This post shows how to interface PIC18F46K22 microcontroller with SSD1306 OLED (128×64 pixel).
The SSD1306 is a monochrome display which means it has only one color (white, blue, yellow …).
This display communicates with the master device over I2C mode, SPI mode or 8-bit parallel mode.
This topic shows how to use the SSD1306 OLED in I2C mode.
CCS C Compiler is used in this project.
SPI: Serial Peripheral Interface.
I2C (or IIC): Inter-Integrated Circuit.
Last time I made a simple interfacing of the PIC18F46K22 MCU and the SSD1306 OLED display which was used in SPI mode, project link is below:
PIC18F46K22 with SSD1306 OLED Display – SPI Mode Example
The SSD1306 OLED display used in this project is configured to work in I2C mode, some SSD1306 OLED boards may require a small hardware modifications (to select between SPI mode and I2C mode) such as soldering, placing jumpers …
Hardware Required:
- PIC18F46K22 microcontroller —-> datasheet
- SSD1306 OLED display
- 5V source
- Breadboard
- Jumper wires
PIC18F46K22 with SSD1306 OLED display circuit (I2C mode):
Example circuit diagram is shown below.
The SSD1306 OLED display module shown in the circuit diagram has 7 pins (from left to right):
GND, VCC, SCK (serial clock), SDA (serial data), RES (reset), DC (or D/C: data/command) and CS (chip select).
The SSD1306 display board is supplied with 5V where GND is connected to circuit ground and VCC is connected to +5V.
All the grounded terminals are connected together.
The PIC18F46K22 microcontroller has 2 hardware I2C modules (MSSP1 and MSSP2 modules).
In this project I2C1 module is used with SDA1 on pin RC4 (#23) and SCL1 on pin RC3 (#18). The SDA1 pin of the MCU is connected to the SDA pin of the display and the SCL1 pin of the MCU is connected to the SCL pin of the display.
The reset pin of the display (RES) is connected to pin RD4 (#27) of the microcontroller.
Chip select pin of the display (CS) is not connected (not used in I2C mode).
The SSD1306 OLED display DC pin is connected to VDD which means I2C slave address of the device is 0x7A. If the DC pin is connected to ground (GND) then the I2C slave address becomes 0x78.
In this project the PIC18F46K22 microcontroller runs with its internal oscillator @ 32 MHz, MCLR pin is configured as an input pin.
PIC18F46K22 with SSD1306 OLED display C code (I2C mode):
The following C code is for CCS C compiler, it was tested with versions 5.051 and 5.083.
To be able to compile project C code with no error, 2 libraries are required:
The first library is a driver for the SSD1306 OLED display, its full name (with extension) is SSD1306.c, download link is below:
SSD1306 OLED display library for CCS C compiler
The second library is graphics library, its full name is GFX_Library.c, download link is the one below:
Graphics library for CCS C compiler
after the download of the 2 library files, add both of them to the project folder.
Hints:
The 2 library files are included in the main code as shown below:
1 2 | #include <SSD1306.c> // include SSD1306 driver source code #include <GFX_Library.c> // include graphics library source code |
The reset pin of the display is connected to pin RD4 and it’s defined as (if the display module doesn’t have a reset pin then there is no need to define it):
1 2 | // SSD1306 OLED reset pin (if available) #define SSD1306_RST PIN_D4 |
The SSD1306 display is connected to hardware I2C module of the PIC18F46K22 which is initialized using the #use function (CCS C built-in function) with clock frequency of 400kHz:
1 | #use I2C(MASTER, I2C1, FAST = 400000, SMBUS, STREAM = SSD1306) |
The SSD1306 OLED display is initialized with I2C address 0x7A (because DC pin is connected to VDD):
1 2 3 4 | // by default, we'll generate the high voltage from the 3.3v line internally! (neat!) // initialize with the I2C addr 0x7A (for the 128x64) // SSD1306 OLED display I2C address may be 0x7A or 0x78 SSD1306_begin(SSD1306_SWITCHCAPVCC, 0x7A); |
Rest of code is described through comments.
