一、实验平台:开发板fs2410,采用三星s3c2410的CPU,无操作系统。
二、实现功能:调节开发板上的可变电阻,在串口中实时显示AD转换器的值。
三、实验原理:
S3C2410A 的具有8通道模拟输入的10位CMOS 模数转换器(ADC)。它将输入的模拟信号转换为10位的二进制数字代码。然后从对应的寄存器中读出转换后的值,并通过串口输出。
用可调电阻模拟AD转换器的输入,开发板上蓝色小部件,如图:
四、实验现象:
五、实验总结:
因为是10位的AD转换器,所以转换后的值的范围应为0x000—0x3ff。
六、示例代码:
/*s3c2410.h*/
#ifndef _S3C2410_H_
#define _S3C2410_H_
#define ULCON0 (*(volatile unsigned long *)0x50000000)
#define UCON0 (*(volatile unsigned long *)0x50000004)
#define UFCON0 (*(volatile unsigned long *)0x50000008)
#define UMCON0 (*(volatile unsigned long *)0x5000000C)
#define UTRSTAT0 (*(volatile unsigned long *)0x50000010)
#define UTXH0 (*(volatile unsigned long *)0x50000020)
#define URXH0 (*(volatile unsigned long *)0x50000024)
#define UBRDIV0 (*(volatile unsigned long *)0x50000028)
#define GPHCON (*(volatile unsigned long *)0x56000070)
#define GPHDAT (*(volatile unsigned long *)0x56000074)
#define GPHUP (*(volatile unsigned long *)0x56000078)
#define ADCCON (*(volatile unsigned long *)0x58000000)
#define ADCDAT0 (*(volatile unsigned long *)0x5800000c)
#define GPH2_out (1<<5)
#define GPH3_in (1<<7)
void putc(char ch);
char getc(void);
void putstr(char *str);
#endif
/*串口UART0*/
#include "s3c2410.h"
void putc(char ch)
{
while(!(UTRSTAT0 & 0X2));
UTXH0 = ch;
}
char getc(void)
{
while(!(UTRSTAT0 & 0X1));
return URXH0;
}
void putstr(char *str)
{
while(*str != '\0'){
if(*str == '\n'){
putc('\n');
putc('\r');
}
else
putc(*str);
str++;
}
}
/*ADC.c*/
#include "s3c2410.h"
void wait(unsigned long dly)
{
for(;dly>0;dly--);
}
void atoi(unsigned long x)
{
unsigned long temp;
int i,flag = 0;
char data[4];
for(i=0;i<4;i++)
data[i] = '\0';
for(i=0;i<3;i++){
temp = (x>>4*i)&0xf;
if(temp < 10)
data[2-i] = '0'+temp;
else if(temp <= 0xf)
data[2-i] = 'a'+temp-10;
}
putstr(" Value of AIN0 is 0x");
putstr(data);
putstr("\r");
}
int main(void)
{
GPHCON = GPH2_out|GPH3_in; //串口初始化
GPHUP = 0X0C;
UFCON0 &= 0;
UMCON0 &= ~(1<<4);
ULCON0 = 0X3;
UCON0 = 0X5;
UBRDIV0 = ((int)(50000000/115200/16)-1);
ADCCON = 0x4c41; //ADC初始化
putstr("\nThis is ADC test:\n");
unsigned long temp = 0;
while(1){
while((ADCCON&(1<<15)) == 0);
temp = ADCDAT0&0x3ff;
atoi(temp);
ADCCON = 0x4c41; //ADC初始化
wait(100000);
}
return 0;
}