STC单片机ADC转换的例子

#include 
sfr ADC_CONTR	= 0XBC;
sfr P1ASF		= 0X9D;
sfr ADC_RES		= 0XBD;
sfr ADC_RESL	= 0XBE;
#define AD_SPEED   0x60

void init_adc()
{
	ADC_CONTR = ADC_CONTR|0x80; //打开adc电源
	P1ASF = 0X01;  //设置P1.7为模拟功能
}

void adc_delay(unsigned char delay_time)        // 延时函数
{
    unsigned int n;
    while(delay_time--) 
    { 
        n = 6000;
        while(--n);
    }
}
unsigned int get_AD_result(unsigned char channel)
{
    unsigned char AD_finished=0;      
	unsigned int h_val;
	unsigned int l_val;
    ADC_RES = 0;
    ADC_RESL = 0;

    channel &= 0x07;      
    ADC_CONTR = AD_SPEED;
    _nop_();
    ADC_CONTR |= channel;       
    _nop_();
    ADC_CONTR |= 0x80;    
    adc_delay(1);            
    ADC_CONTR |= 0x08;      
    AD_finished = 0;
    while ( AD_finished ==0 )   
    {
        AD_finished = (ADC_CONTR & 0x10); 
    }
    ADC_CONTR &= 0xE7;         
    h_val = ADC_RES;
	h_val = h_val<<2;
	l_val = ADC_RESL & 0X03;
	h_val = h_val | l_val;
	return (h_val);               
}