第七章 I2C
7.1 I2C通信¶
推荐阅读：I2C理论(含stm32软、硬件I2C)
建议掌握：软件模拟I2C
7.2 OLED显示屏¶
7.2.1 OLED简介¶
如图所示为一个0.96寸的OLED显示屏，其驱动芯片为SSD1306，使用I2C通信，从机地址为0x78。
本节关于OLED的介绍全部来源于SSD1306芯片数据手册。
7.2.2 从机地址¶
内容来源：SSD1306芯片数据手册 8.1.5 MUC I2C Interface
- 8Bit，其中高7位表示从机地址。
- “SA0” bit 是为了从机地址的灵活性，可以选择 “0111100” 或 “0111101” 为SSD1306芯片的从机地址。
- “R/W#” bit 是选择读写模式，R/W#=1 为读模式，R/W#=0 为写模式。
那么为什么说从机地址是0x78呢？
实际上我们说从机地址时，忽略最低位补零，那么默认的地址就是 0111100，也就是0x78。然而，在实际I2C通信中则不是直接发从机地址 ，而是加上读写位。如下图，在I2C通信时，若我们进入写模式，则末位补零，程序中可以使用0x78|0x00，读模式则为0x78|0x01。
7.2.3 显存(GDDRAM)¶
内容来源：SSD1306芯片数据手册8.7 Graphic Display Data RAM (GDDRAM)
如下图 RAM 大小是 128x64 Bits，被划分为 8 个pages，一个page有8像素点。 其中，绿色的计数方式为重映射后的，默认为黑色字体样式。
当一个字节的数据被写入 GDDRAM (也就是通过I2C发送一个字节数据)时，当前一page一列(8Bit)就会被点亮。注意低位在上，高位在下，如下图所示。
7.2.4 命令表¶
内容来源：SSD1306芯片数据手册9. COMMAND TABLE
展示一些常用的命令：
| 代码（16进制） | 命令 | 说明 |
|---|---|---|
| 81+xx | 设置对比度 | 两个字节的命令，xx 的范围为 0~255，值越大，对比度越高。 |
| A4/A5 | 开启／关闭整体显示 | A4：将显存内容输出到屏幕。 A5：输出时忽略显存内容。 |
| A6/A7 | 设置正常／反色显示 | A6：正常显示。0对应像素熄灭，1对应像素亮起。 A7：反色显示。0对应像素亮起，1对应像素熄灭。 |
| AE/AF | 设置显示开／关 | AE：显示关闭（睡眠模式，默认状态）。 AF：显示开启（正常模式）。 |
| B0~B7 | 在页寻址模式时，设置页面起始地址 | 设置GDDRAM页面起始地址（PAGE0~PAGE7）。 |
| 00~0F | 在页寻址模式时，设置列地址的低4位 | 列地址范围为 0~127，即 0x00~0x7f。 |
| 10~1F | 在页寻址模式时，设置列地址的高4位 | 列地址的高 4 位需要和0x10进行按位或作为值。 |
C
0xAE, // 显示关闭
0x00, // 页寻址模式时，设置列地址的低4位为0000
0x10, // 页寻址模式时，设置列地址的高4位为0000
0x40, // 设置起始行地址为第0行
0xB0, // 页寻址模式时，设置页面起始地址为PAGE0
0x81, // 设置对比度
0xFF, // 对比度值
0xA1, // set segment remap
0xA6, // 设置正常显示。0对应像素熄灭，1对应像素亮起
0xA8, // --set multiplex ratio(1 to 64)
0x3F, // --1/32 duty
0xC0, // scan direction
0xD3, // -set display offset
0x00, // set osc division
0xD5, // set osc division
0x80,
0xD8, // set area color mode off
0x05,
0xD9, // Set Pre-Charge Period
0xF1,
0xDA, // set com pin configuargtion
0x12,
0xDB, // set Vcomh
0x30, // set charge pump enable
0x8D, // set charge pump enable
0x14,
0xAF, // 显示开启
7.2.5 显存寻址模式¶
页寻址模式(0x20)
页寻址模式将整个显存划分为多个 “页”，每一页包含 8 行像素。同一页内的像素按列组织，写完一列的 8 个像素后，列地址自动加 1。当列地址达到该页的最大列数时，列地址会回到起始列，但页地址不会自动改变，需要通过专门的命令来切换页。对于 128x64 的 SSD1306 显示屏，会被划分为 8 页（编号 0 - 7），每页有 128 列。同时也寻址模式是 默认的寻址模式 。
水平寻址模式(0x21)
在水平寻址模式下，显存的读写操作是按照从左到右、从上到下的顺序逐列进行的。当写完一行的所有列后，会自动跳到下一行的起始列继续进行操作。如果到达了显存的最后一列，地址指针会自动回到第一列，同时行地址加 1；若到达最后一行，则地址指针回到第一行第一列。
垂直寻址模式(0x22)
垂直寻址模式下，显存的读写是按列进行的，先从上到下写完一列，再跳到下一列继续操作。当写完所有列后，列地址会回到起始列，同时行地址加 1。如果到达最后一行，则地址指针回到第一行第一列。
7.2.6 页寻址模式¶
- 按列写，从列0开始，到列127结束。每列一个字节数据，低位在上，高位在下。
- 列地址指针(RAM access pointer)，每读取或写入一个字节数据，列地址指针自动+1，到列127后返回列0。
- 设置起始页，相当于Y轴，命令0xB0 - 0xB7。
- 设置列地址低四位，命令0x00 - 0x0F。
