[N32L43X评测] 4.模拟SPI驱动OLED

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[N32L43X评测] 4.模拟SPI驱动OLED [复制链接]

前两篇[N32L43X评测] 2.模拟I2C驱动OLED [N32L43X评测] 3.硬件I2C驱动OLED介绍了I2C总线驱动OLED显示屏，此篇介绍SPI串行总线驱动OLED显示屏。

SPI是一种高速、全双工、同步串行总线，SPI与I2C对比：

SPI是全双工，I2C是半双工

SPI只能有一个主机，I2C支持多主机多从机

    I2C占用更少的GPIO，更节省资源
    SPI的数据位宽更灵活，可以根据需要选择多位数数据宽度
    SPI协议没有响应机制，主机无法得知从机是否接收到所发的数据，需采用一些方法来防止数据丢帧
    SPI协议可以做到非常高的速率，每一个SCLK都可以进行数据的传输，通过引入CRC等校验方法，可以即高速传输数据，又能保持数据的准确度
    I2C通过器件地址来选择从机，从机数量的增加不会导致GPIO的增加，而SPI通过CS片选信号选择从机，每增加一个从机就要多占用一个GPIO；也可以通过加入译码器来实现多从机控制
    SPI、I2C都应用于板内器件短距离通讯

SPI总线详解可参考：

SPI Block Guide V04.01.pdf (428.89 KB, 下载次数: 1)

此篇主要介绍GPIO软件模拟实现SPI来驱动0.96寸OLED显示屏

硬件连接

GND —— GND

VCC —— 3.3V

DO —— PB13
DI —— PB15
RES —— PC7
DC —— PC6
CS —— PB12

软件代码

SPI代码：

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//SPI初始化
void SPI_Initial(void)
{
    GPIO_InitType GPIO_InitStructure;

    //根据GPIO组初始化GPIO时钟
    RCC_EnableAPB2PeriphClk( RCC_SPI_CS | RCC_SPI_SCK | RCC_SPI_MOSI | RCC_SPI_MISO, ENABLE);

    //GPIO_CS初始化设置
    GPIO_InitStruct(&GPIO_InitStructure);
    GPIO_InitStructure.Pin = PIN_SPI_CS;
    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(PORT_SPI_CS, &GPIO_InitStructure);
    //GPIO_SCK初始化设置
    GPIO_InitStruct(&GPIO_InitStructure);
    GPIO_InitStructure.Pin = PIN_SPI_SCK;
    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(PORT_SPI_SCK, &GPIO_InitStructure);
    //GPIO_MISO初始化设置
    GPIO_InitStruct(&GPIO_InitStructure);
    GPIO_InitStructure.Pin = PIN_SPI_MISO;
    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(PORT_SPI_MISO, &GPIO_InitStructure);
    //GPIO_MOSI初始化设置
    GPIO_InitStruct(&GPIO_InitStructure);
    GPIO_InitStructure.Pin = PIN_SPI_MOSI;
    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(PORT_SPI_MOSI, &GPIO_InitStructure);

    SPI_CS_DISABLE;
    SPI_SCK_HIGH;
    SPI_MOSI_HIGH;

}


//SPI写一字节数据,TxData --- 发送的字节数据
void SPI_WriteByte(unsigned char TxData)
{
    unsigned char cnt;

    for(cnt = 0; cnt < 8; cnt++)
    {
        SPI_SCK_LOW;                                 //时钟 - 低
        Delay_Us(1);

        if(TxData & 0x80)                            //发送数据
            SPI_MOSI_HIGH;
        else
            SPI_MOSI_LOW;

        TxData <<= 1;

        Delay_Us(1);
        SPI_SCK_HIGH;                                //时钟 - 高
        Delay_Us(1);
    }
}


//SPI读一字节数据,读回来的字节数据
unsigned char SPI_ReadByte(void)
{
    unsigned char cnt;
    unsigned char RxData = 0;

    for(cnt = 0; cnt < 8; cnt++)
    {
        SPI_SCK_LOW;                                 //时钟 - 低
        Delay_Us(1);

        RxData <<= 1;

        if(SPI_MISO_READ)                            //读取数据
        {
            RxData |= 0x01;
        }

        SPI_SCK_HIGH;                                //时钟 - 高
        Delay_Us(1);
    }

    return RxData;
}

OLED代码变更部分：

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//向设备写控制命令
static void OLED_Write_CMD(unsigned char cmd)
{
    #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_I2C
    unsigned char tx_buf[BUF_SIZE] = {0x00, cmd};
    i2c_master_send(tx_buf, BUF_SIZE);
    #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 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_I2C
    unsigned char tx_buf[BUF_SIZE] = {0x40, date};
    i2c_master_send(tx_buf, BUF_SIZE);
    #endif
    #ifdef SW_SPI
    OLED_CS_LOW;
    OLED_DC_HIGH;
    SPI_WriteByte(date);
    OLED_CS_HIGH;
    #endif
}

//OLED初始化
void OLED_Init(void)
{
    #ifdef SW_I2C
    I2C_Initial();
    #endif
    #ifdef SW_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
}