adc.c

来自「这是ARMSYS44B0-P专业开发板的源代码」· C语言 代码 · 共 25 行

#include <string.h>
#include "..\Target\44b.h"
#include "..\Target\44blib.h"
#include "adc.h"

int ReadAdc(int ch)
{
    int i;
    static int prevCh=-1;

    if(prevCh!=ch)
    {
    	rADCCON=0x0|(ch<<2);	//setup channel.
    	for(i=0;i<150;i++);	//min. 15us
    }
    rADCCON=0x1|(ch<<2);	//Start A/D conversion
    while(rADCCON &0x1);	//To avoid The first FLAG error case.
				//(The START bit is cleared in one ADC clock.)
    while(!(rADCCON & 0x40));
    for(i=0;i<rADCPSR;i++); 	//To avoid The second FLAG error case
    prevCh=ch;
    return rADCDAT;
}