- 设置列地址高四位，命令0x10 - 0x1F。
封装寻址为函数，用于确定X、Y坐标：
C
/**
* @param x: 横坐标，取值范围是0~127，对应128个像素点，x的单位为bit。
* @param y: 纵坐标，取值范围是0~7，对应8个pages，y的单位是字节(8bits)。
*/
void OledSetPosition(uint8_t x, uint8_t y)
{
/* 起始页(y坐标) */
WriteCmd(0xB0 + y);
/* 列地址低四位 */
WriteCmd(0x0F & x);
/* 列地址高四位 */
WriteCmd(0x10 | ((0xF0 & x) >> 4));
}
例：x= 0x5D = 93 = 0101 1101，y = 3
C
/* 起始页(y坐标) */
0xB0 + y = 0xB3 => page3
/* 列地址低四位 */
0x0F & x = 0000 1101 = 0x0D
/* 列地址高四位 */
0xF0 & x = 0101 0000
((0xF0 & x) >> 4) = 0000 0101
0x10 | ((0xF0 & x) >> 4) = 0001 0101 = 0x15
7.2.7 I2C写模式¶
需要特别注意的是，在发送完从机地址后我们需要发送一个 控制字节 指定要发送 命令 还是 数据 ，控制字节由Co位、D/C#位和六个0组成：
Co位，当C0=0表示后续传输的信息将仅包含数据字节，即不含控制字节。
D/C#位，其中D/C#=0则下一个字节为命令，D/C#=1则下一个字节为数据。
因此，发送命令的控制字节为 0x00 (C0=0且D/C#=0)；发送数据的控制字节为 0x40 (C0=0且D/C#=1)。
7.3 OLED简易驱动¶
7.3.1 OLED驱动代码¶
oled_fonts.h
C
#ifndef OLOED_FONTS_H
#define OLOED_FONTS_H
/************************************6*8的点阵************************************/
// 取模方式：纵向8点下高位
// 采用N*6的二维数组
// 第一维表示字符
// 每个字符对应第二维的6个数组元素，每个数组元素1字节，表示1列像素，一共6列8行
static unsigned char F6x8[][6] =
{
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, // 空格
{ 0x00, 0x00, 0x00, 0x2f, 0x00, 0x00 }, // !
{ 0x00, 0x00, 0x07, 0x00, 0x07, 0x00 }, // "
{ 0x00, 0x14, 0x7f, 0x14, 0x7f, 0x14 }, // #
{ 0x00, 0x24, 0x2a, 0x7f, 0x2a, 0x12 }, // $
{ 0x00, 0x62, 0x64, 0x08, 0x13, 0x23 }, // %
{ 0x00, 0x36, 0x49, 0x55, 0x22, 0x50 }, // &
{ 0x00, 0x00, 0x05, 0x03, 0x00, 0x00 }, // '
{ 0x00, 0x00, 0x1c, 0x22, 0x41, 0x00 }, // (
{ 0x00, 0x00, 0x41, 0x22, 0x1c, 0x00 }, // )
{ 0x00, 0x14, 0x08, 0x3E, 0x08, 0x14 }, // *
{ 0x00, 0x08, 0x08, 0x3E, 0x08, 0x08 }, // +
{ 0x00, 0x00, 0x00, 0xA0, 0x60, 0x00 }, // ,
{ 0x00, 0x08, 0x08, 0x08, 0x08, 0x08 }, // -
{ 0x00, 0x00, 0x60, 0x60, 0x00, 0x00 }, // .
{ 0x00, 0x20, 0x10, 0x08, 0x04, 0x02 }, // /
{ 0x00, 0x3E, 0x51, 0x49, 0x45, 0x3E }, // 0
{ 0x00, 0x00, 0x42, 0x7F, 0x40, 0x00 }, // 1
{ 0x00, 0x42, 0x61, 0x51, 0x49, 0x46 }, // 2
{ 0x00, 0x21, 0x41, 0x45, 0x4B, 0x31 }, // 3
{ 0x00, 0x18, 0x14, 0x12, 0x7F, 0x10 }, // 4
{ 0x00, 0x27, 0x45, 0x45, 0x45, 0x39 }, // 5
{ 0x00, 0x3C, 0x4A, 0x49, 0x49, 0x30 }, // 6
{ 0x00, 0x01, 0x71, 0x09, 0x05, 0x03 }, // 7
{ 0x00, 0x36, 0x49, 0x49, 0x49, 0x36 }, // 8
{ 0x00, 0x06, 0x49, 0x49, 0x29, 0x1E }, // 9
{ 0x00, 0x00, 0x36, 0x36, 0x00, 0x00 }, // :
{ 0x00, 0x00, 0x56, 0x36, 0x00, 0x00 }, // ;
{ 0x00, 0x08, 0x14, 0x22, 0x41, 0x00 }, // <
{ 0x00, 0x14, 0x14, 0x14, 0x14, 0x14 }, // =
{ 0x00, 0x00, 0x41, 0x22, 0x14, 0x08 }, // >
{ 0x00, 0x02, 0x01, 0x51, 0x09, 0x06 }, // ?
