ARM ADC程序设计

来源：互联网发布：手机上怎样查淘宝积分编辑：程序博客网时间：2024/06/08 22:46

ARM ADC程序设计

模拟信号：时间上连续，数值上也连续，数字信号：时间和数值上是离散的，而离散信号只有0或1。

S3c2440内部有8路A/D转换通道AIN0~AIN7，但是转换器只有一个，从8路中选出一路进行转换，转换精度10位(0~1024-1)，转换频率500kSPS(每秒采样500次)，在mini2440，AIN4,5,6,7，用作了触摸屏通道YM，YP，XM，XP，AIN0连接可变电阻

AIN0为模拟信号输入通道，电压作为模拟信号输入，ADC程序流程:

初始化---->启动(CPU告诉AD硬件做某项工作)---->转换结束(查询，中断)----->读取转换值

初始化：选择转换通道----->设置转换频率 SEL_MUX选择转换通道，PRSCEN为1表示使用分频器做频率设置，PRSCVL为具体分频器的值，ECFLG转换结束。

数据在0--9位

使用可调电阻作为输入ADC转换程序：#define ADC_FREQ 2500000//#define ADC_FREQ   1250000volatile U32 preScaler;void adc_init(void);int ReadAdc(int channel);static void cal_cpu_bus_clk(void);void Set_Clk(void);void beep_init(void);void beep_run(void);void delay(int times) {    int i,j;    for(i=0;i<times;i++)       for(j=0;j<400;j++);}void Main(void) {    int a0=0,tmp;    int Scom=0;    Set_Clk();//PCLK在AD转换中用到，ADC转换所需要的时钟频率    beep_init();    Uart_Init(0,115200);    Uart_Select(Scom);    Uart_Printf("\nHello World!\n");        adc_init();//    //tmp=a0;    while(1)  {        a0=ReadAdc(0); //启动转换      //  if(a0 != tmp)          Uart_Printf( "AIN0: %04d\n", a0);      //  tmp=a0;  delay(1000) ;}}void adc_init(void) {int channel=0; //AIN0，对应开发板上W1可调电阻，选择0号通道 　　//设置时钟频率preScaler = ADC_FREQ;Uart_Printf("ADC conv,freq. = %dHz\n",preScaler);preScaler = 50000000/ADC_FREQ - 1; //PCLK=50M//50M除以所需频率为预分频系数Uart_Printf("PRSCVL=PCLK/ADC_FREQ - 1=%d\n",preScaler);/*AD转换频率设置，最大频率为2.5MHz*/rADCCON = (1<<14)|(preScaler<<6)|(channel<<3);//setup channeldelay(1000);}    int ReadAdc(int channel) {/*开启AD转换，把第0位改为1，然后检查是否为0，变为0后才真正转换 */rADCCON |= 0x01; //start ADCwhile(rADCCON & 0x1);//check if Enable_start is low    while(!(rADCCON & 0x8000));//判断第15位是否为1，完成转换    return ( (int)rADCDAT0 & 0x3ff );//data寄存器最后十位} void Set_Clk(void) {int i;U8 key;U32 mpll_val = 0 ;i = 2 ;             //don't use 100M!                 //boot_params.cpu_clk.val = 3;switch ( i ) {case 0://200key = 12;mpll_val = (92<<12)|(4<<4)|(1);break;case 1://300key = 13;mpll_val = (67<<12)|(1<<4)|(1);break;case 2://400key = 14;mpll_val = (92<<12)|(1<<4)|(1);break;case 3://440!!!key = 14;mpll_val = (102<<12)|(1<<4)|(1);break;default:key = 14;mpll_val = (92<<12)|(1<<4)|(1);break;}//init FCLK=400M, so change MPLL firstChangeMPllValue((mpll_val>>12)&0xff, (mpll_val>>4)&0x3f, mpll_val&3);   //set the register--rMPLLCONChangeClockDivider(key, 12);    //the result of rCLKDIVN [0:1:0:1] 3-0 bitcal_cpu_bus_clk();    //HCLK=100M   PCLK=50M}static void cal_cpu_bus_clk(void) {static U32 cpu_freq;    static U32 UPLL;U32 val;U8 m, p, s;val = rMPLLCON;m = (val>>12)&0xff;p = (val>>4)&0x3f;s = val&3;//(m+8)*FIN*2 不要超出32位数!FCLK = ((m+8)*(FIN/100)*2)/((p+2)*(1<<s))*100;     //FCLK=400M  FIN=12000000val = rCLKDIVN;m = (val>>1)&3;p = val&1;val = rCAMDIVN;s = val>>8;switch (m) {case 0:HCLK = FCLK;break;case 1:HCLK = FCLK>>1;break;case 2:if(s&2)HCLK = FCLK>>3;elseHCLK = FCLK>>2;break;case 3:if(s&1)HCLK = FCLK/6;elseHCLK = FCLK/3;break;}if(p)PCLK = HCLK>>1;elsePCLK = HCLK;if(s&0x10)cpu_freq = HCLK;elsecpu_freq = FCLK;val = rUPLLCON;m = (val>>12)&0xff;p = (val>>4)&0x3f;s = val&3;UPLL = ((m+8)*FIN)/((p+2)*(1<<s));UCLK = (rCLKDIVN&8)?(UPLL>>1):UPLL;}void beep_init(void) {    rGPBCON &= ~(0x3<<0);    rGPBCON |=  (0x1<<0);}void beep_run(void) {    rGPBDAT |= (0x1<<0);    delay(5000);    rGPBDAT &= (0x0<<0);    delay(5000);}

0 0