/** * Copyright (c) 2021 Raspberry Pi (Trading) Ltd. * * SPDX-License-Identifier: BSD-3-Clause */ #include <stdio.h> #include <string.h> #include <stdlib.h> #include <ctype.h> #include "pico/stdlib.h" #include "pico/binary_info.h" #include "hardware/i2c.h" #include "raspberry26x32.h" #include "ssd1306_font.h" /* Example code to talk to an SSD1306-based OLED display The SSD1306 is an OLED/PLED driver chip, capable of driving displays up to 128x64 pixels. NOTE: Ensure the device is capable of being driven at 3.3v NOT 5v. The Pico GPIO (and therefore I2C) cannot be used at 5v. You will need to use a level shifter on the I2C lines if you want to run the board at 5v. Connections on Raspberry Pi Pico board, other boards may vary. GPIO PICO_DEFAULT_I2C_SDA_PIN (on Pico this is GP4 (pin 6)) -> SDA on display board GPIO PICO_DEFAULT_I2C_SCL_PIN (on Pico this is GP5 (pin 7)) -> SCL on display board 3.3v (pin 36) -> VCC on display board GND (pin 38) -> GND on display board */ // Define the size of the display we have attached. This can vary, make sure you // have the right size defined or the output will look rather odd! // Code has been tested on 128x32 and 128x64 OLED displays #define SSD1306_HEIGHT 32 #define SSD1306_WIDTH 128 #define SSD1306_I2C_ADDR _u(0x3C) // 400 is usual, but often these can be overclocked to improve display response. // Tested at 1000 on both 32 and 84 pixel height devices and it worked. #define SSD1306_I2C_CLK 400 //#define SSD1306_I2C_CLK 1000 // commands (see datasheet) #define SSD1306_SET_MEM_MODE _u(0x20) #define SSD1306_SET_COL_ADDR _u(0x21) #define SSD1306_SET_PAGE_ADDR _u(0x22) #define SSD1306_SET_HORIZ_SCROLL _u(0x26) #define SSD1306_SET_SCROLL _u(0x2E) #define SSD1306_SET_DISP_START_LINE _u(0x40) #define SSD1306_SET_CONTRAST _u(0x81) #define SSD1306_SET_CHARGE_PUMP _u(0x8D) #define SSD1306_SET_SEG_REMAP _u(0xA0) #define SSD1306_SET_ENTIRE_ON _u(0xA4) #define SSD1306_SET_ALL_ON _u(0xA5) #define SSD1306_SET_NORM_DISP _u(0xA6) #define SSD1306_SET_INV_DISP _u(0xA7) #define SSD1306_SET_MUX_RATIO _u(0xA8) #define SSD1306_SET_DISP _u(0xAE) #define SSD1306_SET_COM_OUT_DIR _u(0xC0) #define SSD1306_SET_COM_OUT_DIR_FLIP _u(0xC0) #define SSD1306_SET_DISP_OFFSET _u(0xD3) #define SSD1306_SET_DISP_CLK_DIV _u(0xD5) #define SSD1306_SET_PRECHARGE _u(0xD9) #define SSD1306_SET_COM_PIN_CFG _u(0xDA) #define SSD1306_SET_VCOM_DESEL _u(0xDB) #define SSD1306_PAGE_HEIGHT _u(8) #define SSD1306_NUM_PAGES (SSD1306_HEIGHT / SSD1306_PAGE_HEIGHT) #define SSD1306_BUF_LEN (SSD1306_NUM_PAGES * SSD1306_WIDTH) #define SSD1306_WRITE_MODE _u(0xFE) #define SSD1306_READ_MODE _u(0xFF) struct render_area { uint8_t start_col; uint8_t end_col; uint8_t start_page; uint8_t end_page; int buflen; }; void calc_render_area_buflen(struct render_area *area) { // calculate how long the flattened buffer will be for a render area area->buflen = (area->end_col - area->start_col + 1) * (area->end_page - area->start_page + 1); } #ifdef i2c_default void SSD1306_send_cmd(uint8_t cmd) { // I2C write process expects a control byte followed by data // this "data" can be a command or data to follow up a command // Co = 1, D/C = 0 => the driver expects a command uint8_t buf[2] = {0x80, cmd}; i2c_write_blocking(i2c_default, SSD1306_I2C_ADDR, buf, 2, false); } void SSD1306_send_cmd_list(uint8_t *buf, int num) { for (int i=0;i<num;i++) SSD1306_send_cmd(buf[i]); } void SSD1306_send_buf(uint8_t buf[], int buflen) { // in horizontal addressing mode, the column address pointer auto-increments // and then wraps around to the next page, so we can send the entire frame // buffer in one gooooooo! // copy our frame buffer into a new buffer because we need to add the control byte // to the beginning uint8_t *temp_buf = malloc(buflen + 1); temp_buf[0] = 0x40; memcpy(temp_buf+1, buf, buflen); i2c_write_blocking(i2c_default, SSD1306_I2C_ADDR, temp_buf, buflen + 1, false); free(temp_buf); } void