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What is an OLED?

An OLED is a type of diode that consists of an organic compound that emits light when current flows through it.

Step 1: How Does an OLED Communicate With Arduino?

The way the OLED communicates with Arduino is via Inter-Integrated Circuit (I2C). However, it is also possible to communicate via Serial Peripheral Interface (SPI).

For the purpose of this tutorial, we are going to focus on I2C communication. This type of communication allows multiple slaves to communicate with a master. In this case, we will only be working with one slave: chip SSD1306. Our master will be Arduino UNO.

SSDI1306 is a single chip CMOS OLED/PLED driver with controller for organic/polymer light emitting diode dot-matrix graphic display system. In other words, it is the device in charge of controlling the screen by telling it what to do. In order to establish I2C communication between master and slave, only two channels are required: SDA and CLK.

However, we also need to take into account VCC and Ground for voltage supply and, in this case, RST for initialization purposes. The picture above shows the wiring setup for our OLED.

Step 2: Establishing Channels for Communication

SDA is in charge of transmitting data and it corresponds to pin A4 in the Arduino.

CLK is in charge of setting the clock pulse for synchronization, and it corresponds to pin A5 in the Arduino.

These pins, however, will change if you are not using Arduino UNO or Ethernet.

Refer to the link below to see I2C pins for different versions of Arduino:

https://www.arduino.cc/en/Reference/Wire

RST is used to reset the device to its default setup and it can be wired to any digital input in the Arduino. In this case, we used pin 10. Once the channels for communication have been established, it is now possible to send information to our device. Figure 1, above, shows how this is done.

Step 3: Establishing Channels for Communication - Continued

The first thing that we need is the slave address. This seven bit number identifies a particular device so that the master knows what slave it needs to communicate with.

From the SSD1306 datasheet, the slave address for this driver can be either “0111100” or “0111101” depending on SA0 (whether it is high or low). Its default value is high, but, if you desire to change the slave address, you can wire SA0 to any digital pin in the Arduino and set it to zero. In this tutorial, we decided not to change SA0, thus, the address of our slave is 0x3D. Since the OLED will always be in write mode, the R/W# bit (read/write bit) is set to “0.”

The next thing that we need is the control byte. This is defined by Co (continuation bit) and D/C# (data/command selection bit), followed by six “0s.” Co determines whether the following byte is going to be a single byte, or a stream of bytes, while D/C# determines if the byte is going to be treated as data or a command. Thus, we end up having four possible control bytes:

  • 0x40: Data stream
  • 0xC0: Single Data Byte
  • 0x80: Single Command byte
  • 0x00: Command Stream

You can find a list of commands in Table 9-1 on the SSD1306 datasheet.

Step 4: How Is Data Displayed?

The OLED consists of 128 columns (SEG) and 8 pages each containing 8 rows (COM) as shown in Figure 2.

Step 5: How Is Data Displayed? - Continued

While commands are used to configure the screen and personalize it through the use of registers, data is used to display whatever information is stored in the GDDRAM (Graphic Display Data RAM). If we write byte 00000001,” the first pixel located on the top left corner, or on page 0 column 0, will be turned on. The reason why the byte is written in reverse order is because the OLED configures the data to display as shown in the image above.

With the use of a pointer, the data starts filling the column from the least significant bit to the most significant bit. Once the pointer reaches the end of the column, it automatically moves to the next column in horizontal addressing mode, or to the next page in vertical addressing mode (refer to SSD1306 datasheet for addressing mode).

Step 6: How to Draw a Pixel?

Now that we know how the OLED works, we can create a program that lets the user turn on a specific pixel on the screen.

