【Raspberry Pi Pico】OLEDディスプレイ(SSD1306)に文字を表示する

#define I2C_SDA_PIN 4
#define I2C_SCL_PIN 5

int main(void)
{
    // This example will use I2C0 on the default SDA and SCL pins (4, 5 on a Pico)
    i2c_init(i2c_default, 100 * 1000);
    gpio_set_function(I2C_SDA_PIN, GPIO_FUNC_I2C);
    gpio_set_function(I2C_SCL_PIN, GPIO_FUNC_I2C);
    gpio_pull_up(I2C_SDA_PIN);
    gpio_pull_up(I2C_SCL_PIN);
    // Make the I2C pins available to picotool
    bi_decl(bi_2pins_with_func(I2C_SDA_PIN, I2C_SCL_PIN, GPIO_FUNC_I2C));
：

#ifndef __OLED_SSD1306_H_
#define __OLED_SSD1306_H_

#define SSD1306_ADDR            0x3C

#define I2C_SPEED_STANDARD      100000
#define I2C_SPEED_DOUBLE        200000
#define I2C_SPEED_FAST          400000

// Control byte
#define SSD1306_CONTROL_CMD_SINGLE      0x80
#define SSD1306_CONTROL_CMD_STREAM      0x00
#define SSD1306_CONTROL_DATA_STREAM     0x40

// Fundamental commands (pg.28)
#define SSD1306_SET_CONTRAST            0x81
#define SSD1306_DISPLAY_ALL_ON_RESUME   0xA4
#define SSD1306_DISPLAY_ALL_ON_IGNORE   0xA5
#define SSD1306_NORMAL_DISPLAY          0xA6
#define SSD1306_INVERT_DISPLAY          0xA7
#define SSD1306_DISPLAY_OFF             0xAE
#define SSD1306_DISPLAY_ON              0xAF

// Scrolling #defines (pg.28-30)
#define SSD1306_RIGHT_HORIZONTAL_SCROLL                 0x26
#define SSD1306_LEFT_HORIZONTAL_SCROLL                  0x27
#define SSD1306_VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL    0x29
#define SSD1306_VERTICAL_AND_LEFT_HORIZONTAL_SCROLL     0x2A
#define SSD1306_DEACTIVATE_SCROLL                       0x2E
#define SSD1306_ACTIVATE_SCROLL                         0x2F
#define SSD1306_SET_VERTICAL_SCROLL_AREA                0xA3

// Addressing Command Table (pg.30)
#define SSD1306_SET_LOW_COLUMN          0x00
#define SSD1306_SET_HIGH_COLUMN         0x10
#define SSD1306_SET_MEMORY_ADDR_MODE    0x20    // follow with 0x00 = HORZ mode = Behave like a KS108 graphic LCD
#define SSD1306_SET_COLUMN_RANGE        0x21    // can be used only in HORZ/VERT mode - follow with 0x00 and 0x7F = COL127
#define SSD1306_SET_PAGE_RANGE          0x22    // can be used only in HORZ/VERT mode - follow with 0x00 and 0x07 = PAGE7
#define SSD1306_SET_PAGE_START_ADDRESS  0xB0

// Hardware Config (pg.31)
#define SSD1306_SET_DISPLAY_START_LINE  0x40
#define SSD1306_SET_SEGMENT_REMAP_LOW   0xA0
#define SSD1306_SET_SEGMENT_REMAP_HIGH  0xA1
#define SSD1306_SET_MULTIPLEX_RATIO     0xA8    // follow with 0x3F = 64 MUX
#define SSD1306_SET_COM_SCAN_INC        0xC0
#define SSD1306_SET_COM_SCAN_DEC        0xC8
#define SSD1306_SET_DISPLAY_OFFSET      0xD3    // follow with 0x00
#define SSD1306_SET_COM_PIN_MAP         0xDA    // follow with 0x12

// Timing and Driving Scheme (pg.32)
#define SSD1306_SET_DISPLAY_CLK_DIV     0xD5    // follow with 0x80
#define SSD1306_SET_PRECHARGE           0xD9    // follow with 0xF1
#define SSD1306_SET_VCOMH_DESELCT       0xDB    // follow with 0x30
#define SSD1306_NOP                     0xE3    // NOP

// Charge Pump (pg.62)
#define SSD1306_SET_CHARGE_PUMP         0x8D    // follow with 0x14

#endif

static void OLED_SSD1306_init(void)
{
    uint8_t buf[29];
    
    buf[0] = SSD1306_CONTROL_CMD_STREAM;                /* コントロールバイト */
    
    /* Display off */
    buf[1] = SSD1306_DISPLAY_OFF;
    
    /* Set MUX Ratio A8h, 3Fh*/
    buf[2] = SSD1306_SET_MULTIPLEX_RATIO;
    buf[3] =0x3F;
    
    /* Set Display Offset D3h, 00h */
    buf[4] = SSD1306_SET_DISPLAY_OFFSET;
    buf[5] = 0x00;
    
    /* Set Display Start Line 40h */
    buf[6] = SSD1306_SET_DISPLAY_START_LINE;
    
