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I2C总线是我们开发过程中经常使用的一种串行总线。 I2C主要功能特点包括： 1、只需要两条总线； 2、所有组件之间都存在简单的主/从关系，连接到总线的每个设备均可通过唯一地址进行软件寻址； 3、是真正的多主设备总线，可提供仲裁和冲突检测； 4、最大从机数：理论上是127； 5、传输速度： 标准模式：Standard Mode = 100 Kbps 快速模式：Fast Mode = 400 Kbps 高速模式：High speed mode = 3.4 Mbps 超快速模式：Ultra fast mode = 5 Mbps I2C总线协议详解可参考以下资料：
UM10204_I2C-bus specification and user manual-Rev.7.0.pdf
(733.36 KB)
I2C总线规范.pdf
(918.13 KB)
此篇主要介绍GPIO软件模拟实现I2C来驱动0.96寸OLED显示屏，OLED显示屏资料：
0.96寸OLED使用文档V3.0.pdf
(1.68 MB)
硬件连接 GND —— GND VCC —— 3.3V SCL —— PA1 SDA —— PA2 软件代码 I2C代码： //设置SDA输入模式
void SDA_IN(void)
{
GPIO_InitTypeDef gpio_init_struct;
//根据GPIO组初始化GPIO时钟
RCC_AHBPeriphClk_Enable(SCL_GPIO_CRM_CLK, ENABLE);
gpio_init_struct.IT = GPIO_IT_NONE;
gpio_init_struct.Mode = GPIO_MODE_INPUT_PULLUP;
gpio_init_struct.Pins = SDA_PIN;
gpio_init_struct.Speed = GPIO_SPEED_HIGH;
GPIO_Init(SDA_GPIO, &gpio_init_struct);
}
//设置SDA为输出模式
void SDA_OUT(void)
{
GPIO_InitTypeDef gpio_init_struct;
//根据GPIO组初始化GPIO时钟
RCC_AHBPeriphClk_Enable(SDA_GPIO_CRM_CLK, ENABLE);
gpio_init_struct.IT = GPIO_IT_NONE;
gpio_init_struct.Mode = GPIO_MODE_OUTPUT_PP;
gpio_init_struct.Pins = SDA_PIN;
gpio_init_struct.Speed = GPIO_SPEED_HIGH;
GPIO_Init(SDA_GPIO, &gpio_init_struct);
}
//设置SCL电平
void I2C_SCL(int n)
{
if(n == 1)
{
GPIO_WritePin(SCL_GPIO, SCL_PIN, GPIO_Pin_SET); //设置SCL为高电平
}
else
{
GPIO_WritePin(SCL_GPIO, SCL_PIN, GPIO_Pin_RESET); //设置SCL为低电平
}
}
//设置SDA电平
void I2C_SDA(int n)
{
if(n == 1)
{
GPIO_WritePin(SDA_GPIO, SDA_PIN, GPIO_Pin_SET); //设置SDA为高电平
}
else
{
GPIO_WritePin(SDA_GPIO, SDA_PIN, GPIO_Pin_RESET); //设置SDA为低电平
}
}
//读取SDA电平
unsigned char READ_SDA(void)
{
return GPIO_ReadPin(SDA_GPIO, SDA_PIN); //读取SDA电平
}
//I2C初始化
void I2C_Init(void)
{
GPIO_InitTypeDef gpio_init_struct;
//根据GPIO组初始化GPIO时钟
RCC_AHBPeriphClk_Enable(SCL_GPIO_CRM_CLK | SDA_GPIO_CRM_CLK, ENABLE);
//GPIO_SCL初始化设置
gpio_init_struct.IT = GPIO_IT_NONE;
gpio_init_struct.Mode = GPIO_MODE_OUTPUT_PP;
gpio_init_struct.Pins = SCL_PIN;
gpio_init_struct.Speed = GPIO_SPEED_HIGH;
GPIO_Init(SCL_GPIO, &gpio_init_struct);
//GPIO_SDA初始化设置
gpio_init_struct.IT = GPIO_IT_NONE;
gpio_init_struct.Mode = GPIO_MODE_OUTPUT_PP;
gpio_init_struct.Pins = SDA_PIN;
gpio_init_struct.Speed = GPIO_SPEED_HIGH;
GPIO_Init(SDA_GPIO, &gpio_init_struct);
