s3c2440的A/D转换应用

   A/D转换，又称为模数转换，是将模拟信号转换为计算机能够处理的数字信号。s3c2440集成了8通道10位CMOS A/D转换器。
 
       对于s3c2440来说，实现A/D转换比较简单，主要应用的是ADC控制寄存器ADCCON和ADC转换数据寄存器ADCDAT0。寄存器ADCDAT0的低10位用于存储A/D转换后的数据。寄存器ADCCON的第15位用于标识A/D转换是否结束。第14位用于使能是否进行预分频，而第6位到第13位则存储的是预分频数值，因为A/D转换的速度不能太快，所以要通过预分频处理才可以得到正确的A/D转换速度，如我们想要得到A/D转换频率为1MHz，则预分频的值应为49。第3位到第5位表示的是A/D转换的通道选择。第2位可以实现A/D转换的待机模式。第1位用于是否通过读取操作来使能A/D转换的开始。第0位则是在第1位被清零的情况下用于开启A/D转换。
 
       下面我们就给出一个A/D转换的实例。我们在AIN2引脚上接了一个温度传感器，被检测的温度范围为0度~99度，它对应于A/D转换数据的0~0x3FF。检测到的温度被实时地显示在LCD上，这里我们只显示温度的整数部分。由于要实时显示数据，因此就涉及到LCD刷新的问题，如果处理得不好，会出现LCD闪烁的现象。所以在程序中，我们只对要刷新的区域进行刷新处理，而对其他区域不更新，这样就有效地防止了LCD的闪烁。
 
 
……  ……
unsigned char degree[]=                      //℃                48×48字模
{
……  ……
};
unsigned char colon[]=                       //：                48×48字模
{
……  ……
};
unsigned char du[]=                            //度                48×48字模
{
……  ……
};
unsigned char wen[]=                         //温                48×48字模
{
……  ……
};
unsigned char digital[]=                      //0~9的ASCII码字符数组                24×48字模
{
……  ……
};
 
//重新改写刷屏的程序，确定了要刷屏的区域范围
void Brush_Background( int x,int y,int width,int height,U32 c)
{
       int i,j ;
             
for( j = y ; j        {
       for( i = x ; i < width ; i++ )
              {
                     LCD_BUFFER[j][i] = c ;
       }
       }
}
 
int readADC(void)
{
       rADCCON = (1<<14)|(49<<6)|(2<<3);              //设置预分频器和A/D通道
      
       rADCCON|=0x1;                                      //启动A/D转换
 
       while(rADCCON & 0x1)
              ;                                                //确认A/D转换是否开始
       while(!(rADCCON & 0x8000))
              ;                                                //等待A/D转换的结束
 
       return ( (int)rADCDAT0 & 0x3ff );      //读取A/D转换的数据
}
 
void Main(void)
{
       int temperature,oldTemp;
       unsigned char value[2],oldValue;
 
LCD_Init();   
       rLCDCON1|=1;
   
Brush_Background(0,0,LCD_WIDTH,LCD_HEIGHT,0xFFFFFF);          //刷写这个LCD
       Draw_Text48(16,96,0xff0000,wen)  ;
Draw_Text48(64,96,0xff0000,du)  ;
       Draw_Text48(112,96,0xff0000,colon)  ;
Draw_Text48(208,96,0xff0000,degree)  ;
 
oldTemp=0;
       oldValue=0;
  
while(1)
       {
          
       temperature = (int)readADC()*99/0x3ff;                   //读取温度
              if(oldTemp != temperature)                        //判断温度是否有变化
       {
                     oldTemp = temperature;
                    
                     value[0] = (unsigned char)temperature/10;                 //温度的十位数据
              value[1] = (unsigned char)temperature%10;               //温度的个位数据
                     if(oldValue!=value[0])                        //十位数据没有变化就不需要更新
              {
                            oldValue=value[0];
                     Brush_Background(150,96,150+24,96+48,0xFFFFFF);             //刷新十位数据的区域
                            Draw_ASCII(150,96,0xff0000,digital+144*value[0]);                     //显示十位数据
              }
                     Brush_Background(174,96,174+24,96+48,0xFFFFFF);                    //刷新个位数据区域
              Draw_ASCII(174,96,0xff0000,digital+144*value[1]);                            //显示个位数据
              }
       delay(1000000);
       }
}
 

 
既然可以上传图片了，我就把LCD显示的结果给大家展示一下！
 
 
 

 
 
鉴于有一些网友向我索要Draw_Text48函数和Draw_ASCII函数，那么我就索性把它们也贴出来。
 
void PutPixel(U32 x,U32 y, U32 c )
{
LCD_BUFFER[y][x] = c;
}
 
//48*48
void Draw_Text48(U32 x,U32 y,U32 color,unsigned char ch[])
{
       unsigned short int i,j;
       unsigned char mask,buffer;
      
       for(i=0;i<48;i++)
       {
              mask=0x80;
              buffer=ch[i*6];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j,y+i,color);
                     }
                     mask=mask>>1;                  
              }
              mask=0x80;
              buffer=ch[i*6+1];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+8,y+i,color);
                     }
                     mask=mask>>1;                  
              }
             
              mask=0x80;
              buffer=ch[i*6+2];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+16,y+i,color);
                     }
                     mask=mask>>1;                  
              }
              mask=0x80;
              buffer=ch[i*6+3];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+24,y+i,color);
                     }
                     mask=mask>>1;                  
              }
             
              mask=0x80;
              buffer=ch[i*6+4];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+32,y+i,color);
                     }
                     mask=mask>>1;                  
              }
              mask=0x80;
              buffer=ch[i*6+5];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+40,y+i,color);
                     }
                     mask=mask>>1;                  
              }
       }
}
 
//24*48 for ASCII
void Draw_ASCII(U32 x,U32 y,U32 color,const unsigned char ch[])
{
       unsigned short int i,j;
       unsigned char mask,buffer;
      
       for(i=0;i<48;i++)
       {
              mask=0x80;
              buffer=ch[i*3];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j,y+i,color);
                     }
                     mask=mask>>1;                  
              }
             
              mask=0x80;
              buffer=ch[i*3+1];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+8,y+i,color);
                     }
                     mask=mask>>1;                  
              }
             
              mask=0x80;
              buffer=ch[i*3+2];
              for(j=0;j<8;j++)
              {
                    
                     if(buffer&mask)
                     {
                            PutPixel(x+j+16,y+i,color);
                     }
                     mask=mask>>1;                  
              }
       }
}