2410自帶了8個(gè)ad通道，10bit，500ksps。在網(wǎng)上查了資料，很少有人用它做ad轉(zhuǎn)換的，原因是精度不高。不過(guò)對(duì)于一些要求不是很高的地方，還是值得一用。
在/kernel/drivers/char中已經(jīng)有了ad不完整的驅(qū)動(dòng)，基本框架搭好了，只要加上文件系統(tǒng)那部分就可以直接使用了。使用時(shí)一定要在Vref上加上電壓，否則ad就不工作了?，F(xiàn)在就把驅(qū)動(dòng)和應(yīng)用程序貼出來(lái)，供大家參考學(xué)習(xí)。
應(yīng)用程序的作用是要測(cè)量的通道號(hào)告訴驅(qū)動(dòng)，驅(qū)動(dòng)得到通道號(hào)經(jīng)過(guò)ad轉(zhuǎn)換后將數(shù)字量傳給應(yīng)用程序。
驅(qū)動(dòng)程序：
/*
* s3c2410-adc.c
*
* S3C2410 ADC 
*  exclusive with s3c2410-ts.c
*/
#include linux/config.h>
#include linux/module.h>
#include linux/kernel.h>
#include linux/init.h>
#include linux/sched.h>
#include linux/irq.h>
#include linux/delay.h>
#include asm/hardware.h>
#include asm/semaphore.h>
#include asm/uaccess.h>
#include asm/io.h> 
#define DEVICE_NAME   "s3c2410-adc"
#define ADCRAW_MINOR   1
#define ADC_WRITE(ch, prescale)  ((ch)<<16|(prescale))
#define ADC_WRITE_GETCH(data)  (((data)>>16)&0x7)   //得到通道號(hào)
#define ADC_WRITE_GETPRE(data)  ((data)&0xff)      //得到轉(zhuǎn)換的比例因子 
static int adcMajor = 0; 
typedef struct {
struct semaphore lock;
wait_queue_head_t wait;
int channel;
int prescale;
}ADC_DEV; 
static ADC_DEV adcdev; 
#define START_ADC_AIN(ch, prescale) \
do{ \
ADCCON = PRESCALE_EN | PRSCVL(prescale) | ADC_INPUT((ch)) ; \
ADCCON |= ADC_START; \
}while(0) 
static void adcdone_int_handler(int irq, void *dev_id, struct pt_regs *reg)
{
wake_up(&adcdev.wait);
} 
static ssize_t s3c2410_adc_write(struct file *file, const char *buffer, size_t count, loff_t * ppos)
{
int data; 
if(count!=sizeof(data)){
printk("the size of  input data must be %d\n", sizeof(data));
return 0;
}
copy_from_user(&data, buffer, count);
adcdev.channel=ADC_WRITE_GETCH(data);
adcdev.prescale=ADC_WRITE_GETPRE(data);
DPRINTK("set adc channel=%d, prescale=0x%x\n", adcdev.channel, adcdev.prescale);
return count;
} 
static ssize_t s3c2410_adc_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{
int ret = 0;
if (down_interruptible(&adcdev.lock))
return -ERESTARTSYS;
START_ADC_AIN(adcdev.channel, adcdev.prescale);
interruptible_sleep_on(&adcdev.wait);
printk("in read channel=%d\n",adcdev.channel);
ret = ADCDAT0;
printk("ADCDAT0=%x\n",ADCDAT0);
while((ADCCON & 0x80)!=1)
udelay(100);
ret &= 0x3ff;
copy_to_user(buffer, (char *)&ret, sizeof(ret));
up(&adcdev.lock);
return sizeof(ret);
} 
static int s3c2410_adc_open(struct inode *inode, struct file *filp)
{
init_MUTEX(&adcdev.lock);
init_waitqueue_head(&(adcdev.wait)); 
adcdev.channel=0;
adcdev.prescale=0xff; 
MOD_INC_USE_COUNT;
printk("adc opened!\n");
return 0;
} 
static int s3c2410_adc_release(struct inode *inode, struct file *filp)
{
MOD_DEC_USE_COUNT;
printk( "adc closed\n");
return 0;
} 

static struct file_operations s3c2410_fops = {
owner:THIS_MODULE,
open:s3c2410_adc_open,
read:s3c2410_adc_read,
write:s3c2410_adc_write,
release:s3c2410_adc_release,
}; 
#ifdef CONFIG_DEVFS_FS
static devfs_handle_t devfs_adc_dir, devfs_adcraw;
#endif 
int __init s3c2410_adc_init(void)
{
int ret; 
/* normal ADC */
ADCTSC = 0;
ret = request_irq(IRQ_ADC_DONE, adcdone_int_handler, SA_INTERRUPT, DEVICE_NAME, NULL);
if (ret) {
return ret;
} 
ret = register_chrdev(0, DEVICE_NAME, &s3c2410_fops);
if (ret < 0) {
printk(DEVICE_NAME " can't get major number\n");
return ret;
}
adcMajor=ret; 
#ifdef CONFIG_DEVFS_FS
devfs_adc_dir = devfs_mk_dir(NULL, "adc", NULL);
devfs_adcraw = devfs_register(devfs_adc_dir, "0raw", DEVFS_FL_DEFAULT,
adcMajor, ADCRAW_MINOR, S_IFCHR | S_IRUSR | S_IWUSR, &s3c2410_fops, NULL);
#endif
printk (DEVICE_NAME"\tinitialized\n");
printk ("initialized\n"); 
printk("inilized ADCDAT0=%x\n",ADCDAT0);
printk("inilized ADCCON=%x\n",ADCCON);
return 0;
} 
module_init(s3c2410_adc_init); 
#ifdef MODULE
void __exit s3c2410_adc_exit(void)
{
#ifdef CONFIG_DEVFS_FS
devfs_unregister(devfs_adcraw);
devfs_unregister(devfs_adc_dir);
#endif
unregister_chrdev(adcMajor, DEVICE_NAME); 
free_irq(IRQ_ADC_DONE, NULL);
} 
module_exit(s3c2410_adc_exit);
MODULE_LICENSE("GPL");
#endif 
應(yīng)用程序：
#include stdio.h>
#include unistd.h>
#include sys/types.h>
#include sys/ipc.h>
#include sys/ioctl.h>
#include fcntl.h> 
#define ADC_DEV"/dev/adc/0raw"
#define ADC_WRITE(ch, prescale)((ch)<<16|(prescale))
#define ADC_WRITE_GETCH(data)(((data)>>16)&0x7)   //得到通道號(hào)
#define ADC_WRITE_GETPRE(data)((data)&0xff)      //得到轉(zhuǎn)換的比例因子 
static int get(int channel)
{
int PRESCALE=0XFF;
int data=ADC_WRITE(channel, PRESCALE);
write(adc_fd, &data, sizeof(data));
read(adc_fd, &data, sizeof(data));
return data;
} 
main()
{
int i;
int fd;
float d;
void * retval;
   
if((fd=open(ADC_DEV, O_RDWR))<0)
{
printf("Error opening %s adc device\n", ADC_DEV);
return -1;
}
for(i=0; i<=7; i++)
{
d=((float)get(i)*3.3)/1024.0;
printf("a[%d]=%8.4f\n",i,d);
}
}