{ 0x00, 0x32, 0x49, 0x59, 0x51, 0x3E }, // @
{ 0x00, 0x7C, 0x12, 0x11, 0x12, 0x7C }, // A
{ 0x00, 0x7F, 0x49, 0x49, 0x49, 0x36 }, // B
{ 0x00, 0x3E, 0x41, 0x41, 0x41, 0x22 }, // C
{ 0x00, 0x7F, 0x41, 0x41, 0x22, 0x1C }, // D
{ 0x00, 0x7F, 0x49, 0x49, 0x49, 0x41 }, // E
{ 0x00, 0x7F, 0x09, 0x09, 0x09, 0x01 }, // F
{ 0x00, 0x3E, 0x41, 0x49, 0x49, 0x7A }, // G
{ 0x00, 0x7F, 0x08, 0x08, 0x08, 0x7F }, // H
{ 0x00, 0x00, 0x41, 0x7F, 0x41, 0x00 }, // I
{ 0x00, 0x20, 0x40, 0x41, 0x3F, 0x01 }, // J
{ 0x00, 0x7F, 0x08, 0x14, 0x22, 0x41 }, // K
{ 0x00, 0x7F, 0x40, 0x40, 0x40, 0x40 }, // L
{ 0x00, 0x7F, 0x02, 0x0C, 0x02, 0x7F }, // M
{ 0x00, 0x7F, 0x04, 0x08, 0x10, 0x7F }, // N
{ 0x00, 0x3E, 0x41, 0x41, 0x41, 0x3E }, // O
{ 0x00, 0x7F, 0x09, 0x09, 0x09, 0x06 }, // P
{ 0x00, 0x3E, 0x41, 0x51, 0x21, 0x5E }, // Q
{ 0x00, 0x7F, 0x09, 0x19, 0x29, 0x46 }, // R
{ 0x00, 0x46, 0x49, 0x49, 0x49, 0x31 }, // S
{ 0x00, 0x01, 0x01, 0x7F, 0x01, 0x01 }, // T
{ 0x00, 0x3F, 0x40, 0x40, 0x40, 0x3F }, // U
{ 0x00, 0x1F, 0x20, 0x40, 0x20, 0x1F }, // V
{ 0x00, 0x3F, 0x40, 0x38, 0x40, 0x3F }, // W
{ 0x00, 0x63, 0x14, 0x08, 0x14, 0x63 }, // X
{ 0x00, 0x07, 0x08, 0x70, 0x08, 0x07 }, // Y
{ 0x00, 0x61, 0x51, 0x49, 0x45, 0x43 }, // Z
{ 0x00, 0x00, 0x7F, 0x41, 0x41, 0x00 }, // [
{ 0x00, 0x55, 0x2A, 0x55, 0x2A, 0x55 }, /* \ */
{ 0x00, 0x00, 0x41, 0x41, 0x7F, 0x00 }, // ]
{ 0x00, 0x04, 0x02, 0x01, 0x02, 0x04 }, // ^
{ 0x00, 0x40, 0x40, 0x40, 0x40, 0x40 }, // _
{ 0x00, 0x00, 0x01, 0x02, 0x04, 0x00 }, // '
{ 0x00, 0x20, 0x54, 0x54, 0x54, 0x78 }, // a
{ 0x00, 0x7F, 0x48, 0x44, 0x44, 0x38 }, // b
{ 0x00, 0x38, 0x44, 0x44, 0x44, 0x20 }, // c
{ 0x00, 0x38, 0x44, 0x44, 0x48, 0x7F }, // d
{ 0x00, 0x38, 0x54, 0x54, 0x54, 0x18 }, // e
{ 0x00, 0x08, 0x7E, 0x09, 0x01, 0x02 }, // f
{ 0x00, 0x18, 0xA4, 0xA4, 0xA4, 0x7C }, // g
{ 0x00, 0x7F, 0x08, 0x04, 0x04, 0x78 }, // h
{ 0x00, 0x00, 0x44, 0x7D, 0x40, 0x00 }, // i
{ 0x00, 0x40, 0x80, 0x84, 0x7D, 0x00 }, // j
{ 0x00, 0x7F, 0x10, 0x28, 0x44, 0x00 }, // k
{ 0x00, 0x00, 0x41, 0x7F, 0x40, 0x00 }, // l
{ 0x00, 0x7C, 0x04, 0x18, 0x04, 0x78 }, // m
{ 0x00, 0x7C, 0x08, 0x04, 0x04, 0x78 }, // n
{ 0x00, 0x38, 0x44, 0x44, 0x44, 0x38 }, // o
{ 0x00, 0xFC, 0x24, 0x24, 0x24, 0x18 }, // p
{ 0x00, 0x18, 0x24, 0x24, 0x18, 0xFC }, // q
{ 0x00, 0x7C, 0x08, 0x04, 0x04, 0x08 }, // r
{ 0x00, 0x48, 0x54, 0x54, 0x54, 0x20 }, // s
{ 0x00, 0x04, 0x3F, 0x44, 0x40, 0x20 }, // t
{ 0x00, 0x3C, 0x40, 0x40, 0x20, 0x7C }, // u
{ 0x00, 0x1C, 0x20, 0x40, 0x20, 0x1C }, // v
{ 0x00, 0x3C, 0x40, 0x30, 0x40, 0x3C }, // w
{ 0x00, 0x44, 0x28, 0x10, 0x28, 0x44 }, // x
{ 0x00, 0x1C, 0xA0, 0xA0, 0xA0, 0x7C }, // y
{ 0x00, 0x44, 0x64, 0x54, 0x4C, 0x44 }, // z
{ 0x14, 0x14, 0x14, 0x14, 0x14, 0x14 }, // horiz lines
};
/****************************************8*16的点阵************************************/
// 取模方式：纵向8点下高位
// 采用一维数组，每个字符对应16个数组元素
// 每16个数组元素的前8个表示字符的上半部分（8*8点阵），后8个表示字符的下半部分（8*8点阵），一共8列16行
static const unsigned char F8X16[]=
{