//SCL、SDA的初始化均为高电平
I2C_SCL(1);
I2C_SDA(1);
}
//I2C Start
void I2C_Start(void)
{
SDA_OUT();
I2C_SDA(1);
I2C_SCL(1);
//Delay_Us(1);//4
I2C_SDA(0); //START:when CLK is high,DATA change form high to low
//Delay_Us(1);//4
I2C_SCL(0); //钳住I2C总线,准备发送或接收数据
}
//I2C Stop
void I2C_Stop(void)
{
SDA_OUT();
I2C_SCL(0);
I2C_SDA(0); //STOP:when CLK is high DATA change form low to high
//Delay_Us(1);//4
I2C_SCL(1);
I2C_SDA(1); //发送I2C总线结束信号
//Delay_Us(1);//4
}
//I2C_Wait_ack 返回HAL_OK表示wait成功,返回HAL_ERROR表示wait失败
unsigned char I2C_Wait_Ack(void) //IIC_Wait_ack,返回wait失败或是成功
{
unsigned char ucErrTime = 0;
SDA_IN();
I2C_SDA(1);
//Delay_Us(1);
I2C_SCL(1);
//Delay_Us(1);
while(READ_SDA())
{
ucErrTime++;
if(ucErrTime > 250)
{
I2C_Stop();
return HAL_ERROR;
}
}
I2C_SCL(0);
return HAL_OK;
}
//产生ACK应答
void I2C_Ack(void)
{
I2C_SCL(0);
SDA_OUT();
I2C_SDA(0);
//Delay_Us(1);//2
I2C_SCL(1);
//Delay_Us(1);//2
I2C_SCL(0);
}
//产生NACK应答
void I2C_NAck(void)
{
I2C_SCL(0);
SDA_OUT();
I2C_SDA(1);
//Delay_Us(1);//2
I2C_SCL(1);
//Delay_Us(1);//2
I2C_SCL(0);
}
//I2C_Send_Byte,入口参数为要发送的字节
void I2C_Send_Byte(unsigned char txd)
{
unsigned char cnt = 0;
SDA_OUT();
I2C_SCL(0);
for(cnt = 0; cnt < 8; cnt++)
{
I2C_SDA((txd & 0x80) >> 7);
txd <<= 1;
//Delay_Us(2);
I2C_SCL(1);
//Delay_Us(2);
I2C_SCL(0);
//Delay_Us(2);
}
}
//I2C_Read_Byte,入口参数为是否要发送ACK信号
unsigned char I2C_Read_Byte(unsigned char ack)
{
unsigned char cnt, rec = 0;
SDA_IN();
for(cnt = 0; cnt < 8; cnt++)
{
I2C_SCL(0);
//Delay_Us(2);
I2C_SCL(1);
rec <<= 1;
if(READ_SDA())
{
rec++;
}
//Delay_Us(1);
}
if(!ack)
{
I2C_NAck();
}
else
{
I2C_Ack();
}
return rec;
}
OLED代码： //向设备写控制命令
static void OLED_Write_CMD(unsigned char cmd)
{
#ifdef HW_I2C
unsigned char tx_buf[BUF_SIZE] = {0x00, cmd};
I2C_MasterSendDataToSlave(CW_I2C2, tx_buf, BUF_SIZE);
#endif
#ifdef SW_I2C
I2C_Start();
I2C_Send_Byte(0x78);
I2C_Wait_Ack();
I2C_Send_Byte(0x00);
I2C_Wait_Ack();
I2C_Send_Byte(cmd);
I2C_Wait_Ack();
I2C_Stop();
#endif
#ifdef HW_SPI
OLED_CS_LOW;
OLED_DC_LOW;
while (SPI_GetFlagStatus(SPI_MASTER, SPI_FLAG_TXE) == RESET);
SPI_SendData(SPI_MASTER, cmd);
while (SPI_GetFlagStatus(SPI_MASTER, SPI_FLAG_RXNE) == RESET);
SPI_ReceiveData(SPI_MASTER);
OLED_CS_HIGH;
#endif
#ifdef SW_SPI
OLED_CS_LOW;
OLED_DC_LOW;
SPI_WriteByte(cmd);
OLED_CS_HIGH;
#endif
}
//向设备写数据
