[N32L43X评测] 4.模拟SPI驱动OLED
<p><span style="font-family:宋体;">前两篇<a href="https://bbs.eeworld.com.cn/thread-1212206-1-1.html" target="_blank"> 2.模拟I2C驱动OLED</a> <a href="https://bbs.eeworld.com.cn/thread-1212208-1-1.html" target="_blank"> 3.硬件I2C驱动OLED</a>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。</span></p><p><span style="font-family:宋体;">SPI是一种高速、全双工、同步串行总线，SPI与I2C对比：</span></p>
<p><span style="font-family:宋体;"> SPI是全双工，I2C是半双工</span></p>
<p><span style="font-family:宋体;"> SPI只能有一个主机，I2C支持多主机多从机</span></p>
<p><span style="font-family:宋体;"> I2C占用更少的GPIO，更节省资源<br />
SPI的数据位宽更灵活，可以根据需要选择多位数数据宽度<br />
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<br />
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<br />
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<br />
SPI、I2C都应用于板内器件短距离通讯</span></p>
<p><span style="font-family:宋体;">SPI总线详解可参考：</span></p>
<p></p>
<p><span style="font-family:宋体;">此篇主要介绍GPIO软件模拟实现SPI来驱动0.96寸OLED显示屏</span></p>
<p><span style="color:#f39c12;"><strong><span style="font-family:宋体;">硬件连接</span></strong></span></p>
<p><span style="font-family:宋体;">GND —— GND</span></p>
<p><span style="font-family:宋体;">VCC —— 3.3V</span></p>
<p><span style="font-family:宋体;">DO —— PB13<br />
DI —— PB15<br />
RES —— PC7<br />
DC —— PC6<br />
CS —— PB12</span></p>
<p class="imagemiddle" style="text-align: center;"></p>
<p><span style="color:#f39c12;"><strong><span style="font-family:宋体;">软件代码</span></strong></span></p>
<p><span style="font-family:宋体;">SPI代码：</span></p>
<pre>
<code>//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;
}</code></pre>
<p><span style="font-family:宋体;">OLED代码变更部分：</span></p>
<pre>
<code>//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 = {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 = {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
}</code></pre>
<p><span style="font-family:宋体;"><span style="color:#f39c12;"><strong>运行测试</strong></span></span></p>
<p>945d66b1b2b119468f1569493968fdf4</p>
<p><span style="color:#f39c12;"><strong><span style="font-family:宋体;">测试代码</span></strong></span></p>
<p></p>
<p> </p>
<p>谢谢分享，期待后续。</p>
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