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,//空格 0
0x00,0x00,0x00,0xF8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x33,0x30,0x00,0x00,0x00,//! 1
0x00,0x10,0x0C,0x06,0x10,0x0C,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,//" 2
0x40,0xC0,0x78,0x40,0xC0,0x78,0x40,0x00,0x04,0x3F,0x04,0x04,0x3F,0x04,0x04,0x00,//# 3
0x00,0x70,0x88,0xFC,0x08,0x30,0x00,0x00,0x00,0x18,0x20,0xFF,0x21,0x1E,0x00,0x00,//$ 4
0xF0,0x08,0xF0,0x00,0xE0,0x18,0x00,0x00,0x00,0x21,0x1C,0x03,0x1E,0x21,0x1E,0x00,//% 5
0x00,0xF0,0x08,0x88,0x70,0x00,0x00,0x00,0x1E,0x21,0x23,0x24,0x19,0x27,0x21,0x10,//& 6
0x10,0x16,0x0E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,//' 7
0x00,0x00,0x00,0xE0,0x18,0x04,0x02,0x00,0x00,0x00,0x00,0x07,0x18,0x20,0x40,0x00,//( 8
0x00,0x02,0x04,0x18,0xE0,0x00,0x00,0x00,0x00,0x40,0x20,0x18,0x07,0x00,0x00,0x00,//) 9
0x40,0x40,0x80,0xF0,0x80,0x40,0x40,0x00,0x02,0x02,0x01,0x0F,0x01,0x02,0x02,0x00,//* 10
0x00,0x00,0x00,0xF0,0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x1F,0x01,0x01,0x01,0x00,//+ 11
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0xB0,0x70,0x00,0x00,0x00,0x00,0x00,//, 12
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,//- 13
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x30,0x30,0x00,0x00,0x00,0x00,0x00,//. 14
0x00,0x00,0x00,0x00,0x80,0x60,0x18,0x04,0x00,0x60,0x18,0x06,0x01,0x00,0x00,0x00,/// 15
0x00,0xE0,0x10,0x08,0x08,0x10,0xE0,0x00,0x00,0x0F,0x10,0x20,0x20,0x10,0x0F,0x00,//0 16
0x00,0x10,0x10,0xF8,0x00,0x00,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,//1 17
0x00,0x70,0x08,0x08,0x08,0x88,0x70,0x00,0x00,0x30,0x28,0x24,0x22,0x21,0x30,0x00,//2 18
0x00,0x30,0x08,0x88,0x88,0x48,0x30,0x00,0x00,0x18,0x20,0x20,0x20,0x11,0x0E,0x00,//3 19
0x00,0x00,0xC0,0x20,0x10,0xF8,0x00,0x00,0x00,0x07,0x04,0x24,0x24,0x3F,0x24,0x00,//4 20
0x00,0xF8,0x08,0x88,0x88,0x08,0x08,0x00,0x00,0x19,0x21,0x20,0x20,0x11,0x0E,0x00,//5 21
0x00,0xE0,0x10,0x88,0x88,0x18,0x00,0x00,0x00,0x0F,0x11,0x20,0x20,0x11,0x0E,0x00,//6 22
0x00,0x38,0x08,0x08,0xC8,0x38,0x08,0x00,0x00,0x00,0x00,0x3F,0x00,0x00,0x00,0x00,//7 23
0x00,0x70,0x88,0x08,0x08,0x88,0x70,0x00,0x00,0x1C,0x22,0x21,0x21,0x22,0x1C,0x00,//8 24
0x00,0xE0,0x10,0x08,0x08,0x10,0xE0,0x00,0x00,0x00,0x31,0x22,0x22,0x11,0x0F,0x00,//9 25
0x00,0x00,0x00,0xC0,0xC0,0x00,0x00,0x00,0x00,0x00,0x00,0x30,0x30,0x00,0x00,0x00,//: 26
0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x60,0x00,0x00,0x00,0x00,//; 27
0x00,0x00,0x80,0x40,0x20,0x10,0x08,0x00,0x00,0x01,0x02,0x04,0x08,0x10,0x20,0x00,//< 28
0x40,0x40,0x40,0x40,0x40,0x40,0x40,0x00,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x00,//= 29
0x00,0x08,0x10,0x20,0x40,0x80,0x00,0x00,0x00,0x20,0x10,0x08,0x04,0x02,0x01,0x00,//> 30
0x00,0x70,0x48,0x08,0x08,0x08,0xF0,0x00,0x00,0x00,0x00,0x30,0x36,0x01,0x00,0x00,//? 31
0xC0,0x30,0xC8,0x28,0xE8,0x10,0xE0,0x00,0x07,0x18,0x27,0x24,0x23,0x14,0x0B,0x00,//@ 32
0x00,0x00,0xC0,0x38,0xE0,0x00,0x00,0x00,0x20,0x3C,0x23,0x02,0x02,0x27,0x38,0x20,//A 33