SSD1306_init() { // Some of these commands are not strictly necessary as the reset // process defaults to some of these but they are shown here // to demonstrate what the initialization sequence looks like // Some configuration values are recommended by the board manufacturer uint8_t cmds[] = { SSD1306_SET_DISP, // set display off /* memory mapping */ SSD1306_SET_MEM_MODE, // set memory address mode 0 = horizontal, 1 = vertical, 2 = page 0x00, // horizontal addressing mode /* resolution and layout */ SSD1306_SET_DISP_START_LINE, // set display start line to 0 SSD1306_SET_SEG_REMAP | 0x01, // set segment re-map, column address 127 is mapped to SEG0 SSD1306_SET_MUX_RATIO, // set multiplex ratio SSD1306_HEIGHT - 1, // Display height - 1 SSD1306_SET_COM_OUT_DIR | 0x08, // set COM (common) output scan direction. Scan from bottom up, COM[N-1] to COM0 SSD1306_SET_DISP_OFFSET, // set display offset 0x00, // no offset SSD1306_SET_COM_PIN_CFG, // set COM (common) pins hardware configuration. Board specific magic number. // 0x02 Works for 128x32, 0x12 Possibly works for 128x64. Other options 0x22, 0x32 #if ((SSD1306_WIDTH == 128) && (SSD1306_HEIGHT == 32)) 0x02, #elif ((SSD1306_WIDTH == 128) && (SSD1306_HEIGHT == 64)) 0x12, #else 0x02, #endif /* timing and driving scheme */ SSD1306_SET_DISP_CLK_DIV, // set display clock divide ratio 0x80, // div ratio of 1, standard freq SSD1306_SET_PRECHARGE, // set pre-charge period 0xF1, // Vcc internally generated on our board SSD1306_SET_VCOM_DESEL, // set VCOMH deselect level 0x30, // 0.83xVcc /* display */ SSD1306_SET_CONTRAST, // set contrast control 0xFF, SSD1306_SET_ENTIRE_ON, // set entire display on to follow RAM content SSD1306_SET_NORM_DISP, // set normal (not inverted) display SSD1306_SET_CHARGE_PUMP, // set charge pump 0x14, // Vcc internally generated on our board SSD1306_SET_SCROLL | 0x00, // deactivate horizontal scrolling if set. This is necessary as memory writes will corrupt if scrolling was enabled SSD1306_SET_DISP | 0x01, // turn display on }; SSD1306_send_cmd_list(cmds, count_of(cmds)); } void SSD1306_scroll(bool on) { // configure horizontal scrolling uint8_t cmds[] = { SSD1306_SET_HORIZ_SCROLL | 0x00, 0x00, // dummy byte 0x00, // start page 0 0x00, // time interval 0x03, // end page 3 SSD1306_NUM_PAGES ?? 0x00, // dummy byte 0xFF, // dummy byte SSD1306_SET_SCROLL | (on ? 0x01 : 0) // Start/stop scrolling }; SSD1306_send_cmd_list(cmds, count_of(cmds)); } void render(uint8_t *buf, struct render_area *area) { // update a portion of the display with a render area uint8_t cmds[] = { SSD1306_SET_COL_ADDR, area->start_col, area->end_col, SSD1306_SET_PAGE_ADDR, area->start_page, area->end_page }; SSD1306_send_cmd_list(cmds, count_of(cmds)); SSD1306_send_buf(buf, area->buflen); } static void SetPixel(uint8_t *buf, int x,int y, bool on) { assert(x >= 0 && x < SSD1306_WIDTH && y >=0 && y < SSD1306_HEIGHT); // The calculation to determine the correct bit to set depends on which address // mode we are in. This code assumes horizontal // The video ram on the SSD1306 is split up in to 8 rows, one bit per pixel. // Each row is 128 long by 8 pixels high, each byte vertically arranged, so byte 0 is x=0, y=0->7, // byte 1 is x = 1, y=0->7 etc // This code could be optimised, but is like this for clarity. The compiler // should do a half decent job optimising it anyway. const int BytesPerRow = SSD1306_WIDTH ; // x pixels, 1bpp, but each row is 8 pixel high, so (x / 8) * 8 int byte_idx = (y / 8) * BytesPerRow + x; uint8_t byte = buf[byte_idx]; if (on) byte |= 1 << (y % 8); else byte &= ~(1 << (y % 8)); buf[byte_idx] = byte; } // Basic Bresenhams. static void DrawLine(uint8_t *buf, int x0, int y0, int x1, int y1, bool on) { int dx = abs(x1-x0); int sx = x0<x1 ? 1 : -1; int dy = -abs(y1-y0); int sy = y0<y1 ? 