max111.c

_计算实用教程Visual C++6.0实用教程

/*max111.c*/
#include<stdio.h>
#include<dos.h>
#include<time.h>
#include <conio.h>
#include <process.h>
/* Interface for 14 bit MAX111 */

/* 
   Printer adapter pin usage
   -------------------------
   D7 (9)  = Din
   D0 (2)  = SCLK
   C1* (14)= CS*
   S7* (11)= Dout
   S6  (10)= BUSY
*/

#define TRUE 1
#define FALSE 0

/* Global variable has address of DATA port of LPT1 */
unsigned int dport_lpt1; /* data port address*/

int chk_lpt(void); /*Check if LPT1 is present*
void disble_adc(void); /*Pull ADC CS* high to disable ADC*/
void enable_adc(void); /*Pull ADC CS* low to enable ADC*/
void chk_adc_status(void); /*Check ADC for End of Conversion*/
unsigned int read_adc(unsigned int prog_word);


unsigned int read_adc(unsigned int prog_word)
{
unsigned char temp2, temp1, temp3;
unsigned int temp_val, adc_val, out_val;

out_val=prog_word;

chk_adc_status();

enable_adc();

adc_val=0;

		for(temp2=0; temp2<16; temp2++)
	{
		temp1=inportb(dport_lpt1);
		temp1=temp1 & 0x7e;


		temp_val=out_val << temp2;
		temp_val=temp_val >> 8;
		temp_val=temp_val & 0x0080;

		temp1=temp1 | (unsigned char)temp_val;
		outportb(dport_lpt1, temp1); /*send data*/
		temp1=temp1 | 0x01;
		outportb(dport_lpt1, temp1); /*send Sclk*/

		temp3=inportb(dport_lpt1+1) & 0x80; /*read data*/
		temp3=temp3 ^ 0x80;
		temp_val=(unsigned int)temp3;
		temp_val=temp_val<<8;
		temp_val=temp_val & 0x8000;
		temp_val=temp_val>>temp2;
		adc_val=temp_val | adc_val;

		temp1=temp1 & 0xfe;
		outportb(dport_lpt1, temp1);

	}

outportb(dport_lpt1+2, (inportb(dport_lpt1+2) & 0xfd) );

return adc_val;
}

void chk_adc_status(void)
{

unsigned char tempa;

	tempa=inportb( dport_lpt1+1);
	tempa=tempa & 0x40;
		while(!tempa)
			{
			tempa=inportb(dport_lpt1+1);
			tempa=tempa & 0x40;
			}

}


void disable_adc(void)
{
unsigned char tempx;

tempx=inportb(dport_lpt1+2);
tempx=tempx & 0xfd;
outportb(dport_lpt1+2, tempx);

}

void enable_adc(void)
{
unsigned char tempy;

		tempy=inportb(dport_lpt1+2);
		tempy=tempy | 0x2;
		outportb(dport_lpt1+2, tempy);
}

int chk_lpt(void)
{

/*Get LPT1 port addresses */
dport_lpt1 = peek(0x40,0x08);
if(dport_lpt1 == 0)
return FALSE;

/* else return TRUE */
return TRUE;
}



main()
{
float final_vol;
unsigned int adc_val;
unsigned char temp1;

clrscr();

/*Check if Printer port is present*/

if( chk_lpt() == FALSE) 
{printf("\nPrinter port not available... aborting"); exit(1);}
printf("\nPrinter port is at %X hex", dport_lpt1);

/*Disable the ADC*/

disable_adc();

/*set clock and data low*/
temp1=inportb(dport_lpt1);
temp1=temp1 & 0x7e;
outportb(dport_lpt1, temp1);

printf("\nWaiting for the ADC to be ready...");

chk_adc_status();

printf("\nADC is ready for conversion...");

/*perform offset correction for channel 1 */
adc_val=read_adc(0x8c8c); 

/*perform gain claibration*/
adc_val=read_adc(0x8c88);

/*perform offset null*/
adc_val=read_adc(0x8c84);

/*Now convert indefinately on channel 1*/ 
	for(;;)
		{
	adc_val=read_adc(0x8c80);
	adc_val=adc_val & 0x3fff;
	final_vol=(float)adc_val;
	final_vol=(final_vol/16384)*1.2235; /*Vref=1.2235V*/
	printf("\nADC Value=%2.4f Volts", final_vol);
	delay(1000);
		}

}