static void OLED_Write_Date(unsigned char date)
{
#ifdef HW_I2C
unsigned char tx_buf[BUF_SIZE] = {0x40, date};
I2C_MasterSendDataToSlave(CW_I2C2, tx_buf, BUF_SIZE);
#endif
#ifdef SW_I2C
I2C_Start();
I2C_Send_Byte(0x78);
I2C_Wait_Ack();
I2C_Send_Byte(0x40);
I2C_Wait_Ack();
I2C_Send_Byte(date);
I2C_Wait_Ack();
I2C_Stop();
#endif
#ifdef HW_SPI
OLED_CS_LOW;
OLED_DC_HIGH;
while (SPI_GetFlagStatus(SPI_MASTER, SPI_FLAG_TXE) == RESET);
SPI_SendData(SPI_MASTER, date);
while (SPI_GetFlagStatus(SPI_MASTER, SPI_FLAG_RXNE) == RESET);
SPI_ReceiveData(SPI_MASTER);
OLED_CS_HIGH;
#endif
#ifdef SW_SPI
OLED_CS_LOW;
OLED_DC_HIGH;
SPI_WriteByte(date);
OLED_CS_HIGH;
#endif
}
//坐标设置
static void OLED_Set_Pos(unsigned char x, unsigned char y)
{
OLED_Write_CMD(0xB0 + y);
OLED_Write_CMD(((x & 0xF0) >> 4) | 0x10);
OLED_Write_CMD(x & 0x0F);
}
//开启OLED显示
static void OLED_Display_On(void)
{
OLED_Write_CMD(0x8D); //SET DCDC命令
OLED_Write_CMD(0x14); //DCDC ON
OLED_Write_CMD(0xAF); //DISPLAY ON
}
//关闭OLED显示
static void OLED_Display_Off(void)
{
OLED_Write_CMD(0x8D); //SET DCDC命令
OLED_Write_CMD(0x10); //DCDC OFF
OLED_Write_CMD(0xAE); //DISPLAY OFF
}
//OLED清屏
void OLED_Clear(void)
{
unsigned char cnt, count;
for(cnt = 0; cnt < 8; cnt++)
{
OLED_Write_CMD(0xB0 + cnt);
OLED_Write_CMD(0x00);
OLED_Write_CMD(0x10);
for(count = 0; count < 128; count++)
{
OLED_Write_Date(0x00);
}
}
}
//OLED清行
void OLED_Clear_Row(unsigned char n)
{
unsigned char count;
OLED_Write_CMD(0xB0 + n);
OLED_Write_CMD(0x00);
OLED_Write_CMD(0x10);
for(count = 0; count < 128; count++)
{
OLED_Write_Date(0x00);
}
}
//OLED填满屏幕
void OLED_Fill(void)
{
unsigned char cnt, count;
for(cnt = 0; cnt < 8; cnt++)
{
OLED_Write_CMD(0xB0 + cnt); //设置页地址（0~7）
OLED_Write_CMD(0x00); //设置显示位置—列低地址
OLED_Write_CMD(0x10); //设置显示位置—列高地址
for(count = 0; count < 128; count++)
{
OLED_Write_Date(0x01);
}
}
}
//指定位置显示一个字符
//x:0~127
//y:0~63
//chr:字符
//mode:0,反白显示;1,正常显示
//size:选择字体 16/12
void OLED_ShowChar(unsigned char x, unsigned char y, unsigned char chr, unsigned char size)
{
unsigned char offset = 0, cnt = 0;
offset = chr - ' '; //计算偏移量
if(x > 128 - 1)
{
x = 0;
y = y + 2;
}
if(size == 16)
{
OLED_Set_Pos(x, y);
for(cnt = 0; cnt < 8; cnt++)
{
OLED_Write_Date(F8x16[offset * 16 + cnt]);
}
OLED_Set_Pos(x, y + 1);
for(cnt = 0; cnt < 8; cnt++)
{