#include //Include Wire library for I2C communication
#define HEIGHT 64 #define WIDTH 128 const int RST = 10; //Assign pin 10 for Reset int i; //Set variable i as integer static unsigned char array[1024]; //buffer array/> void setup() { pin_init(); //Initialize pins initialize_OLED(); //Initialize screen memset(array, 0, sizeof(array)); //Clear array draw_pixel(63,31); //Store pixel at (x,y) location Flush(); //Send data } void loop() { //Nothing happens here } void pin_init(){ Serial.begin(9600); //Set baud for serial transmission pinMode(RST, OUTPUT); //Set RST as output } void initialize_OLED(){ Wire.begin(); //Initialize I2C interface digitalWrite(RST, LOW); //Set reset pin low (active) delay(10); //Wait 100 ms digitalWrite(RST, HIGH); //Set reset pin high (inactive) Wire.beginTransmission(0x3D); // Start communication with slave Wire.write(0x00); //Command stream Wire.write(0xAE); //Set display Off Wire.write(0xD5); //Set display clock divide ratio/oscillator frequency Wire.write(0x80); Wire.write(0xA8); //Set multiplex ratio Wire.write(0x3F); Wire.write(0xD3); //Set display offset Wire.write(0x00); Wire.write(0x40); //Set display start line Wire.write(0x8D); //Set charge pump Wire.write(0x14); //VCC generated by internal DC/DC circuit Wire.write(0xA1); //Set segment re-map Wire.write(0xC0); //Set COM output scan direction Wire.write(0xDA); //Set COM pins hardware configuration Wire.write(0x12); Wire.write(0x81); //Set contrast control Wire.write(0xCF); Wire.write(0xD9); //Set pre-changed period Wire.write(0xF1); Wire.write(0xDB); //Set VCOMH Deselected level Wire.write(0x40); Wire.write(0xA4); //Set entire display on/off Wire.write(0xA6); //Set normal display Wire.write(0x20); //Set memory address mode Wire.write(0x00); //Horizontal Wire.write(0xAF); //Set display on Wire.endTransmission(); //End communicaiton with slave } void draw_pixel(int x, int y) if((x<0) || (x>=WIDTH) || (y<0) || (y>=HEIGHT)){ //Check for boundaries return; } else{ array[x+(y/8)*WIDTH] |= _BV((y%8)); //Store pixel in array } } void Flush(){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x00); //Command stream Wire.write(0x00); //Set lower column start address for page addressing mode Wire.write(0x10); //Set higher column start address for page addressing mode Wire.write(0x40); //Set display start line Wire.endTransmission(); //End communication with slave unsigned char twbrbackup = TWBR; //Two wire bit rate register TWBR = 12; //Set to 400 kHz for(unsigned short q=0; q<(WIDTH*HEIGHT/8); q++){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x40); //Data stream for(unsigned char w=0; w<16; w++){ Wire.write(array[q]); //Transmit data to be displayed q++; } q--; Wire.endTransmission(); //End communication with slave } TWBR = twbrbackup; }

The Wire library enables Arduino to communicate with I2C devices. In the first part of the code we assign the already mentioned digital pin to RST, and create an array to buffer the data that we want to display. Then pin RST is initialized by making it an output. Next, the OLED is initialized by following the example shown on the display datasheet on page 15. It is recommended that you reset the device once before you start using it. This is done by setting RST low for some time and then high. Since this pin is active low, it needs to be high during normal operation.

Step 7: How to Draw a Pixel? - Continued

The function “pixel” is then created to store the pixel in a specific location in the array buffer. This function takes two arguments, x and y, to give the program an exact coordinate of where we want the pixel. X can adopt any value between 0-127, while y can have any value between 0-63. Coordinate (0,0) would be located in the bottom left side of our screen. If the coordinate is out of range, then the program won’t display anything.

Finally, the function “Flush” is used to display the elements of the array buffer by sending the information in 16 byte burst transfers as the program travels through the whole buffer. Inside this function, TWBR (Two wire bit rate register) is set to 12in order to upgrade the frequency of the Arduino clock (SCL) from 100kHz to 400kHz. This way data transmission is faster. Below is shown how 12 was calculated in the formula above.

Where:
CPUFrequency = 16MHz

TWIFrequency = 400kHz

TWI = Two Wire Interface

Step 8: How to Draw a Pixel? - Continued

For this tutorial, we chose coordinate (63,31) to turn on the pixel located at the middle of the screen as shown in the picture above.

Step 9: How to Draw a Line?

Once we have a pixel function, we can use it to draw a line defined by a start and end point on the x and y axis on the screen.

