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上一篇介绍了SWM221CBT7显示开发板的基本用法，这次来介绍如何用GPIO口以模拟I2C的方式来驱动OLED屏。

常见的OLED屏，有0.91寸和0.96寸这2种，除初始化的函数不同外，其它的基本相同。

为后续实现硬件驱动的方便，这里选取的连接引脚就选用对应的I2C引脚。

图1 I2C引脚 

将所用引脚配置为输出模式的函数为：

void oled_config(void)

{

    GPIO_Init(GPIOA, PIN6, 1, 0, 0, 0);

   GPIO_Init(GPIOA, PIN7, 1, 0, 0, 0);

}

为便于输出高低电平的需要，相应的定义语句为：

#define OLED_SCLK_Clr()   GPIO_ClrBit(GPIOA, PIN6)

#define OLED_SCLK_Set()   GPIO_SetBit(GPIOA, PIN6) 

#define OLED_SDIN_Clr()   GPIO_ClrBit(GPIOA, PIN7)

#define OLED_SDIN_Set()   GPIO_SetBit(GPIOA, PIN7) 

使显示屏工作的参数设置为：

#define OLED_MODE   0

#define SIZE          16

#define XLevelL     0x02

#define XLevelH     0x10

#define Max_Column 128

#define Max_Row  64

#define Brightness 0xFF

#define X_WIDTH      128

#define Y_WIDTH      64

#define OLED_CMD    0

#define OLED_DATA    1 

使用GPIO口模拟I2C方式发送字节数据的函数为：

void Write_IIC_Byte(unsigned char IIC_Byte)

{

unsigned char i;

unsigned char m,da;

da=IIC_Byte;

OLED_SCLK_Clr();

for(i=0;i<8;i++)

{

m=da;

m=m&0x80;

if(m==0x80)

{

OLED_SDIN_Set();

}

else 

{

OLED_SDIN_Clr();

}

da=da<<1;

delay_us(3);

OLED_SCLK_Set();

delay_us(3);

OLED_SCLK_Clr();

delay_us(3);

}

}

对0.91寸屏的初始化函数为：

void OLED_Init(void)

{

    Write_IIC_Command(0xAE); 

    Write_IIC_Command(0x40);

    Write_IIC_Command(0xb0);

    Write_IIC_Command(0xc8);

    Write_IIC_Command(0x81);

    Write_IIC_Command(0xff);

    Write_IIC_Command(0xa1);

    Write_IIC_Command(0xa6);

    Write_IIC_Command(0xa8);

    Write_IIC_Command(0x1F);

    Write_IIC_Command(0xd3);

    Write_IIC_Command(0x00);

    Write_IIC_Command(0xd5);

    Write_IIC_Command(0xf0);

    Write_IIC_Command(0xd9);

    Write_IIC_Command(0x22);

    Write_IIC_Command(0xda);

    Write_IIC_Command(0x02);

    Write_IIC_Command(0x8d);

    Write_IIC_Command(0x14);

    Write_IIC_Command(0xdb);

    Write_IIC_Command(0x49);

    Write_IIC_Command(0xaf);

}

实现驱动测试的主程序为：

int main(void)

{

SystemInit();

GPIO_Init(GPIOA, PIN5, 1, 0, 0, 0);

oled_config();

OLED_Init();

OLED_Clear();

        OLED_ShowString(0,0,"SWDM221CBA5",16);

OLED_ShowString(0,2,"jinglixixi",16);

while(1)

{

GPIO_SetBit(GPIOA, PIN5);

delay_ms(300);

GPIO_ClrBit(GPIOA, PIN5);

delay_ms(300);

}

}

经程序的编译和下载，其测试效果如图2所示，说明驱动有效。

图2 测试效果 

若变更初始化函数，则可实现0.96寸显示屏的驱动，其初始化函数为：

void OLED_Init(void)

{

    Write_IIC_Command(0xAE); 

    Write_IIC_Command(0x20); 

    Write_IIC_Command(0x10);

    Write_IIC_Command(0xb0);

    Write_IIC_Command(0xc8);

    Write_IIC_Command(0x00);

    Write_IIC_Command(0x10);

    Write_IIC_Command(0x40);

    Write_IIC_Command(0x81);

    Write_IIC_Command(0xdf);

    Write_IIC_Command(0xa1);

    Write_IIC_Command(0xa6);

    Write_IIC_Command(0xa8);

    Write_IIC_Command(0x3F);

    Write_IIC_Command(0xa4);

    Write_IIC_Command(0xd3);

    Write_IIC_Command(0x00);

    Write_IIC_Command(0xd5);

    Write_IIC_Command(0xf0);

    Write_IIC_Command(0xd9);

    Write_IIC_Command(0x22); 

    Write_IIC_Command(0xda);

    Write_IIC_Command(0x12);

    Write_IIC_Command(0xdb);

    Write_IIC_Command(0x20);

    Write_IIC_Command(0x8d);

    Write_IIC_Command(0x14);

    Write_IIC_Command(0xaf);

}

经测试，去显示效果如图3所示，说明驱动有效且成功。

图3 显示效果