OLED_Write_Date(F8x16[offset * 16 + cnt + 8]);
}
}
else
{
OLED_Set_Pos(x, y);
for(cnt = 0; cnt < 6; cnt++)
{
OLED_Write_Date(F6x8[offset][cnt]);
}
}
}
unsigned int oled_pow(unsigned char m, unsigned char n)
{
unsigned int result = 1;
while(n--)
{
result *= m;
}
return result;
}
//指定位置显示一个数字
//x,y:起点坐标
//num:数值(0~4294967295)
//len:数字的位数
//size:字体大小
//mode:模式 0,填充模式;1,叠加模式
void OLED_ShowNum(unsigned char x, unsigned char y, unsigned int num, unsigned char len, unsigned char size)
{
unsigned char cnt, temp;
unsigned char show = 0;
for(cnt = 0; cnt < len; cnt++)
{
temp = (num / oled_pow(10, len - cnt - 1)) % 10;
if(show == 0 && cnt < (len - 1))
{
if(temp == 0)
{
OLED_ShowChar(x + (size / 2) * cnt, y, ' ', size);
continue;
}
else
{
show = 1;
}
}
OLED_ShowChar(x + (size / 2) * cnt, y, temp + '0', size);
}
}
//指定位置显示字符串
void OLED_ShowString(unsigned char x, unsigned char y, unsigned char *chr, unsigned char size)
{
unsigned char cnt = 0;
while(chr[cnt] != '\0')
{
OLED_ShowChar(x, y, chr[cnt], size);
x += 8;
if(x > 120)
{
x = 0;
y += 2;
}
cnt++;
}
}
//显示汉字
void OLED_ShowCHinese(unsigned char x, unsigned char y, unsigned char no)
{
unsigned char cnt, addr = 0;
OLED_Set_Pos(x, y);
for(cnt = 0; cnt < 16; cnt++)
{
OLED_Write_Date(Hzk[2 * no][cnt]);
addr++;
}
OLED_Set_Pos(x, y + 1);
for(cnt = 0; cnt < 16; cnt++)
{
OLED_Write_Date(Hzk[2 * no + 1][cnt]);
addr++;
}
}
//显示图片
/*
@brief 显示图片
@param x0：起始列地址
y0：起始页地址
x1：终止列地址
y1：终止页地址
BMP[]：存放图片代码的数组
@retval 无
*/
void OLED_DrawBMP(unsigned char x0, unsigned char y0, unsigned char x1, unsigned char y1, unsigned char BMP[])
{
unsigned int j = 0; //定义变量
unsigned char x, y; //定义变量
if(y1 % 8 == 0)
{
y = y1 / 8; //判断终止页是否为8的整数倍
}
else
{
y = y1 / 8 + 1;
}
for(y = y0; y < y1; y++) //从起始页开始，画到终止页
{
OLED_Set_Pos(x0, y); //在页的起始列开始画
for(x = x0; x < x1; x++) //画x1 - x0 列
{
OLED_Write_Date(BMP[j++]); //画图片的点
}
}
}
//显示动图
/*
@brief 显示动图
@param x0：起始列地址
y0：起始页地址
x1：终止列地址
y1：终止页地址
k: 帧个数
m: 单帧数组大小
BMP[][m]：存放动图代码的数组
@retval 无
*/
void OLED_DrawGIF(unsigned char x0, unsigned char y0, unsigned char x1, unsigned char y1, unsigned char k, int m, const unsigned char GIF[][m])
{
unsigned int j = 0; //定义变量
unsigned char x, y, i; //定义变量
if(y1 % 8 == 0)
{
y = y1 / 8; //判断终止页是否为8的整数倍
}
else
{
y = y1 / 8 + 1;
}
for (i = 0; i < k; i++) //从第一帧开始画
{
j = 0;