0x08,0xF8,0x88,0x88,0x88,0x70,0x00,0x00,0x20,0x3F,0x20,0x20,0x20,0x11,0x0E,0x00,//B 34
0xC0,0x30,0x08,0x08,0x08,0x08,0x38,0x00,0x07,0x18,0x20,0x20,0x20,0x10,0x08,0x00,//C 35
0x08,0xF8,0x08,0x08,0x08,0x10,0xE0,0x00,0x20,0x3F,0x20,0x20,0x20,0x10,0x0F,0x00,//D 36
0x08,0xF8,0x88,0x88,0xE8,0x08,0x10,0x00,0x20,0x3F,0x20,0x20,0x23,0x20,0x18,0x00,//E 37
0x08,0xF8,0x88,0x88,0xE8,0x08,0x10,0x00,0x20,0x3F,0x20,0x00,0x03,0x00,0x00,0x00,//F 38
0xC0,0x30,0x08,0x08,0x08,0x38,0x00,0x00,0x07,0x18,0x20,0x20,0x22,0x1E,0x02,0x00,//G 39
0x08,0xF8,0x08,0x00,0x00,0x08,0xF8,0x08,0x20,0x3F,0x21,0x01,0x01,0x21,0x3F,0x20,//H 40
0x00,0x08,0x08,0xF8,0x08,0x08,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,//I 41
0x00,0x00,0x08,0x08,0xF8,0x08,0x08,0x00,0xC0,0x80,0x80,0x80,0x7F,0x00,0x00,0x00,//J 42
0x08,0xF8,0x88,0xC0,0x28,0x18,0x08,0x00,0x20,0x3F,0x20,0x01,0x26,0x38,0x20,0x00,//K 43
0x08,0xF8,0x08,0x00,0x00,0x00,0x00,0x00,0x20,0x3F,0x20,0x20,0x20,0x20,0x30,0x00,//L 44
0x08,0xF8,0xF8,0x00,0xF8,0xF8,0x08,0x00,0x20,0x3F,0x00,0x3F,0x00,0x3F,0x20,0x00,//M 45
0x08,0xF8,0x30,0xC0,0x00,0x08,0xF8,0x08,0x20,0x3F,0x20,0x00,0x07,0x18,0x3F,0x00,//N 46
0xE0,0x10,0x08,0x08,0x08,0x10,0xE0,0x00,0x0F,0x10,0x20,0x20,0x20,0x10,0x0F,0x00,//O 47
0x08,0xF8,0x08,0x08,0x08,0x08,0xF0,0x00,0x20,0x3F,0x21,0x01,0x01,0x01,0x00,0x00,//P 48
0xE0,0x10,0x08,0x08,0x08,0x10,0xE0,0x00,0x0F,0x18,0x24,0x24,0x38,0x50,0x4F,0x00,//Q 49
0x08,0xF8,0x88,0x88,0x88,0x88,0x70,0x00,0x20,0x3F,0x20,0x00,0x03,0x0C,0x30,0x20,//R 50
0x00,0x70,0x88,0x08,0x08,0x08,0x38,0x00,0x00,0x38,0x20,0x21,0x21,0x22,0x1C,0x00,//S 51
0x18,0x08,0x08,0xF8,0x08,0x08,0x18,0x00,0x00,0x00,0x20,0x3F,0x20,0x00,0x00,0x00,//T 52
0x08,0xF8,0x08,0x00,0x00,0x08,0xF8,0x08,0x00,0x1F,0x20,0x20,0x20,0x20,0x1F,0x00,//U 53
0x08,0x78,0x88,0x00,0x00,0xC8,0x38,0x08,0x00,0x00,0x07,0x38,0x0E,0x01,0x00,0x00,//V 54
0xF8,0x08,0x00,0xF8,0x00,0x08,0xF8,0x00,0x03,0x3C,0x07,0x00,0x07,0x3C,0x03,0x00,//W 55
0x08,0x18,0x68,0x80,0x80,0x68,0x18,0x08,0x20,0x30,0x2C,0x03,0x03,0x2C,0x30,0x20,//X 56
0x08,0x38,0xC8,0x00,0xC8,0x38,0x08,0x00,0x00,0x00,0x20,0x3F,0x20,0x00,0x00,0x00,//Y 57
0x10,0x08,0x08,0x08,0xC8,0x38,0x08,0x00,0x20,0x38,0x26,0x21,0x20,0x20,0x18,0x00,//Z 58
0x00,0x00,0x00,0xFE,0x02,0x02,0x02,0x00,0x00,0x00,0x00,0x7F,0x40,0x40,0x40,0x00,//[ 59
0x00,0x0C,0x30,0xC0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x06,0x38,0xC0,0x00,//\ 60
0x00,0x02,0x02,0x02,0xFE,0x00,0x00,0x00,0x00,0x40,0x40,0x40,0x7F,0x00,0x00,0x00,//] 61
0x00,0x00,0x04,0x02,0x02,0x02,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,//^ 62
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,//_ 63
0x00,0x02,0x02,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,//` 64
0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x00,0x19,0x24,0x22,0x22,0x22,0x3F,0x20,//a 65
0x08,0xF8,0x00,0x80,0x80,0x00,0x00,0x00,0x00,0x3F,0x11,0x20,0x20,0x11,0x0E,0x00,//b 66
0x00,0x00,0x00,0x80,0x80,0x80,0x00,0x00,0x00,0x0E,0x11,0x20,0x20,0x20,0x11,0x00,//c 67
0x00,0x00,0x00,0x80,0x80,0x88,0xF8,0x00,0x00,0x0E,0x11,0x20,0x20,0x10,0x3F,0x20,//d 68
