WHITE);
   OLED_Update();
  }
  Delay_ms(1000);
  OLED_ClearDisplay();
  OLED_Update();
  // Vertical lines test
  for( i=0; i< OLED_Width(); i+=4 )
  {
    OLED_V_Line(0, OLED_Height()-1, i, WHITE);
    OLED_Update();
  }
}

void test_draw_rectangles( void )
{
  uint8_t i;
  for ( i=0; i<OLED_Height()/2; i+=2)
  {
    OLED_Rectangle(i, i, OLED_Width()-1-i, OLED_Height()-1-i, WHITE);
    OLED_Update();
    Delay_ms(250);
  }
  Delay_ms(1000);
  OLED_ClearDisplay();
  OLED_Update();
  for( i=OLED_Height()/2; i>0; i-- )
  {
    OLED_Rectangle(i,i, OLED_Width()-i, OLED_Height()-i, WHITE );
  }
}

void test_draw_circles( void )
{
  uint8_t i;
  for( i=0; i<OLED_Width()/2; i+=5 )
  {
    OLED_Circle(OLED_Width()/2, OLED_Height()/2, i , WHITE);
    OLED_Update();
  }
}

void test_text_display( void )
{
  OLED_SetFont( SMALL_FONTS );
  OLED_Write_Text(0,0,"ABCDEFGHIJKLMNOPQRSTU");
  OLED_Write_Text(0,8,"VWXYZ0123456789~!@#$%");
  OLED_Update();
  Delay_ms(1000);
  OLED_Write_Text(0,16,"abcdefghijklmnopqrstu");
  OLED_Write_Text(0,24,"vwxyz");
  OLED_Update();
  OLED_ClearDisplay();
  Delay_ms(1000);
  OLED_SetFont( TINY_FONTS );
  OLED_Write_Text(0,0,"ABCDEFGHIJLKLMNOPQRSTUVWXYZ");
  OLED_Write_Text(0,8,"abcdefghijklmnopqrstuvwxyz");
  OLED_Write_Text(0,16,"0123456789");
  OLED_Update();
  Delay_ms(1000);
  OLED_ClearDisplay();
  OLED_Update();
}

void test_images( void )
{
  OLED_Image(bank);
  OLED_Update();
  Delay_ms(1000);
  OLED_InvertDisplay(TRUE);
  OLED_Update();
  Delay_ms(1000);
  OLED_InvertDisplay(FALSE);

  OLED_Image(house);
  OLED_Update();
  Delay_ms(1000);
  OLED_InvertDisplay(TRUE);
  OLED_Update();
  Delay_ms(1000);
  OLED_InvertDisplay(FALSE);
  Delay_ms(1000);
}

The following video shows the output of the above program when flashed on the actual hardware.

The following images are the snapshots taken from the actual OLED Display.

The following are the snapshots taken from the Labcenter Electronics Proteus.

Image Display

Single Pixel Turn-On

Lines Display

Horizontal Lines Display

Vertical Lines Display

Rectangles Display

Circles Display

Small Fonts Display

Tiny Fonts Display

Image Display

Use the following link to download the complete project, and stay tuned to this page for updated version of this library.
Version 1.0: Initial Release
Features:

• For displaying text and numbers only two fonts are supported TINY_FONTS and SMALL_FONTS
• The following functions are added.

void OLED_Init( void );

uint8_t OLED_Width( void );

uint8_t OLED_Height( void );

void OLED_Update( void );

void OLED_SetContrast( uint8_t contrast );

void OLED_ClearDisplay( void );

void OLED_FillDisplay( void );

void OLED_DrawPixel( uint8_t x, uint8_t y, uint8_t color);

void OLED_InvertDisplay( uint8_t value );

void OLED_SetFont( const uint8_t *font);

void OLED_InvertFont( uint8_t invert_status );

void OLED_Circle( int8_t x_center, int8_t y_center, uint8_t radius, uint8_t color);

void OLED_Line( int8_t x_start, int8_t y_start, int8_t x_end, int8_t y_end, uint8_t color);

void OLED_V_Line ( uint8_t y_start, uint8_t y_end, uint8_t x_pos, uint8_t color);

void OLED_H_Line( uint8_t x_start, uint8_t x_end, uint8_t y_pos, uint8_t color);

void OLED_Rectangle( uint8_t x1, uint8_t y1, uint8_t x2, uint8_t y2, uint8_t color);

void OLED_FillRectangle( uint8_t x1, uint8_t y1, uint8_t x2, uint8_t y2, uint8_t color);

void OLED_Triangle(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1, uint8_t x2, uint8_t y2, uint8_t color);

void OLED_Circle( int8_t x0, int8_t y, uint8_t r, uint8_t color );

void OLED_Image( const uint8_t *image);

void OLED_Write( uint8_t x, uint8_t y, uint8_t value );

void OLED_Write_Text(uint8_t x, uint8_t y, uint8_t *text);

Note: Please use the comment box to report bugs and request for new feature support.
2nd Feb 2020: Project Updated on GitHub
Based on the request I received on my YouTube videos and here and over emails, I am hosting this project now on GitHub. Now, this is based on MPLABX and XC8 compilers.
The good thing is that you can report issues there directly.
Download Source From GitHub