/**
* 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.
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