0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x00,0x1F,0x22,0x22,0x22,0x22,0x13,0x00,//e 69
0x00,0x80,0x80,0xF0,0x88,0x88,0x88,0x18,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,//f 70
0x00,0x00,0x80,0x80,0x80,0x80,0x80,0x00,0x00,0x6B,0x94,0x94,0x94,0x93,0x60,0x00,//g 71
0x08,0xF8,0x00,0x80,0x80,0x80,0x00,0x00,0x20,0x3F,0x21,0x00,0x00,0x20,0x3F,0x20,//h 72
0x00,0x80,0x98,0x98,0x00,0x00,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,//i 73
0x00,0x00,0x00,0x80,0x98,0x98,0x00,0x00,0x00,0xC0,0x80,0x80,0x80,0x7F,0x00,0x00,//j 74
0x08,0xF8,0x00,0x00,0x80,0x80,0x80,0x00,0x20,0x3F,0x24,0x02,0x2D,0x30,0x20,0x00,//k 75
0x00,0x08,0x08,0xF8,0x00,0x00,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,//l 76
0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x00,0x20,0x3F,0x20,0x00,0x3F,0x20,0x00,0x3F,//m 77
0x80,0x80,0x00,0x80,0x80,0x80,0x00,0x00,0x20,0x3F,0x21,0x00,0x00,0x20,0x3F,0x20,//n 78
0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x00,0x1F,0x20,0x20,0x20,0x20,0x1F,0x00,//o 79
0x80,0x80,0x00,0x80,0x80,0x00,0x00,0x00,0x80,0xFF,0xA1,0x20,0x20,0x11,0x0E,0x00,//p 80
0x00,0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x0E,0x11,0x20,0x20,0xA0,0xFF,0x80,//q 81
0x80,0x80,0x80,0x00,0x80,0x80,0x80,0x00,0x20,0x20,0x3F,0x21,0x20,0x00,0x01,0x00,//r 82
0x00,0x00,0x80,0x80,0x80,0x80,0x80,0x00,0x00,0x33,0x24,0x24,0x24,0x24,0x19,0x00,//s 83
0x00,0x80,0x80,0xE0,0x80,0x80,0x00,0x00,0x00,0x00,0x00,0x1F,0x20,0x20,0x00,0x00,//t 84
0x80,0x80,0x00,0x00,0x00,0x80,0x80,0x00,0x00,0x1F,0x20,0x20,0x20,0x10,0x3F,0x20,//u 85
0x80,0x80,0x80,0x00,0x00,0x80,0x80,0x80,0x00,0x01,0x0E,0x30,0x08,0x06,0x01,0x00,//v 86
0x80,0x80,0x00,0x80,0x00,0x80,0x80,0x80,0x0F,0x30,0x0C,0x03,0x0C,0x30,0x0F,0x00,//w 87
0x00,0x80,0x80,0x00,0x80,0x80,0x80,0x00,0x00,0x20,0x31,0x2E,0x0E,0x31,0x20,0x00,//x 88
0x80,0x80,0x80,0x00,0x00,0x80,0x80,0x80,0x80,0x81,0x8E,0x70,0x18,0x06,0x01,0x00,//y 89
0x00,0x80,0x80,0x80,0x80,0x80,0x80,0x00,0x00,0x21,0x30,0x2C,0x22,0x21,0x30,0x00,//z 90
0x00,0x00,0x00,0x00,0x80,0x7C,0x02,0x02,0x00,0x00,0x00,0x00,0x00,0x3F,0x40,0x40,//{ 91
0x00,0x00,0x00,0x00,0xFF,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0x00,0x00,0x00,//| 92
0x00,0x02,0x02,0x7C,0x80,0x00,0x00,0x00,0x00,0x40,0x40,0x3F,0x00,0x00,0x00,0x00,//} 93
0x00,0x06,0x01,0x01,0x02,0x02,0x04,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,//~ 94
};
#endif
oled.h
C
#ifndef OLED_H
#define OLED_H
typedef enum {
FONT6x8 = 1,
FONT8x16,
}Font;
uint32_t OledInit(void);
void OledSetPosition(uint8_t x, uint8_t y);
void OledFillScreen(uint8_t data);
void OledShowChar(uint8_t x, uint8_t y, uint8_t ch, Font font);
void OledShowString(uint8_t x, uint8_t y, const char *str, Font font);
#endif // OLED_H
oled.c
C
#include <stdio.h>
#include <stdint.h>
#include "iot_gpio.h"
#include "iot_i2c.h"
#include "iot_errno.h"
#include "hi_io.h"
#include "oled_fonts.h"
#include "oled.h"
// 从机地址(最低位补零后)
#define OLED_SLAVE_ADDR 0x78