for(y = y0; y < y1; y++) //从起始页开始，画到终止页
{
OLED_Set_Pos(x0, y); //在页的起始列开始画
for(x = x0; x < x1; x++) //画x1 - x0 列
{
OLED_Write_Date(GIF[i][j++]); //画图片的点
}
}
//Delay_Ms(80);
}
}
#if defined SW_SPI || defined HW_SPI
//SPI驱动方式DC、RES引脚初始化
void OLED_SPI_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
//根据GPIO组初始化GPIO时钟
RCC_AHBPeriphClk_Enable( RCC_OLED_DC | RCC_OLED_RES, ENABLE);
//GPIO_DC初始化设置
GPIO_InitStructure.Pins = PIN_OLED_DC;
GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
GPIO_InitStructure.IT = GPIO_IT_NONE;
GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_Init(PORT_OLED_DC, &GPIO_InitStructure);
//GPIO_RES初始化设置
GPIO_InitStructure.Pins = PIN_OLED_RES;
GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
GPIO_InitStructure.IT = GPIO_IT_NONE;
GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_Init(PORT_OLED_RES, &GPIO_InitStructure);
OLED_RES_LOW;
Delay_Ms(200);
OLED_RES_HIGH;
}
#endif
//OLED初始化
void OLED_Init(void)
{
#ifdef SW_I2C
I2C_Init();
#endif
#ifdef HW_I2C
I2C_Init();
#endif
#ifdef SW_SPI
SPI_Initial();
OLED_SPI_GPIO_Init();
#endif
#ifdef HW_SPI
SPI_Initial();
OLED_SPI_GPIO_Init();
#endif
Delay_Ms(200);
OLED_Write_CMD(0xAE); //display off
OLED_Write_CMD(0x00); //set low column address
OLED_Write_CMD(0x10); //set high column address
OLED_Write_CMD(0x40); //set start line address
OLED_Write_CMD(0xB0); //set page address
OLED_Write_CMD(0x81); //contract control
OLED_Write_CMD(0xFF); //128
OLED_Write_CMD(0xA1); //set segment remap
OLED_Write_CMD(0xA6); //normal / reverse
OLED_Write_CMD(0xA8); //set multiplex ratio(1 to 64)
OLED_Write_CMD(0x3F); //1/32 duty
OLED_Write_CMD(0xC8); //Com scan direction
OLED_Write_CMD(0xD3); //set display offset
OLED_Write_CMD(0x00); //
OLED_Write_CMD(0xD5); //set osc division
OLED_Write_CMD(0x80); //
OLED_Write_CMD(0xD8); //set area color mode off
OLED_Write_CMD(0x05); //
OLED_Write_CMD(0xD9); //Set Pre-Charge Period
OLED_Write_CMD(0xF1); //
OLED_Write_CMD(0xDA); //set com pin configuartion
OLED_Write_CMD(0x12); //
OLED_Write_CMD(0xDB); //set Vcomh
OLED_Write_CMD(0x30); //
OLED_Write_CMD(0x8D); //set charge pump enable
OLED_Write_CMD(0x14); //
OLED_Write_CMD(0xAF); //turn on oled panel
}
运行测试
测试代码
CW32F030CxTx_SW_I2C_OLED.zip
(261.38 KB)
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