1 : -1; int err = dx+dy; int e2; while (true) { SetPixel(buf, x0, y0, on); if (x0 == x1 && y0 == y1) break; e2 = 2*err; if (e2 >= dy) { err += dy; x0 += sx; } if (e2 <= dx) { err += dx; y0 += sy; } } } static inline int GetFontIndex(uint8_t ch) { if (ch >= 'A' && ch <='Z') { return ch - 'A' + 1; } else if (ch >= '0' && ch <='9') { return ch - '0' + 27; } else return 0; // Not got that char so space. } static void WriteChar(uint8_t *buf, int16_t x, int16_t y, uint8_t ch) { if (x > SSD1306_WIDTH - 8 || y > SSD1306_HEIGHT - 8) return; // For the moment, only write on Y row boundaries (every 8 vertical pixels) y = y/8; ch = toupper(ch); int idx = GetFontIndex(ch); int fb_idx = y * 128 + x; for (int i=0;i<8;i++) { buf[fb_idx++] = font[idx * 8 + i]; } } static void WriteString(uint8_t *buf, int16_t x, int16_t y, char *str) { // Cull out any string off the screen if (x > SSD1306_WIDTH - 8 || y > SSD1306_HEIGHT - 8) return; while (*str) { WriteChar(buf, x, y, *str++); x+=8; } } #endif int main() { stdio_init_all(); #if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN) #warning i2c / SSD1306_i2d example requires a board with I2C pins puts("Default I2C pins were not defined"); #else // useful information for picotool bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C)); bi_decl(bi_program_description("SSD1306 OLED driver I2C example for the Raspberry Pi Pico")); printf("Hello, SSD1306 OLED display! Look at my raspberries..\n"); // I2C is "open drain", pull ups to keep signal high when no data is being // sent i2c_init(i2c_default, SSD1306_I2C_CLK * 1000); gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C); gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C); gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN); gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN); // run through the complete initialization process SSD1306_init(); // Initialize render area for entire frame (SSD1306_WIDTH pixels by SSD1306_NUM_PAGES pages) struct render_area frame_area = { start_col: 0, end_col : SSD1306_WIDTH - 1, start_page : 0, end_page : SSD1306_NUM_PAGES - 1 }; calc_render_area_buflen(&frame_area); // zero the entire display uint8_t buf[SSD1306_BUF_LEN]; memset(buf, 0, SSD1306_BUF_LEN); render(buf, &frame_area); // intro sequence: flash the screen 3 times for (int i = 0; i < 3; i++) { SSD1306_send_cmd(SSD1306_SET_ALL_ON); // Set all pixels on sleep_ms(500); SSD1306_send_cmd(SSD1306_SET_ENTIRE_ON); // go back to following RAM for pixel state sleep_ms(500); } // render 3 cute little raspberries struct render_area area = { start_page : 0, end_page : (IMG_HEIGHT / SSD1306_PAGE_HEIGHT) - 1 }; restart: area.start_col = 0; area.end_col = IMG_WIDTH - 1; calc_render_area_buflen(&area); uint8_t offset = 5 + IMG_WIDTH; // 5px padding for (int i = 0; i < 3; i++) { render(raspberry26x32, &area); area.start_col += offset; area.end_col += offset; } SSD1306_scroll(true); sleep_ms(5000); SSD1306_scroll(false); char *text[] = { "A long time ago", " on an OLED ", " display", " far far away", "Lived a small", "red raspberry", "by the name of", " PICO" }; int y = 0; for (uint i = 0 ;i < count_of(text); i++) { WriteString(buf, 5, y, text[i]); y+=8; } render(buf, &frame_area); // Test the display invert function sleep_ms(3000); SSD1306_send_cmd(SSD1306_SET_INV_DISP); sleep_ms(3000); SSD1306_send_cmd(SSD1306_SET_NORM_DISP); bool pix = true; for (int i = 0; i < 2;i++) { for (int x = 0;x < SSD1306_WIDTH;x++) { DrawLine(buf, x, 0, SSD1306_WIDTH - 1 - x, SSD1306_HEIGHT - 1, pix); render(buf, &frame_area); } for (int y = SSD1306_HEIGHT-1; y >= 0 ;y--) { DrawLine(buf, 0, y, SSD1306_WIDTH - 1, SSD1306_HEIGHT - 1 - y, pix); render(buf, &frame_area); } pix = false; } goto restart; #endif return 0; }

This firmware image was imported from the pico-examples repository. 


Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
   disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
   derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.