Full CCS C code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 | /************************************************************************** Interfacing PIC18F46K22 MCU with SSD1306 OLED display (I2C mode). C Code for CCS C compiler. This is a free software with NO WARRANTY. http://simple-circuit.com/ /********************************************************************* This is an example for our Monochrome OLEDs based on SSD1306 drivers Pick one up today in the adafruit shop! ------> http://www.adafruit.com/category/63_98 This example is for a 128x64 size display using I2C to communicate 3 pins are required to interface (2 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. BSD license, check license.txt for more information All text above, and the splash screen must be included in any redistribution *********************************************************************/ // SSD1306 OLED reset pin (if available) #define SSD1306_RST PIN_D4 #include <18F46K22.h> #fuses NOMCLR,NOLVP,NOBROWNOUT,PUT,NOXINST #use delay(internal = 32MHz) #use I2C(MASTER, I2C1, FAST = 400000, SMBUS, STREAM = SSD1306) #include <SSD1306.c> // include SSD1306 driver source code #include <GFX_Library.c> // include graphics library source code // define random max number #define RAND_MAX (display_width - 1) // include std library source code (required by rand() function) #include <stdlib.h> #define NUMFLAKES 10 #define XPOS 0 #define YPOS 1 #define DELTAY 2 #define LOGO16_GLCD_HEIGHT 16 #define LOGO16_GLCD_WIDTH 16 rom char logo16_glcd_bmp[] = { 0b00000000, 0b11000000, 0b00000001, 0b11000000, 0b00000001, 0b11000000, 0b00000011, 0b11100000, 0b11110011, 0b11100000, 0b11111110, 0b11111000, 0b01111110, 0b11111111, 0b00110011, 0b10011111, 0b00011111, 0b11111100, 0b00001101, 0b01110000, 0b00011011, 0b10100000, 0b00111111, 0b11100000, 0b00111111, 0b11110000, 0b01111100, 0b11110000, 0b01110000, 0b01110000, 0b00000000, 0b00110000 }; void testdrawbitmap(rom uint8_t *bitmap, uint8_t w, uint8_t h) { static uint8_t icons[NUMFLAKES][3], f, x_pos, y_pos; // initialize for (f=0; f< NUMFLAKES; f++) { icons[f][XPOS] = rand(); icons[f][YPOS] = 0; icons[f][DELTAY] = (rand() % 5) + 1; } while (TRUE) { uint8_t f; // draw each icon for (f=0; f< NUMFLAKES; f++) { x_pos = icons[f][XPOS]; y_pos = icons[f][YPOS]; display_drawBitmapV2(x_pos, y_pos, bitmap, w, h, WHITE); } display(); delay_ms(200); // then erase it + move it for (f=0; f< NUMFLAKES; f++) { x_pos = icons[f][XPOS]; y_pos = icons[f][YPOS]; display_drawBitmapV2(x_pos, y_pos, bitmap, w, h, BLACK); // move it icons[f][YPOS] += icons[f][DELTAY]; // if its gone, reinit if (icons[f][YPOS] > display_height) { icons[f][XPOS] = rand(); icons[f][YPOS] = 0; icons[f][DELTAY] = (rand() % 5) + 1; } } } } void testdrawchar(void) { display_setTextSize(1); display_setTextColor(WHITE); display_setCursor(0, 0); for (uint8_t i=0; i < 170; i++) { if (i == '\n' || i == '\r') continue; display_print(i); } display(); delay_ms(1); } void testdrawcircle(void) { for (int16_t i=0; i<display_height; i+=2) { display_drawCircle(display_width/2, display_height/2, i, WHITE); display(); delay_ms(1); } } void testfillrect(void) { uint8_t color = 1; for (int16_t i=0; i<display_height/2; i+=3) { // alternate colors display_fillRect(i, i, display_width-i*2, display_height-i*2, color%2); display(); delay_ms(1); color++; } } void testdrawtriangle(void) { for (int16_t i=0; i<min(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(); delay_ms(1); } } void testfilltriangle(void) { uint8_t color = WHITE; for (int16_t i=min(display_width,display_height)/2; i>0; i-=5) { 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, WHITE); if (color == WHITE) color = BLACK; else color = WHITE; display(); delay_ms(1); } } void testdrawroundrect(void) { 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(); delay_ms(1); } } void testfillroundrect(void) { uint8_t color = WHITE; for (int16_t i=0; i<display_height/2-2; i+=2) { display_fillRoundRect(i, i, display_width-2*i, display_height-2*i, display_height/4, color); if (color == WHITE) color = BLACK; else color = WHITE; display(); delay_ms(1); } } void testdrawrect(void) { 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(); delay_ms(1); } } void testdrawline() { int16_t i; for (i=0; i<display_width; i+=4) { display_drawLine(0, 0, i, display_height-1, WHITE); display(); delay_ms(1); } for (i=0; i<display_height; i+=4) { display_drawLine(0, 0, display_width-1, i, WHITE); display(); delay_ms(1); } delay_ms(250); display_clear(); for (i=0; i<display_width; i+=4) { display_drawLine(0, display_height-1, i, 0, WHITE); display(); delay_ms(1); } for (i=display_height-1; i>=0; i-=4) { display_drawLine(0, display_height-1, display_width-1, i, WHITE); display(); delay_ms(1); } delay_ms(250); display_clear(); for (i=display_width-1; i>=0; i-=4) { display_drawLine(display_width-1, display_height-1, i, 0, WHITE); display(); delay_ms(1); } for (i=display_height-1; i>=0; i-=4) { display_drawLine(display_width-1, display_height-1, 0, i, WHITE); display(); delay_ms(1); } delay_ms(250); display_clear(); for (i=0; i<display_height; i+=4) { display_drawLine(display_width-1, 0, 0, i, WHITE); display(); delay_ms(1); } for (i=0; i<display_width; i+=4) { display_drawLine(display_width-1, 0, i, display_height-1, WHITE); display(); delay_ms(1); } delay_ms(250); } void testscrolltext(void) { display_setTextSize(2); display_setTextColor(WHITE); display_setCursor(10,0); display_clear(); display_print("scroll\r\n"); display(); delay_ms(1); display_startscrollright(0x00, 0x0F); delay_ms(2000); display_stopscroll(); delay_ms(1000); display_startscrollleft(0x00, 0x0F); delay_ms(2000); display_stopscroll(); delay_ms(1000); display_startscrolldiagright(0x00, 0x07); delay_ms(2000); display_startscrolldiagleft(0x00, 0x07); delay_ms(2000); display_stopscroll(); } // main function void main(void) { // by default, we'll generate the high voltage from the 3.3v line internally! (neat!) // initialize with the I2C addr 0x7A (for the 128x64) // SSD1306 OLED display I2C address may be 0x7A or 0x78 SSD1306_begin(SSD1306_SWITCHCAPVCC, 0x7A); // init done // Show image buffer on the display hardware. // Since the buffer is intialized with an Adafruit splashscreen // internally, this will display the splashscreen. display(); delay_ms(2000); // Clear the buffer. display_clear(); // draw a single pixel display_drawPixel(10, 10, WHITE); // Show the display buffer on the hardware. // NOTE: You _must_ call display after making any drawing commands // to make them visible on the display hardware! display(); delay_ms(2000); display_clear(); // draw many lines testdrawline(); display(); delay_ms(2000); display_clear(); // draw rectangles testdrawrect(); display(); delay_ms(2000); display_clear(); // draw multiple rectangles testfillrect(); display(); delay_ms(2000); display_clear(); // draw mulitple circles testdrawcircle(); display(); delay_ms(2000); display_clear(); // draw a white circle, 10 pixel radius display_fillCircle(display_width/2, display_height/2, 10, WHITE); display(); delay_ms(2000); display_clear(); testdrawroundrect(); delay_ms(2000); display_clear(); testfillroundrect(); delay_ms(2000); display_clear(); testdrawtriangle(); delay_ms(2000); display_clear(); testfilltriangle(); delay_ms(2000); display_clear(); // draw the first ~12 characters in the font testdrawchar(); display(); delay_ms(2000); display_clear(); // draw scrolling text testscrolltext(); delay_ms(2000); display_clear(); // text display tests display_setTextSize(1); display_setTextColor(WHITE); display_setCursor(0, 0); display_print("Hello, world!\r\n"); display_setTextColor(BLACK, WHITE); // 'inverted' text printf(display_print, "%f\r\n", 3.141592); display_setTextSize(2); display_setTextColor(WHITE); printf(display_print, "0x%LX\r\n", 0xDEADBEEF); display(); delay_ms(2000); display_clear(); // miniature bitmap display display_drawBitmapV2(30, 16, logo16_glcd_bmp, 16, 16, WHITE); display(); delay_ms(1); // invert the display display_invert(true); delay_ms(1000); display_invert(false); delay_ms(1000); display_clear(); // draw a bitmap icon and 'animate' movement testdrawbitmap(logo16_glcd_bmp, LOGO16_GLCD_HEIGHT, LOGO16_GLCD_WIDTH); } // end of code. |
Protoboard circuit test is shown in the following video:
Proteus simulation:
The video below shows Proteus simulation of this example, it gave approximately the same result as the real hardware circuit:
Proteus simulation file download link is below, use version 8.6 or higher to open it:
PIC18F46K22 + SSD1306 OLED I2C mode