#include //Include Wire library for I2C communication
#define HEIGHT 64 #define WIDTH 128 const int RST = 10; //Assign pin 10 for Reset int i; //Set variable i as integer static unsigned char array[1024]; //Buffer array void setup() { pin_init(); //Initialize pins initialize_OLED(); //Initialize screen memset(array, 0, sizeof(array)); //Initialize array with 0s line(0,63,0,31); //Draw line Flush(); //Send data } void loop() { } void pin_init(){ Serial.begin(9600); //Set baud for serial transmission pinMode(RST, OUTPUT); //Set RST as output } void initialize_OLED(){ Wire.begin(); //Initialize I2C interface digitalWrite(RST, LOW); //Set RST pin low delay(100); //Wait 100 ms digitalWrite(RST, HIGH); //Set RST pin high Wire.beginTransmission(0x3D); // Start communication with slave Wire.write(0x00); //Command stream Wire.write(0xAE); //Set display Off Wire.write(0xD5); //Set display clock divide ratio/oscillator frequency Wire.write(0x80); Wire.write(0xA8); //Set multiplex ratio Wire.write(0x3F); Wire.write(0xD3); //Set display offset Wire.write(0x00); Wire.write(0x40); //Set display start line Wire.write(0x8D); //Set charge pump Wire.write(0x14); //VCC generated by internal DC/DC circuit Wire.write(0xA1); //Set segment re-map Wire.write(0xC0); //Set COM output scan direction Wire.write(0xDA); //Set COM pins hardware configuration Wire.write(0x12); Wire.write(0x81); //Set contrast control Wire.write(0xCF); Wire.write(0xD9); //Set pre-changed period Wire.write(0xF1); Wire.write(0xDB); //Set VCOMH Deselected level Wire.write(0x40); Wire.write(0xA4); //Set entire display on/off Wire.write(0xA6); //Set normal/inverse display Wire.write(0x20); //Set memory address mode Wire.write(0x00); //Horizontal Wire.write(0xAF); //Set display on Wire.endTransmission(); //End communicaiton with slave } /*Bresenham's line drawing algorithm*/ void line(int x1, int x2, int y1, int y2){ int cx = x1; int cy = y1; int dx = x2-cx; int dy = y2-cy; if(dx<0){ dx = 0-dx; } if(dy<0){ dy = 0-dy; } int sx = 0; int sy = 0; if(cx(0-dy)){ err = err-dy; cx = cx+sx; } if(e2=WIDTH) || (y<0) || (y>=HEIGHT)){ //Check for boundaries return; } else{ array[x+(y/8)*WIDTH] |= _BV((y%8)); //Store pixel in array } } void Flush(){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x00); //Command stream Wire.write(0x00); //Set lower column start address for page addressing mode Wire.write(0x10); //Set higher column start address for page addressing mode Wire.write(0x40); //Set display start line Wire.endTransmission(); //End communication with slave unsigned char twbrbackup = TWBR; //Two wire bit rate register TWBR = 12; //Set to 400 kHz for(unsigned short q=0; q<(WIDTH*HEIGHT/8); q++){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x40); //Data stream for(unsigned char w=0; w<16; w++){ Wire.write(array[q]); //Transmit data to be displayed q++; } q--; Wire.endTransmission(); //End communication with slave } TWBR = twbrbackup; }

The line function is based on the Bresenham's Line Drawing Algorithm used to draw lines with pixels. The following pseudo code was used to implement the algorithm in our program:
http://41j.com/blog/2012/09/bresenhams-line-drawin...

This algorithm basically fills in the pixels between (x0,y0) and (x1,y1) by deciding what pixels should be turned on next based on an error value. Refer to the following links for more information on the algorithm:
http://www.cs.helsinki.fi/group/goa/mallinnus/line...
https://en.wikipedia.org/wiki/Bresenham%27s_line_a...

Step 10: How to Draw a Line? - Continued

The pixel function is used to store a pixel of the line in the array buffer at a specific location each time it is called in the program. This way the array buffer is filled with all the pixels required to draw our line. Once the buffer is loaded with the necessary elements, the Flush function is used to display the data in the screen. By giving our line function four arguments (start and end points on the x and y axis), we can now draw a line like the one shown above.

In this example, the line goes from (0,0) to (63,31). In other words, it goes from the bottom left corner to the center of our screen.

Step 11: How to Draw a Square?