// I2C设备ID，即使用I2C1
#define OLED_I2C1_ID 1
// I2C1引脚
#define OLED_I2C1_SDA 0
#define OLED_I2C1_SCL 1
// I2C1的波特率，即传输速率 400kHZ
#define OLED_I2C1_BAUDRATE (400 * 1000)
// 控制字节-写命令
#define OLED_CTR_CMD 0x00
// 控制字节-写数据
#define OLED_CTR_DATA 0x40
// 计算数组长度
#define ARRAY_SIZE(a) sizeof(a) / sizeof(a[0])
/* 存储发送和接收的数据 */
typedef struct
{
// 要发送的数据的指针
unsigned char *sendBuf;
// 要发送的数据长度
unsigned int sendLen;
// 要接收的数据的指针
unsigned char *receiveBuf;
// 要接收的数据长度
unsigned int receiveLen;
} IotI2cData;
/**
* @brief 指定内存地址写入一个字节命令/数据
* @param memAddr 内存地址，可以选择写入命令 0x00 或写入数据 0x40 模式
* @param byte 需要写入的命令/数据
* @retval 成功返回 IOT_SUCCESS，失败返回 IOT_FAILURE
*/
static uint32_t I2cMemWriteByte(uint8_t memAddr, uint8_t byte)
{
/* 定义发送的 */
uint8_t buffer[] = {memAddr, byte};
IotI2cData i2cData = {0};
/* 用结构体处理发送数据 */
i2cData.sendBuf = buffer;
i2cData.sendLen = sizeof(buffer) / sizeof(buffer[0]);
return IoTI2cWrite(OLED_I2C1_ID, OLED_SLAVE_ADDR, i2cData.sendBuf, i2cData.sendLen);
}
/**
* @brief 写一个字节命令
* @param cmd 需写入的命令
* @retval 成功返回 IOT_SUCCESS，失败返回 IOT_FAILURE
*/
static uint32_t WriteCmd(uint8_t cmd)
{
return I2cMemWriteByte(OLED_CTR_CMD, cmd);
}
/**
* @brief 写一个字节数据
* @param data 需写入的数据
* @retval 成功返回 IOT_SUCCESS，失败返回 IOT_FAILURE
*/
static uint32_t WriteData(uint8_t data)
{
return I2cMemWriteByte(OLED_CTR_DATA, data);
}
/**
* @brief 初始化OLED
*/
uint32_t OledInit(void)
{
static const uint8_t initCmds[] = {
0xAE, // 显示关闭
0x00, // 页寻址模式时，设置列地址的低4位为0000
0x10, // 页寻址模式时，设置列地址的高4位为0000
0x40, // 设置起始行地址为第0行
0xB0, // 页寻址模式时，设置页面起始地址为PAGE0
0x81, // 设置对比度
0xFF, // 对比度数值
0xA1, // set segment remap
0xA6, // 设置正常显示。0对应像素熄灭，1对应像素亮起
0xA8, // --set multiplex ratio(1 to 64)
0x3F, // --1/32 duty
0xC8, // Com scan direction
0xD3, // -set display offset
0x00, //
0xD5, // set osc division
0x80, //
0xD8, // set area color mode off
0x05, //
0xD9, // Set Pre-Charge Period
0xF1, //
0xDA, // set com pin configuartion
0x12, //
0xDB, // set Vcomh
0x30, //
0x8D, // set charge pump enable
0x14, //
0xAF, // 显示开启
};
/* 初始化I2C的GPIO引脚 */
IoTGpioInit(OLED_I2C1_SDA);
hi_io_set_func(OLED_I2C1_SDA, HI_IO_FUNC_GPIO_0_I2C1_SDA);
IoTGpioInit(OLED_I2C1_SCL);
hi_io_set_func(OLED_I2C1_SCL, HI_IO_FUNC_GPIO_1_I2C1_SCL);
/* 初始化I2C1的波特率 */
IoTI2cInit(OLED_I2C1_ID, OLED_I2C1_BAUDRATE);
/* 发送初始化命令 */
for (int i=0 ; i < ARRAY_SIZE(initCmds) ; i++) {
uint32_t status = WriteCmd(initCmds[i]);
if (status != IOT_SUCCESS) {
return status;
}
}
return IOT_SUCCESS;
}
/**
* @brief 设置显示的起始位置
* @param x: 横坐标，取值范围是0~127，对应128个像素点，单位为1bit。
* @param y: 纵坐标，取值范围是0~7，对应8个pages，单位是字节(8bits)。
*/
void OledSetPosition(uint8_t x, uint8_t y)
{
/* 起始页(y坐标) */
WriteCmd(0xB0 + y);
/* 列地址低四位 */
WriteCmd(0x0F & x);
/* 列地址高四位 */
WriteCmd(0x10 | ((0xF0 & x) >> 4));
}
/**
* @brief 全屏填充，即按128列数据一致的方式填充
* @param data 填充的1字节数据
*/
void OledFillScreen(uint8_t data)
{
uint8_t m=0;
uint8_t n=0;
/* 遍历8个page，一个page有8像素点 */
for (m=0 ; m < 8 ; m++) {
// 设置page地址：0~7
WriteCmd(0xB0 + m);
// 设置显示位置为第0列
WriteCmd(0x00);
WriteCmd(0x10);
