SSD1309 IIC驱动

SSD1309是一款常用的OLED显示屏驱动芯片，支持I2C和SPI两种通信协议。下面是基于I2C协议的驱动代码示例：

首先，需要定义一些寄存器地址和常量：

#define SSD1309_I2C_ADDRESS   0x3C
#define SSD1309_WIDTH         128
#define SSD1309_HEIGHT        64

#define SSD1309_SETCONTRAST   0x81
#define SSD1309_DISPLAYALLON_RESUME   0xA4
#define SSD1309_DISPLAYALLON  0xA5
#define SSD1309_NORMALDISPLAY 0xA6
#define SSD1309_INVERTDISPLAY 0xA7
#define SSD1309_DISPLAYOFF    0xAE
#define SSD1309_DISPLAYON     0xAF
#define SSD1309_SETDISPLAYOFFSET 0xD3
#define SSD1309_SETCOMPINS    0xDA
#define SSD1309_SETVCOMDETECT 0xDB
#define SSD1309_SETDISPLAYCLOCKDIV 0xD5
#define SSD1309_SETPRECHARGE  0xD9
#define SSD1309_SETMULTIPLEX  0xA8
#define SSD1309_SETLOWCOLUMN  0x00
#define SSD1309_SETHIGHCOLUMN 0x10
#define SSD1309_SETSTARTLINE  0x40
#define SSD1309_MEMORYMODE    0x20
#define SSD1309_COLUMNADDR    0x21
#define SSD1309_PAGEADDR      0x22
#define SSD1309_COMSCANINC    0xC0
#define SSD1309_COMSCANDEC    0xC8
#define SSD1309_SEGREMAP      0xA0
#define SSD1309_CHARGEPUMP    0x8D

#define SSD1309_EXTERNALVCC   0x1
#define SSD1309_SWITCHCAPVCC  0x2

然后，初始化I2C总线和SSD1309 OLED驱动：

#include <Wire.h>

void ssd1309_init() {
  Wire.beginTransmission(SSD1309_I2C_ADDRESS);
  Wire.write(SSD1309_DISPLAYOFF);
  Wire.write(SSD1309_SETDISPLAYCLOCKDIV);
  Wire.write(0x80);
  Wire.write(SSD1309_SETMULTIPLEX);
  Wire.write(0x3F);
  Wire.write(SSD1309_SETDISPLAYOFFSET);
  Wire.write(0x00);
  Wire.write(SSD1309_SETSTARTLINE | 0x00);
  Wire.write(SSD1309_CHARGEPUMP);
  Wire.write(0x14);
  Wire.write(SSD1309_MEMORYMODE);
  Wire.write(0x00);
  Wire.write(SSD1309_SEGREMAP | 0x01);
  Wire.write(SSD1309_COMSCANDEC);
  Wire.write(SSD1309_SETCOMPINS);
  Wire.write(0x12);
  Wire.write(SSD1309_SETCONTRAST);
  Wire.write(0xCF);
  Wire.write(SSD1309_SETPRECHARGE);
  Wire.write(0xF1);
  Wire.write(SSD1309_SETVCOMDETECT);
  Wire.write(0x40);
  Wire.write(SSD1309_DISPLAYALLON_RESUME);
  Wire.write(SSD1309_NORMALDISPLAY);
  Wire.write(SSD1309_DISPLAYON);
  Wire.endTransmission();
}

接下来是一些常用的函数，比如设置显示位置、清屏、写入数据等：

void ssd1309_set_position(unsigned char x, unsigned char y) {
  Wire.beginTransmission(SSD1309_I2C_ADDRESS);
  Wire.write(SSD1309_COLUMNADDR);
  Wire.write(x);
  Wire.write(SSD1309_WIDTH - 1);
  Wire.write(SSD1309_PAGEADDR);
  Wire.write(y);
  Wire.write((SSD1309_HEIGHT / 8) - 1);
  Wire.endTransmission();
}

void ssd1309_clear_screen() {
  for (int i = 0; i < (SSD1309_WIDTH * SSD1309_HEIGHT / 8); i++) {
    Wire.beginTransmission(SSD1309_I2C_ADDRESS);
    Wire.write(0x40);
    Wire.write(0x00);
    Wire.endTransmission();
  }
}

void ssd1309_write_data(unsigned char data) {
  Wire.beginTransmission(SSD1309_I2C_ADDRESS);
  Wire.write(0x40);
  Wire.write(data);
  Wire.endTransmission();
}

最后，使用上面的函数就可以在OLED屏幕上显示文字或图像了：

ssd1309_init();  // 初始化

ssd1309_set_position(0, 0);  // 设置位置
for (int i = 0; i < (SSD1309_WIDTH * SSD1309_HEIGHT / 8); i++) {
  ssd1309_write_data(0xFF);  // 写入数据
}

ssd1309_clear_screen();  // 清屏

以上是基于I2C协议的驱动代码示例，使用SPI协议的驱动方式类似，只需要修改一些通信方式的细节就可以了。