此段代碼沒有ds18b20的id設置 ，只是實現(xiàn)了一個簡單的溫度輸出。對ds18b20理解足夠，重點在如何看到datesheet的時序圖，以及功能的如何實現(xiàn)步驟。

#include //支持printk輸出

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define DEVICE_NAME "DS18B20"

#define DS18B20_MAJOR 231

#define DQ S3C2410_GPG0

#define CLK S3C2410_GPB0

#define W1 S3C2410_GPH9

#define W2 S3C2410_GPE10

#define W3 S3C2410_GPH7

#define AB S3C2410_GPB4

#define OUT S3C2410_GPIO_OUTPUT

#define IN S3C2410_GPIO_INPUT

#define HIGH 1

#define LOW 0

//定義DS18B20ROM指令

#define DS18B20_ReadROM 0x33 //讀ROM

#define DS18B20_MatchROM 0x55 //匹配ROM

#define DS18B20_SkipROM 0xCC //跳過ROM

#define DS18B20_SearchROM 0xF0 //搜索ROM

#define DS18B20_AlarmROM 0xEC //報警搜索

//定義DS18B20存儲器操作命令

#define DS18B20_WriteSCR 0x4E //寫暫存存儲器

#define DS18B20_ReadSCR 0xBE //讀暫存存儲器

#define DS18B20_CopySCR 0x48 //復制暫存存儲器

#define DS18B20_ConvertTemp 0x44 //溫度變換

#define DS18B20_RecallEP 0xB8 //重新調出

#define DS18B20_ReadPower 0xB4 //讀電源

static char devicecount=0; //計數(shù)器，防止被多個人多次打開

unsigned char DS18B20_Init(void)

{

s3c2410_gpio_cfgpin(DQ,OUT);

s3c2410_gpio_setpin(DQ,LOW);

udelay(700);

s3c2410_gpio_cfgpin(DQ,IN);

udelay(60);

udelay(240);

return 0;

}

unsigned char DS18B20_readbit(void)

{

unsigned char bit;

s3c2410_gpio_cfgpin(DQ,OUT);

s3c2410_gpio_setpin(DQ,LOW);

udelay(15);

s3c2410_gpio_cfgpin(DQ,IN);

bit=s3c2410_gpio_getpin(DQ);

udelay(45);

return bit;

}

unsigned char DS18B20_readbyte(void)

{

unsigned char i,j,dat;

dat=0;

for(i=1;i<=8;i++)

{

j=DS18B20_readbit();

dat=(j<<7)|(dat>>1);

}

return dat;

}

void DS18B20_writebyte(unsigned char dat)

{

unsigned int i;

unsigned char j;

for(i=1;i<=8;i++)

{

j=dat&0x01;

dat=dat>>1;

if(j)

{

s3c2410_gpio_cfgpin(DQ,OUT);

s3c2410_gpio_setpin(DQ,LOW);

udelay(10);

s3c2410_gpio_setpin(DQ,HIGH);

udelay(45);

}

else

{

s3c2410_gpio_cfgpin(DQ,OUT);

s3c2410_gpio_setpin(DQ,LOW);

udelay(60);

s3c2410_gpio_setpin(DQ,HIGH);

}

}

}

unsigned short DS18B20_tmperature(void)

{

unsigned int a,b;

unsigned short tmp;

DS18B20_Init();

DS18B20_writebyte(DS18B20_SkipROM);

DS18B20_writebyte(DS18B20_ConvertTemp);

DS18B20_Init();

DS18B20_writebyte(DS18B20_SkipROM);

DS18B20_writebyte(DS18B20_ReadSCR);

a=DS18B20_readbyte();

b=DS18B20_readbyte();

tmp=b;

tmp=tmp<<8;

tmp=tmp|a;

return tmp;

}

void display(unsigned char dat)

{

unsigned char i;

for(i=1;i<=8;i++)

{

s3c2410_gpio_cfgpin(CLK,OUT);

s3c2410_gpio_setpin(CLK,LOW);

s3c2410_gpio_cfgpin(AB,OUT);

s3c2410_gpio_setpin(AB,dat&0x01);

s3c2410_gpio_setpin(CLK,HIGH);

dat>>=1;

}

udelay(700);

}

static int DS18B20_write(struct file *file, const char __user *buffer, size_t count, loff_t * ppos)

{

unsigned char i,a[3];

unsigned char table[]={0x3f,0x06,0x5b,0x4f, 0x66,0x6d,0x7d,0x07,0x7f,0x6f};//共陰

unsigned char table1[]={0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,0x87,0xff,0xef,0x40};

copy_from_user(a,buffer,sizeof(a));

for(i=100;i--;i>0)

{

s3c2410_gpio_cfgpin(W1,OUT);

s3c2410_gpio_setpin(W1,LOW);

display(table[a[0]]);

s3c2410_gpio_cfgpin(W1,IN);

s3c2410_gpio_cfgpin(W2,OUT);

s3c2410_gpio_setpin(W2,LOW);

display(table1[a[1]]);

s3c2410_gpio_cfgpin(W2,IN);

s3c2410_gpio_cfgpin(W3,OUT);

s3c2410_gpio_setpin(W3,LOW);

display(table[a[2]]);

s3c2410_gpio_cfgpin(W3,IN);

}

return 0;

}

static int DS18B20_read(struct file *filp, char __user *buffer, size_t count, loff_t *ppos)

{

unsigned short tmp;

tmp=DS18B20_tmperature();

printk("tmperature = %d\n",tmp);

if(tmp<600)

copy_to_user(buffer,&tmp,sizeof(tmp));

return 0;

}

static int DS18B20_open(struct inode *inode,struct file *file)//3

{

if(devicecount >0) return -ERESTARTSYS;

printk("device open : success\n");

devicecount++;

return 0;

}

static int DS18B20_release(struct inode *inode, struct file *filp)//5

{

devicecount--;

printk("device release\n");

return 0;

}

static int DS18B20_ioctl(struct inode *inode,struct file *file,unsigned int cmd,unsigned long arg)//4

{

printk("*************This is the first driver----hello,welcome to embedded world *************\n");

return 0;

}

static struct file_operations DS18B20_fops = {//2_1

.owner = THIS_MODULE,

.ioctl = DS18B20_ioctl,

.write = DS18B20_write,

.read = DS18B20_read,

.open = DS18B20_open,

.release = DS18B20_release,

};

static int __init DS18B20_init(void)//2_0

{

int ret;

ret = register_chrdev(DS18B20_MAJOR, DEVICE_NAME, &DS18B20_fops);

if (ret < 0) {

printk(DEVICE_NAME " can't register major number\n");

return ret;

}

printk(DEVICE_NAME " initialized\n");

return 0;

}

static void __exit DS18B20_exit(void)//6

{

unregister_chrdev(DS18B20_MAJOR, DEVICE_NAME);

}

module_init(DS18B20_init); //1

module_exit(DS18B20_exit);//6

MODULE_AUTHOR("Yink_Liu");

MODULE_DESCRIPTION("A simple Hello World Moudle");

MODULE_ALIAS("a simple module");

MODULE_LICENSE("Dual BSD/GPL");