We can use the following code to draw a square on our screen:

#include //Include Wire library for I2C communication
#define HEIGHT 64 #define WIDTH 128 const int RST = 10; //Assign pin 10 for Reset int i; //Set variable i as integer static unsigned char array[1024]; //Buffer array void setup() { pin_init(); //Initialize pins initialize_OLED(); //Initialize screen memset(array, 0, sizeof(array)); //Initialize array with 0s square(117,127,53,63); //Draw square Flush(); //Send data } void loop() { } void pin_init(){ Serial.begin(9600); //Set baud for serial transmission pinMode(RST, OUTPUT); //Set RST as output } void initialize_OLED(){ Wire.begin(); //Initialize I2C interface digitalWrite(RST, LOW); //Set RST pin low delay(100); //Wait 100 ms digitalWrite(RST, HIGH); //Set RST pin high Wire.beginTransmission(0x3D); // Start communication with slave Wire.write(0x00); //Command stream Wire.write(0xAE); //Set display Off Wire.write(0xD5); //Set display clock divide ratio/oscillator frequency Wire.write(0x80); Wire.write(0xA8); //Set multiplex ratio Wire.write(0x3F); Wire.write(0xD3); //Set display offset Wire.write(0x00); Wire.write(0x40); //Set display start line Wire.write(0x8D); //Set charge pump Wire.write(0x14); //VCC generated by internal DC/DC circuit Wire.write(0xA1); //Set segment re-map Wire.write(0xC0); //Set COM output scan direction Wire.write(0xDA); //Set COM pins hardware configuration Wire.write(0x12); Wire.write(0x81); //Set contrast control Wire.write(0xCF); Wire.write(0xD9); //Set pre-changed period Wire.write(0xF1); Wire.write(0xDB); //Set VCOMH Deselected level Wire.write(0x40); Wire.write(0xA4); //Set entire display on/off Wire.write(0xA6); //Set normal/inverse display Wire.write(0x20); //Set memory address mode Wire.write(0x00); //Horizontal Wire.write(0xAF); //Set display on Wire.endTransmission(); //End communication with slave } /*Function to draw square*/ void square(int x1, int x2, int y1, int y2){ int x, y; //Define x and y as integer variables Wire.beginTransmission(0x3D); //Start communication with slave for(x=x1; x=WIDTH) || (y<0) || (y>=HEIGHT)){ //Check for boundaries return; } else{ array[x+(y/8)*WIDTH] |= _BV((y%8)); //Store pixel in array } } void Flush(){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x00); //Command stream Wire.write(0x00); //Set lower column start address for page addressing mode Wire.write(0x10); //Set higher column start address for page addressing mode Wire.write(0x40); //Set display start line Wire.endTransmission(); //End communication with slave unsigned char twbrbackup = TWBR; //Two wire bit rate register TWBR = 12; //Set to 400 kHz for(unsigned short q=0; q<(WIDTH*HEIGHT/8); q++){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x40); //Data stream for(unsigned char w=0; w<16; w++){ Wire.write(array[q]); //Transmit data to be displayed q++; } q--; Wire.endTransmission(); //End communication with slave } TWBR = twbrbackup; }

The square function takes four arguments, a start and end point on the x and y axis, to define the height and width of our rectangle. Then four lines are drawn independently using, once again, the pixel function.

The first line to be drawn is the bottom line of our square from x1-x2 on the y1 axis. The second line to be drawn is the upper line of our square from x1-x2 on the y2 axis. The third line to be drawn is the left side of our square from y1-y2 on the x1 axis. The last line to be drawn is the right side of our square from y1-y2 on the x2 axis. Once all the lines’ pixels have been stored in the array, the Flush function is used to display the four lines. Above is the picture of a 10 x 10 pixels square located at the top right corner of our screen.

Step 12: How to Draw a Circle?

We can use the following code to generate a circle on our screen:

#include //Include Wire library for I2C communication
#define HEIGHT 64 #define WIDTH 128 const int RST = 10; //Assign pin 10 for Reset int i; //Set variable i as integer static unsigned char array[1024]; //Buffer array void setup() { pin_init(); //Initialize pins initialize_OLED(); //Initialize screen memset(array, 0, sizeof(array)); //Initialize array with 0s circle(63,31,10); //Draw circle, (x,y,R) Flush(); //Send data } void loop() { } void pin_init(){ Serial.begin(9600); //Set baud for serial transmission pinMode(RST, OUTPUT); //Set RST as output } void initialize_OLED(){ Wire.begin(); //Initialize I2C interface digitalWrite(RST, LOW); //Set RST pin low delay(100); //Wait 100 ms digitalWrite(RST, HIGH); //Set RST pin high Wire.beginTransmission(0x3D); // Start communication with slave Wire.write(0x00); //Command stream Wire.write(0xAE); //Set display Off Wire.write(0xD5); //Set display clock divide ratio/oscillator frequency Wire.write(0x80); Wire.write(0xA8); //Set multiplex ratio Wire.write(0x3F); Wire.write(0xD3); //Set display offset Wire.write(0x00); Wire.write(0x40); //Set display start line Wire.write(0x8D); //Set charge pump Wire.write(0x14); //VCC generated by internal DC/DC circuit Wire.write(0xA1); //Set segment re-map Wire.write(0xC0); //Set COM output scan direction Wire.write(0xDA); //Set COM pins hardware configuration Wire.write(0x12); Wire.write(0x81); //Set contrast control Wire.write(0xCF); Wire.write(0xD9); //Set pre-changed period Wire.write(0xF1); Wire.write(0xDB); //Set VCOMH Deselected level Wire.write(0x40); Wire.write(0xA4); //Set entire display on/off Wire.write(0xA6); //Set normal/inverse display Wire.write(0x20); //Set memory address mode Wire.write(0x00); //Horizontal Wire.write(0xAF); //Set display on Wire.endTransmission(); //End communication with slave } /*Midpoint circle algorithm*/ void circle(int x0, int y0, int R){ int x = R; //Set x equal to radius int y = 0; int de = 1-x; while(x>=y){ draw_pixel(x+x0, y+y0); //First octant draw_pixel(y+x0, x+y0); //Second octant draw_pixel(-y+x0, x+y0); //Third octant draw_pixel(-x+x0, y+y0); //Fourth octant draw_pixel(-x+x0, -y+y0); //Fifth octant draw_pixel(-y+x0, -x+y0); //Sixth octant draw_pixel(y+x0, -x+y0); //Seventh octant draw_pixel(x+x0, -y+y0); //Eight octant y++; if(de<=0){ de += 2*y+1; } else{ x--; de += 2*(y-x)+1; } } } void draw_pixel(int x, int y){ if((x<0) || (x>=WIDTH) || (y<0) || (y>=HEIGHT)){ //Check for boundaries return; } else{ array[x+(y/8)*WIDTH] |= _BV((y%8)); //Store pixel in array } } void Flush(){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x00); //Command stream Wire.write(0x00); //Set lower column start address for page addressing mode Wire.write(0x10); //Set higher column start address for page addressing mode Wire.write(0x40); //Set display start line Wire.endTransmission(); //End communication with slave unsigned char twbrbackup = TWBR; //Two wire bit rate register TWBR = 12; //Set to 400kHz for(unsigned short q=0; q<(WIDTH*HEIGHT/8); q++){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x40); //Data stream for(unsigned char w=0; w<16; w++){ Wire.write(array[q]); //Transmit data to be displayed q++; } q--; Wire.endTransmission(); //End communication with slave } TWBR = twbrbackup; }

The circle function is based on the Midpoint Circle Algorithm used to generate circles with pixels. The algorithm draws one pixel at a time in each octant of the circle by means of symmetry until the circumference is completed. Once more, the pixel function is used to draw each pixel of the circle every time it is called in the program. Refer to the following link for more information on the algorithm:

https://en.wikipedia.org/wiki/Midpoint_circle_algo...

By giving our circle function three arguments (origin at (x,y) and radius), we can now draw a circle like the one above.

In this example the circle’s origin is at (63,31) and has a radius of 10, thus generating a circle at the center of the page with a radius of 10 pixels.

Step 13: Displaying Any Image

If we use a buffered display with defined values, we can display any image we want on our screen. The following code shows how this is done:

