STM32 软件IIC 控制OLED 显示屏

1. 硬件IIC 实在是太难用了，各种卡死，各种发不出来数据，没那么多时间折腾了，还是用软件IIC 先吧，初始化

void OLED_Software_IIC_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStruct;

    RCC_AHBPeriphClockCmd(OLED_SOFTWARE_IIC_PORT_B | OLED_SOFTWARE_IIC_AF_CLOCK, ENABLE);

    GPIO_InitStruct.GPIO_Pin = OLED_IIC_SDA_PIN_B11 | OLED_IIC_SCL_PIN_B10;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_40MHz;
    GPIO_Init(GPIOB, &GPIO_InitStruct); // PB11 - SDA, PB10 - SCL

    GPIO_SetBits(GPIOB, OLED_IIC_SDA_PIN_B11 | OLED_IIC_SCL_PIN_B10);

    OLED_IIC_Stop();
}

2. 一些宏定义,带FreeRTOS 实时操作系统，系统节拍设置为1ms，系统主频设置为32Mhz

#define OLED_USE_SOFTWARE_IIC

#define OLED_SOFTWARE_IIC_PORT_B    RCC_AHBPeriph_GPIOB // SCL - PB10, SDA -PB11
#define OLED_SOFTWARE_IIC_AF_CLOCK    RCC_APB1Periph_I2C2

#define IIC_TIMEOUT_COUNTER    0x2000 // iic transmit timeout

#define OLED_IIC_SCL_PIN_B10    GPIO_Pin_10
#define OLED_IIC_SDA_PIN_B11    GPIO_Pin_11
#define OLED_SCL_H()    GPIO_SetBits(GPIOB, OLED_IIC_SCL_PIN_B10)
#define OLED_SCL_L()    GPIO_ResetBits(GPIOB, OLED_IIC_SCL_PIN_B10)

#define OLED_ADDRESS    0x78 // 0x78: device address + write, 0x79 - device address + read
#define IIC_CMD_LEN    2

#define OLED_SDA_H()    GPIO_SetBits(GPIOB, OLED_IIC_SDA_PIN_B11)
#define OLED_SDA_L()    GPIO_ResetBits(GPIOB, OLED_IIC_SDA_PIN_B11)

#define OLED_SDA_READ()    GPIO_ReadInputDataBit(GPIOB, OLED_IIC_SDA_PIN_B11)

3. 延时函数，CPU 阻塞，空转

static void IIC_Delay(void)
{
   uint8_t temp;

   for (temp = 0; temp < 10; temp++)
   {
       // do nothing
   }
}

4. 起始信号

static void OLED_IIC_Start(void)
{
    OLED_SDA_H();
    OLED_SCL_H();

    IIC_Delay();
    OLED_SDA_L();
    IIC_Delay();
    OLED_SCL_L();
    IIC_Delay();
}

5. 停止信号

static void OLED_IIC_Stop(void)
{
   OLED_SDA_L();
   OLED_SCL_H();
   IIC_Delay();
   OLED_SDA_H();
   IIC_Delay();
}

6. 发送一个字节的数据

static void OLED_IIC_SendByte(uint8_t data)
{
   uint8_t index;
   GPIO_InitTypeDef GPIO_InitStruct;

   for (index = 0; index < 8; index++) // send one byte data, first send MSB (bit[7]), send LSB at the last (bit[0])
   {
       if (data & 0x80)
       {
           OLED_SDA_H(); // send 1
       }
       else
       {
           OLED_SDA_L(); // send 0
       }
       IIC_Delay();
       OLED_SCL_H();
       IIC_Delay();
       OLED_SCL_L();
       data <<= 1; // send next bit (MSB -> LSB)
       IIC_Delay();
   }
//    OLED_SDA_H();
   GPIO_InitStruct.GPIO_Pin = OLED_IIC_SDA_PIN_B11;
   GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN;
   GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;

   GPIO_Init(GPIOB, &GPIO_InitStruct);

   IIC_Delay();
}

7. 发送一个字节数据后等待从机回复一个ACK 信号

uint8_t OLED_IIC_WaitAck(void)
{
   uint8_t ret;

   OLED_SCL_H();
   if (OLED_SDA_READ())
   {
       ret = 1; // not received ACK signal, wait fail
   }
   else
   {
       ret = 0; // received ACK signal, wait success
   }
   IIC_Delay();
   OLED_SCL_L();
   IIC_Delay();

   return ret;
}

8. GPIO 重新初始化

static void OLED_SoftwareIIC_SDA_Resume(void)
{
    GPIO_InitTypeDef GPIO_InitStruct;