    /* Set Segment re-map A0h/A1h */
    buf[7] = SSD1306_SET_SEGMENT_REMAP_LOW;
    
    /* Set COM Output Scan Direction C0h/C8h */
    buf[8] = SSD1306_SET_COM_SCAN_INC;
    
    /* Set COM Pins hardware configuration DAh, 02*/
    buf[9] = SSD1306_SET_COM_PIN_MAP;
    buf[10] = 0x12;
    
    /* Set Contrast Control 81h, 7Fh */
    buf[11] = SSD1306_SET_CONTRAST;
    buf[12] = 0x7F;
    
    /* Disable Entire Display On A4h */
    buf[13] = SSD1306_DISPLAY_ALL_ON_RESUME;
    
    /* Set Normal Display A6h */
    buf[14] = SSD1306_NORMAL_DISPLAY;
    
    /* Set Osc Frequency D5h, 80h */
    buf[15] = SSD1306_SET_DISPLAY_CLK_DIV;
    buf[16] = 0x80; 
    
    buf[17] = SSD1306_SET_MEMORY_ADDR_MODE;
    buf[18] = 0x10;
    
    buf[19] = SSD1306_SET_COLUMN_RANGE;
    buf[20] = 0x00;
    buf[21] = 0x7F;
    
    buf[22] = SSD1306_SET_PAGE_RANGE;
    buf[23] = 0x00;
    buf[24] = 0x07;
    
    buf[25] = SSD1306_DEACTIVATE_SCROLL;
    
    /* Enable charge pump regulator 8Dh, 14h */
    buf[26] = SSD1306_SET_CHARGE_PUMP;
    buf[27] = 0x14;
    
    /* Display On AFh */
    buf[28] = SSD1306_DISPLAY_ON;
    
    (void)i2c_write_blocking (i2c_default, I2C_LED_ADDR, buf, 29, false);
    
    return;
}

static void OLED_SSD1306_clear(void)
{
    uint8_t i,j;
    uint8_t buf[9];
    
    for(i = 0; i < 8; i++) {
        buf[0] = SSD1306_CONTROL_CMD_STREAM;            /* コントロールバイト */
        buf[1] = SSD1306_SET_PAGE_START_ADDRESS | i;    /* set page start address(B0～B7) */
        buf[2] = SSD1306_SET_COLUMN_RANGE;              /* set Column Address */
        buf[3] = 0x00;                                  /* Column Start Address(0-127) */
        buf[4] = 0x7F;                                  /* Column Stop Address(0-127) */
        
        (void)i2c_write_blocking (i2c_default, I2C_LED_ADDR, buf, 5, false);
        
        buf[0] = SSD1306_CONTROL_DATA_STREAM;           /*  コントロールバイト */
        for(j = 0; j < 8; j++) {
            buf[1 + j] = 0x00;
        }
        for(j = 0; j < 16; j++) {
            (void)i2c_write_blocking (i2c_default, I2C_LED_ADDR, buf, 9, false);
        }
    }
    g_x = 0;
    g_y = 0;
    
    return;
}

static char* OLED_SSD1306_writeChar(char *data)
{
    uint8_t buf[9];
    
    if (*data == 0x0a) {
        OLED_SSD1306_newLine();
        data += 1;
    } else if ((*data == 0x5c) && (*(data + 1) == 0x6e)) {
        OLED_SSD1306_newLine();
        data += 2;
    } else if ((g_y < 8) && (g_x < 16)) {
        /* コマンド */
        buf[0] = SSD1306_CONTROL_CMD_STREAM;            /* コントロールバイト */
        buf[1] = SSD1306_SET_PAGE_START_ADDRESS | g_y;  /* ページ指定, 垂直位置 */
        buf[2] = SSD1306_SET_COLUMN_RANGE;              /* サブアドレス */
        buf[3] = g_x << 3;                              /* 水平位置 */
        buf[4] = (g_x << 3) + 7;                        /* 折り返し */
        (void)i2c_write_blocking (i2c_default, I2C_LED_ADDR, buf, 5, false);
        
        /* データ */
        buf[0] = SSD1306_CONTROL_DATA_STREAM;           /* コントロールバイト */
        data = getFontData(&buf[1], data, false);
        
        (void)i2c_write_blocking (i2c_default, I2C_LED_ADDR, buf, 9, false);
        g_x++;
    } else {
        ;
    }
    
    return data;
}

static void OLED_SSD1306_newLine(void)
{
    g_x = 0;
    if (g_y < 8) {
        g_y++;
    } else {
        g_y = 0;
    }
    
    return;
}

static void OLED_SSD1306_println(char *data)
{   
    do {
        data = OLED_SSD1306_writeChar(data);
    } while(*data != '\0');
    
    return;
}

static void rotateToRight(char *data)
{
    uint8_t i,j;
    uint8_t buf[8];
    
    for(i = 0; i < 8; i++) {
        buf[i] = 0;
    }
    
    for(i = 0 ; i < 8; i++) {
        for(j = 0 ; j < 8; j++) {
            buf[j] |= ((data[i] >> (7 - j)) & 1) << i;
        }
    }
    
    for(i = 0; i < 8; i++) {
        data[i] = buf[i];
    }
    
    return;
}