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伴随着生活质量的提高，人们对空气质量的要求也开始提升，这里就介绍一种空气质量检测器的实现方法。

要进行空气质量检测就离不开相应的检测器配合，这里采用的是一款体积小巧的功能模块，其外观见图1所示。

图1 功能模块外观

该模块共有4个引脚，是以串口通信的方式来工作，其引脚排列如图2所示。

图2 引脚功能

该模块所依照的通信协议要求见图3所示，其检测到数据结构见图4所示。

图3 通信参数

图4 检测值数据结构

需要说明的是：B1和B2的内容是模块的固定地址，B9则是检测结果的校验码，其内容等于B1至B7的数据之和，只占用一个字节空间。该模块的检测值是以气体浓度为单位，即mg/m3，精度为0.001。

为实现空气质量的检测及显示，它以RA6E2 地奇星开发板为控制核心，以1.8寸TFT显示屏为显示器件，并通过扩展板进行连接。

为此，需要以RASC来配置所涉及的引脚，串口的参数配置见图5所示。

图5 参数配置

受扩展板引脚排列顺序的制约，其不便以SPI的方式来驱动TFT显示屏，故以软件模拟的方式来驱动。

为输出高低电平，所进行的定义语句为：

#define LCD_CS_CLR   R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_00_PIN_13, BSP_IO_LEVEL_LOW)

#define LCD_CS_SET   R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_00_PIN_13, BSP_IO_LEVEL_HIGH)

#define LCD_DC_CLR   R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_00_PIN_14, BSP_IO_LEVEL_LOW)

#define LCD_DC_SET   R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_00_PIN_14, BSP_IO_LEVEL_HIGH)

#define LCD_RST_CLR  R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_05_PIN_00, BSP_IO_LEVEL_LOW)

#define LCD_RST_SET  R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_05_PIN_00, BSP_IO_LEVEL_HIGH)

#define LCD_SDI_CLR  R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_02_PIN_07, BSP_IO_LEVEL_LOW)

#define LCD_SDI_SET  R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_02_PIN_07, BSP_IO_LEVEL_HIGH)

#define LCD_SCK_CLR  R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_03_PIN_02, BSP_IO_LEVEL_LOW)

#define LCD_SCK_SET  R_IOPORT_PinWrite(&IOPORT_CFG_CTRL, BSP_IO_PORT_03_PIN_02, BSP_IO_LEVEL_HIGH)

对显示屏的初始化函数为：

void Lcd_Init(void)
{ 
unsigned int i; 
Lcd_Reset(); .
Lcd_WriteIndex(0x11); 
R_BSP_SoftwareDelay(120, BSP_DELAY_UNITS_MILLISECONDS);
Lcd_WriteIndex(0xB1); 
Lcd_WriteData(0x01); 
Lcd_WriteData(0x2C); 
Lcd_WriteData(0x2D); 
Lcd_WriteIndex(0xB2); 
Lcd_WriteData(0x01); 
Lcd_WriteData(0x2C); 
Lcd_WriteData(0x2D); 
Lcd_WriteIndex(0xB3); 
Lcd_WriteData(0x01); 
Lcd_WriteData(0x2C); 
Lcd_WriteData(0x2D); 
Lcd_WriteData(0x01); 
Lcd_WriteData(0x2C); 
Lcd_WriteData(0x2D); 
Lcd_WriteIndex(0xB4);  
Lcd_WriteData(0x07); 
Lcd_WriteIndex(0xC0); 
Lcd_WriteData(0xA2); 
Lcd_WriteData(0x02); 
Lcd_WriteData(0x84); 
Lcd_WriteIndex(0xC1); 
Lcd_WriteData(0xC5); 
Lcd_WriteIndex(0xC2); 
Lcd_WriteData(0x0A); 
Lcd_WriteData(0x00); 
Lcd_WriteIndex(0xC3); 
Lcd_WriteData(0x8A); 
Lcd_WriteData(0x2A); 
Lcd_WriteIndex(0xC4); 
Lcd_WriteData(0x8A); 
Lcd_WriteData(0xEE);  
Lcd_WriteIndex(0xC5); 
Lcd_WriteData(0x0E);  
Lcd_WriteIndex(0x36);  
Lcd_WriteData(0xC0); 
Lcd_WriteIndex(0xe0); 
Lcd_WriteData(0x0f); 
Lcd_WriteData(0x1a); 
Lcd_WriteData(0x0f); 
Lcd_WriteData(0x18); 
Lcd_WriteData(0x2f); 
Lcd_WriteData(0x28); 
Lcd_WriteData(0x20); 
Lcd_WriteData(0x22); 
Lcd_WriteData(0x1f); 
Lcd_WriteData(0x1b); 
Lcd_WriteData(0x23); 
Lcd_WriteData(0x37); 
Lcd_WriteData(0x00);  
Lcd_WriteData(0x07); 
Lcd_WriteData(0x02); 
Lcd_WriteData(0x10); 
Lcd_WriteIndex(0xe1); 
Lcd_WriteData(0x0f); 
Lcd_WriteData(0x1b); 
Lcd_WriteData(0x0f); 
Lcd_WriteData(0x17); 
Lcd_WriteData(0x33); 
Lcd_WriteData(0x2c); 
Lcd_WriteData(0x29); 
Lcd_WriteData(0x2e); 
Lcd_WriteData(0x30); 
Lcd_WriteData(0x30); 
Lcd_WriteData(0x39); 
Lcd_WriteData(0x3f); 
Lcd_WriteData(0x00); 
Lcd_WriteData(0x07); 
Lcd_WriteData(0x03); 
Lcd_WriteData(0x10);  
Lcd_WriteIndex(0x2a);
Lcd_WriteData(0x00);
Lcd_WriteData(0x00);
Lcd_WriteData(0x00);
Lcd_WriteData(0x7f);
Lcd_WriteIndex(0x2b);
Lcd_WriteData(0x00);
Lcd_WriteData(0x00);
Lcd_WriteData(0x00);
Lcd_WriteData(0x9f); 
Lcd_WriteIndex(0xF0);   
Lcd_WriteData(0x01); 
Lcd_WriteIndex(0xF6); 
Lcd_WriteData(0x00);  
Lcd_WriteIndex(0x3A); 
Lcd_WriteData(0x05);   
Lcd_WriteIndex(0x29);  
}

为进行汉字显示，其提取字模时的方式如图6所示。

图6 字模提取方式

针对所提取的字模，相应的显示函数为：

在此基础上，实现空气质量检测与显示的主程序为：

经程序的编译及下载，其测试效果如图7所示，说明效果符合预期要求。

图7  检测效果

演示视频：

https://www.bilibili.com/video/BV1YXzXBNE6H/?vd_source=f302fc0cc3a0425328db53a3b92082ca