    GPIO_InitStruct.GPIO_Pin = OLED_IIC_SDA_PIN_B11;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_40MHz;
    GPIO_Init(GPIOB, &GPIO_InitStruct); // PB11 - SDA
}

9. 模仿HAL库写的一个自己的函数,实现功能，发送设备地址+读写控制，再发送0x00，表示发的是命令，再发一个字节数据，具体的内容，数据，共发了三个字节的数据，加了超时退出机制

/*
 * imitate the stm32 HAL library, achieve myself's software i2c send function
 * deviceAddr: 0x78 - device address and write operation, 0x79 - device address and read operation
 */
static void HAL_I2C_Master_Transmit(I2C_TypeDef *I2Cx, uint8_t deviceAddr, uint8_t buff[], uint16_t buffLen, uint32_t timeout)
{
    uint32_t temp;
    uint16_t index;

    temp = timeout;

    OLED_IIC_Start();

    IIC_Delay();
    OLED_IIC_SendByte(deviceAddr); // device address and write bit

    while (OLED_IIC_WaitAck())
    {
        temp--;
        if (0 == temp)
        {
            return;
        }
        IIC_Delay();
    }

    OLED_SoftwareIIC_SDA_Resume();
    for (index = 0; index < buffLen; index++)
    {
        OLED_IIC_SendByte(buff[index]);
        IIC_Delay();
        while (OLED_IIC_WaitAck())
        {
            temp--;
            if (0 == temp)
            {
                return;
            }
            IIC_Delay();
        }
        OLED_SoftwareIIC_SDA_Resume();
        IIC_Delay();
    }

    OLED_IIC_Stop();
}

10. 向OLED 发送指令函数

static void OLED_SendCmd(uint8_t cmd)
{
    uint8_t sendBuff[2];

    sendBuff[0] = 0x00;
    sendBuff[1] = cmd;

    HAL_I2C_Master_Transmit(I2C2, OLED_ADDRESS, sendBuff, IIC_CMD_LEN, IIC_TIMEOUT_COUNTER);
}

11. OLED 初始化函数,OLED 用的龙科显示公式的产品，控制IC 用的是CH1116G，他们给我发是资料却是SH1106的

void OLED_Init(void)
{
    delay_xms(200); // oled startup slowly than stm32l151c8t6
    INFO_LOG("[OLED_Init] init start\r\n");

    OLED_SendCmd(0xAE); // display off

    OLED_SendCmd(0x02); // set colum start address, low 4-bits
    OLED_SendCmd(0x10); // set colum end address, high 4-bits

    OLED_SendCmd(0x40); // set start line (first row)
    OLED_SendCmd(0xB0); // set page address

    delay_xms(5);
    OLED_SendCmd(0x81); // set contrast ratio (对比度)
    delay_xms(5);
    OLED_SendCmd(0xCF); // 128
    delay_xms(5);

    OLED_SendCmd(0xA1); // set segment remapping, from right to left

    OLED_SendCmd(0xA6); // forward display, normal or reverse

    OLED_SendCmd(0xA8); // multiple reuse rate, multiple ratio (多路复用率)
    OLED_SendCmd(0x3F); // duty = 1 / 64

    OLED_SendCmd(0xAD); // set charge pump enable
    OLED_SendCmd(0x8B); // enable DC-DC

    OLED_SendCmd(0x33); // set VPP = 10V

    OLED_SendCmd(0xC8); // set output scan direction, COM[N - 1] to COM[0], COM scan direction

    OLED_SendCmd(0xD3); // set display offset
    OLED_SendCmd(0x00); // 0x00

    OLED_SendCmd(0xD5); // set internal clock frequence, set osc frequency
    OLED_SendCmd(0xC0);

    OLED_SendCmd(0xD9); // set pre-charge period
    OLED_SendCmd(0x1F); // 0x22

    OLED_SendCmd(0xDA); // set COM pins, pin layout
    OLED_SendCmd(0x12);

    OLED_SendCmd(0xDB); // set electrical level, set VCOMH
    OLED_SendCmd(0x40);

    OLED_SendCmd(0xAF); // enable display, display on

    INFO_LOG("[OLED_Init][alfred01] init complete\r\n");
    INFO_LOG("[OLED_Init] init complete\r\n");
}

12. OLED 测试函数

void OLED_Test(void)
{
    OLED_SendCmd(0xB0); // page 0
    OLED_SendCmd(0x02); // colume 0, low 4-bits
    OLED_SendCmd(0x10); // colume 0, high 4-bits

    uint8_t sendBuff[] = {0x40, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA};
    HAL_I2C_Master_Transmit(I2C2, OLED_ADDRESS, sendBuff, sizeof(sendBuff), IIC_TIMEOUT_COUNTER);
}