// 遍历128列
for (n=0 ; n < 128 ; n++) {
WriteData(data);
}
}
}
/**
* @brief 显示一个字符
* @param x: x坐标，1像素为单位
* @param y: y坐标，8像素为单位
* @param ch: 要显示的字符
* @param font: 字库
*/
void OledShowChar(uint8_t x, uint8_t y, uint8_t ch, Font font)
{
/* 字库数组下标 */
uint8_t c;
/* 循环计数 */
uint8_t i = 0;
/* 空格的ASCII码十进制数为32,(字符-32)即为其在字库数组的下标 */
c = ch - ' ';
/* 区分字体大小, FONT8x16需分两个pages */
if (font == FONT8x16) {
// 定位
OledSetPosition(x, y);
// 写第一个page
for (i=0 ; i < 8 ; i++) {
WriteData(F8X16[c*16 + i]);
}
// 重新定位
OledSetPosition(x, y + 1);
// 写第二个page
for (i=0 ; i < 8 ; i++) {
WriteData(F8X16[c * 16 + i + 8]);
}
}
/* FONT6x8,一个page足矣 */
else {
// 定位
OledSetPosition(x, y);
// 写一个page
for (i=0 ; i < 6 ; i++) {
WriteData(F6x8[c][i]);
}
}
}
/**
* @brief 显示字符串
*
*/
void OledShowString(uint8_t x, uint8_t y, const char *str, Font font)
{
/* 字符数组（字符串）下标 */
uint8_t j = 0;
if (str == NULL)
{
printf("[ERROR] param is NULL,Please check!!!\r\n");
return;
}
while (str[j])
{
// 显示一个字符
OledShowChar(x, y, str[j], font);
// 设置字符间距
x += 8;
// 如果下一个要显示的字符超出了OLED显示的范围，则换行
if (x > 120) {
x = 0;
y += 2;
}
// 下一个字符
j++;
}
}
7.3.2 OLED使用示例¶
C
#include <stdio.h>
#include <stdint.h>
#include "ohos_init.h"
#include "cmsis_os2.h"
#include "oled.h"
/**
* oled_demo/oled_demo.c
* OLED案例分析
* 使用自己编写的各个OLED驱动显示字符
*/
static void OledTask(void* params)
{
/* 初始化 */
OledInit();
OledFillScreen(0x00);
/* FONT6x8 */
OledShowChar(0, 0, 'A', FONT6x8);
OledShowChar(0, 1, 'B', FONT6x8);
OledShowChar(0, 2, 'C', FONT6x8);
OledShowChar(0, 3, 'D', FONT6x8);
OledShowChar(0, 4, 'E', FONT6x8);
OledShowChar(0, 5, 'F', FONT6x8);
OledShowChar(0, 6, 'G', FONT6x8);
OledShowChar(0, 7, 'H', FONT6x8);
/* FONT8x16 */
OledShowChar(8, 0, 'I', FONT8x16);
OledShowChar(8, 2, 'J', FONT8x16);
OledShowChar(8, 4, 'K', FONT8x16);
OledShowChar(8, 6, 'L', FONT8x16);
/* 字符串 */
OledShowString(16, 0, "OpenHarmony", FONT8x16);
while(1)
{
osDelay(10);
}
}
static void OledEntry(void)
{
osThreadAttr_t attr = {
.name = "OledThread",
.stack_size = 1024,
.priority = osPriorityNormal
};
if (osThreadNew(OledTask, NULL, &attr) == NULL) {
printf("[ERROR] Thread Create Faild.\r\n");
} else {
printf("[INFO] Thread Create Success.\r\n");
}
}
SYS_RUN(OledEntry);
模块编译脚本
Text Only
static_library ("oled_demo") {
sources = [
"oled.c",
"oled_demo.c",
]
include_dirs = [
# include "ohos_init.h"
"//utils/native/lite/include",
# include CMSIS-RTOS API V2 for OpenHarmony1.0+
"//kernel/liteos_m/kal/cmsis",
# include IoT硬件设备操作接口 for OpenHarmony1.0+：
"//base/iot_hardware/peripheral/interfaces/kits",
]
}
APP编译脚本
C
import("//build/lite/config/component/lite_component.gni")
lite_component("app") {
features = [
"gn_practice/application:gn_app",
"gn_practice/driver:gn_driver",
"gn_practice/library:gn_library",
"kv_store_demo:kv_store_demo",
"file_demo:file_demo",
"thread_demo:thread_demo",
"timer_demo:timer_demo",
"mutex_demo:mutex_demo",
# GPIO模块
"gpio_demo:gpio_demo",
# ADC模块
"adc_demo:adc_demo",
# OLED模块
"oled_demo:oled_demo",
]
}