#include //Include Wire library for I2C communication
const int RST = 10; //Assign pin 10 for Reset int i; //Set variable i as integer const unsigned char js[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0x80, 0xC0, 0xC0, 0xC0, 0xC0, 0xC0, 0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 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0xA4, 0x58, 0xA0, 0x58, 0x04, 0x00, 0x54, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x84, 0x00, 0x60, 0x2A, 0x90, 0x64, 0x58, 0xA4, 0x58, 0x24, 0x98, 0x68, 0xA8, 0x54, 0x68, 0x24, 0x24, 0x58, 0xA4, 0x58, 0xA4, 0x48, 0x94, 0x68, 0x90, 0x6A, 0xD4, 0x28, 0x20, 0xD4, 0x68, 0x12, 0x50, 0xA4, 0x48, 0xB4, 0xA4, 0x18, 0x50, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x25, 0x7E, 0x9A, 0xE5, 0x76, 0x59, 0xCA, 0xB5, 0x9D, 0x6A, 0xFD, 0x92, 0xDA, 0x61, 0x60, 0xA0, 0x80, 0xC0, 0x20, 0xC0, 0x40, 0xA0, 0x80, 0xE0, 0x40, 0xC0, 0x40, 0xA0, 0x80, 0xC0, 0x20, 0xC0, 0x40, 0xA0, 0x80, 0xE0, 0x40, 0xC0, 0x40, 0xA0, 0x80, 0xC0, 0x20, 0xC0, 0x40, 0xC0, 0x80, 0x60, 0xC0, 0xA0, 0x80, 0xC0, 0xC0, 0x6D, 0x6F, 0xDF, 0xBF, 0xAF, 0x7F, 0xCF, 0xBF, 0xBF, 0xDF, 0x6F, 0x7F, 0xDF, 0x9F, 0xAF, 0xC0, 0x40, 0x80, 0xA0, 0xC0, 0x40, 0x40, 0xC0, 0xC0, 0x40, 0x40, 0xC0, 0xC0, 0x80, 0xE0, 0x40, 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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; void setup() { pin_init(); //Initialize pins initialize_OLED(); //Initialize screen pattern(); //Display image } void loop() { } void pin_init(){ Serial.begin(9600); //Set baud for serial transmission pinMode(RST, OUTPUT); //Set RST as output } void initialize_OLED(){ Wire.begin(); //Initialize I2C interface digitalWrite(RST, LOW); //Set RST pin low delay(100); //Wait 100 ms digitalWrite(RST, HIGH); //Set RST pin high Wire.beginTransmission(0x3D); // Start communication with slave Wire.write(0x00); //Command stream Wire.write(0xAE); //Set display Off Wire.write(0xD5); //Set display clock divide ratio/oscillator frequency Wire.write(0x80); Wire.write(0xA8); //Set multiplex ratio Wire.write(0x3F); Wire.write(0xD3); //Set display offset Wire.write(0x00); Wire.write(0x40); //Set display start line Wire.write(0x8D); //Set charge pump Wire.write(0x14); //VCC generated by internal DC/DC circuit Wire.write(0xA1); //Set segment re-map Wire.write(0xC8); //Set COM output scan direction Wire.write(0xDA); //Set COM pins hardware configuration Wire.write(0x12); Wire.write(0x81); //Set contrast control Wire.write(0xCF); Wire.write(0xD9); //Set pre-changed period Wire.write(0xF1); Wire.write(0xDB); //Set VCOMH Deselected level Wire.write(0x40); Wire.write(0xA4); //Set entire display on/off Wire.write(0xA6); //Set normal/inverse display Wire.write(0x20); //Set memory address mode Wire.write(0x00); //Vertical Wire.write(0xAF); //Set display on Wire.endTransmission(); //End communication with slave } void pattern(){ for(i=0; i<1024; i++){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x40); //Data stream for(unsigned char x=0; x<16; x++){ Wire.write(js[i]); //Transmit data to be displayed i++; } i--; Wire.endTransmission(); //End communication with slave } }

Step 14: Displaying Any Image - Continued

In the previous examples, we would use a pixel function to generate different shapes by placing each of their pixels in a specific location inside an array. Then we would use a Flush function to display the array’s data on the screen, showing the desired figure. In this case, instead of generating the values of our array buffer through the use of iterations, we give the array 1024 bytes of data that represent the image that we want to display.

This allows us to display any image we want, but with certain limitations. So how do we get these values? First we need to find the image that we want to display. We have to make sure the image is 128x64 (the resolution of our screen) and monochrome (black and white).

I borrowed mine from the internet: Mickey Mouse.

Step 15: Displaying Any Image - Continued

Once we have selected our image, we have to convert it from jpeg to bitmap.

This is simply done by opening the image in paint and saving it as a monochrome bitmap (.bmp). We can use other graphic software to convert the image if we want. Then, with the help of LCD Assistant, we can load the bmp image and save it as a cpp file. This will generate the desired array values that we need in our code to display the image. When the program is run we get the image displayed on our screen.

Step 16: Displaying Any Image - Continued

Here is another example with Jaycon Systems company logo.

That's it! Now you know how to display images on your OLED screen.

If you have any questions about this tutorial, do not hesitate to post a comment, shoot us an email, or post it in our forum!

Check out Jaycon Systems' website and Instructable page for more great tutorials.

Ready to start creating? Jaycon Systems online store has what you need for your project.

Thanks for reading!

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