[N32L43X评测] 2.模拟I2C驱动OLED

805721366 发表于 2022-7-26 22:27

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：





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：

硬件连接

GND  ——  GND

VCC  ——  3.3V

SCL  ——  PB8

SDA  ——  PB9



软件代码

I2C代码：

<pre>
<code>//设置SDA输入模式
void SDA_IN(void)
{
GPIO_InitType GPIO_InitStructure;

RCC_EnableAPB2PeriphClk( SDA_GPIO_CRM_CLK, ENABLE);

GPIO_InitStruct(&GPIO_InitStructure);
GPIO_InitStructure.Pin = SDA_PIN;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_Slew_Rate_High;
GPIO_InitStructure.GPIO_Current = GPIO_DC_4mA;
GPIO_InitStructure.GPIO_Pull = GPIO_Pull_Up;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Input;
GPIO_InitPeripheral(SDA_GPIO, &GPIO_InitStructure);
}

//设置SDA为输出模式
void SDA_OUT(void)
{
GPIO_InitType GPIO_InitStructure;

RCC_EnableAPB2PeriphClk( SDA_GPIO_CRM_CLK, ENABLE);

GPIO_InitStruct(&GPIO_InitStructure);
GPIO_InitStructure.Pin = SDA_PIN;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_Slew_Rate_High;
GPIO_InitStructure.GPIO_Current = GPIO_DC_4mA;
GPIO_InitStructure.GPIO_Pull = GPIO_Pull_Up;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitPeripheral(SDA_GPIO, &GPIO_InitStructure);
}

//设置SCL电平
void I2C_SCL(int n)
{
if(n == 1)
{
 GPIO_WriteBit(SCL_GPIO, SCL_PIN, Bit_SET); //设置SCL为高电平
}
else
{
 GPIO_WriteBit(SCL_GPIO, SCL_PIN, Bit_RESET); //设置SCL为低电平
}
}

//设置SDA电平
void I2C_SDA(int n)
{
if(n == 1)
{
 GPIO_WriteBit(SDA_GPIO, SDA_PIN, Bit_SET); //设置SDA为高电平
}
else
{
 GPIO_WriteBit(SDA_GPIO, SDA_PIN, Bit_RESET); //设置SDA为低电平
}
}

//读取SDA电平
unsigned char READ_SDA(void)
{
return GPIO_ReadInputDataBit(SDA_GPIO, SDA_PIN); //读取SDA电平
}

//I2C初始化
void I2C_Initial(void)
{
GPIO_InitType GPIO_InitStructure;

//根据GPIO组初始化GPIO时钟
RCC_EnableAPB2PeriphClk( SCL_GPIO_CRM_CLK, ENABLE);
RCC_EnableAPB2PeriphClk( SDA_GPIO_CRM_CLK, ENABLE);

//GPIO_SCL初始化设置
GPIO_InitStruct(&GPIO_InitStructure);
GPIO_InitStructure.Pin = SCL_PIN;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_Slew_Rate_High;
GPIO_InitStructure.GPIO_Current = GPIO_DC_4mA;
GPIO_InitStructure.GPIO_Pull = GPIO_Pull_Up;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitPeripheral(SCL_GPIO, &GPIO_InitStructure);

//GPIO_SDA初始化设置
GPIO_InitStruct(&GPIO_InitStructure);
GPIO_InitStructure.Pin = SDA_PIN;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_Slew_Rate_High;
GPIO_InitStructure.GPIO_Current = GPIO_DC_4mA;
GPIO_InitStructure.GPIO_Pull = GPIO_Pull_Up;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitPeripheral(SDA_GPIO, &GPIO_InitStructure);
//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(4);
I2C_SDA(0); //START:when CLK is high,DATA change form high to low
Delay_Us(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(4);
I2C_SCL(1);
I2C_SDA(1); //发送I2C总线结束信号
Delay_Us(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(2);
I2C_SCL(1);
Delay_Us(2);
I2C_SCL(0);
}

//产生NACK应答
void I2C_NAck(void)
{
I2C_SCL(0);
SDA_OUT();
I2C_SDA(1);
Delay_Us(2);
I2C_SCL(1);
Delay_Us(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;
}</code></pre>

OLED代码：

<pre>
<code>//向设备写控制命令
static void OLED_Write_CMD(unsigned char cmd)
{
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();
}

//向设备写数据
static void OLED_Write_Date(unsigned char date)
{
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();
}

//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
//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);
 }

 OLED_Set_Pos(x, y + 1);

 for(cnt = 0; cnt < 8; cnt++)
 {
 OLED_Write_Date(F8x16);
 }
}
else
{
 OLED_Set_Pos(x, y);

 for(cnt = 0; cnt < 6; cnt++)
 {
 OLED_Write_Date(F6x8);
 }
}
}

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
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 != '\0')
{
 OLED_ShowChar(x, y, chr, 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);
 addr++;
}

OLED_Set_Pos(x, y + 1);

for(cnt = 0; cnt < 16; cnt++)
{
 OLED_Write_Date(Hzk);
 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, const 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); //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[]：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[])
{
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); //画图片的点
 }
 }

 //Delay_Ms(80);
}
}

//OLED初始化
void OLED_Init(void)
{
I2C_Initial();
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
}</code></pre>

 

运行测试

76782c3660d0897299f3b7439a38cce9

测试代码

freebsder 发表于 2022-7-27 18:44

谢谢分享，期待后续。

lugl4313820 发表于 2022-8-14 22:07

其实他的硬件I2C速度会提高很多，这样刷新率就会好很多，有机会试一下。

805721366 发表于 2022-8-14 23:20

lugl4313820 发表于 2022-8-14 22:07
其实他的硬件I2C速度会提高很多，这样刷新率就会好很多，有机会试一下。

硬件I2C速度确实快，有测试过https://bbs.eeworld.com.cn/thread-1212208-1-1.html#pid3164870

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[N32L43X评测] 2.模拟I2C驱动OLED