switch(conv_direction)
{
case EConvType_Raw_to_Scale:
result = ((input * 3.0 * mV_mul)/multiplier);
break;
case EConvType_Scale_to_Raw:
result = (input/(3.0 * mV_mul))*multiplier;
break;
default:
printf("Convertion type incorrect... Doing no conversion\n");
// intentional no break;
case EConvType_None:
result = input;
break;
}

return result;
}

float conv_voltage_ext_ch(float input, enum EConvType conv_direction)
{
float result=0;

switch(conv_direction)
{
case EConvType_Raw_to_Scale:
result = ((input * mV_mul)/multiplier);
break;
case EConvType_Scale_to_Raw:
result = (input/mV_mul)*multiplier;
break;
default:
printf("Convertion type incorrect... Doing no conversion\n");
// intentional no break;
case EConvType_None:
result = input;
break;
}

return result;
}

float conv_temperature(float input, enum EConvType conv_direction)
{
float result=0;

switch(conv_direction)
{
case EConvType_Raw_to_Scale:
result = ((input * 503.975)/multiplier) - 273.15;
break;
case EConvType_Scale_to_Raw:
result = (input + 273.15)*multiplier/503.975;
break;
default:
printf("Conversion type incorrect... Doing no conversion\n");
// intentional no break;
case EConvType_None:
result = input;
break;
}

return result;
}

void get_iio_node()
{
struct dirent **namelist;
int i,n;
char value=0;
int fd = -1;
char upset[20];
float raw_data=0;
float true_data=0;
int offset=0;
int currpos;

n = scandir(SYS_PATH_IIO, &namelist, 0, alphasort);

for (i=0; i < n; i++)
{
sprintf(gNodeName,"%s/%s", SYS_PATH_IIO, namelist[i]->d_name);

fd = open(gNodeName, O_RDWR );

if(strstr(gNodeName,"temp"))
{
if(strstr(gNodeName,"raw"))
{
offset=0;
while(offset<5)
{
lseek(fd,offset,SEEK_SET);
read(fd,&value,sizeof(char));
upset[offset]=value;
offset++;
}
upset[offset]='\0';
raw_data=atoi(upset);
true_data=conv_temperature(raw_data, EConvType_Raw_to_Scale);
printf("%s is %f cent\n",namelist[i]->d_name,true_data);
}
}
else if(strstr(gNodeName,"voltage"))
{
if(strstr(gNodeName,"raw"))
{
offset=0;
while(offset<5)
{
lseek(fd,offset,SEEK_SET);
read(fd,&value,sizeof(char));
upset[offset]=value;
offset++;
}
upset[offset]='\0';
raw_data=atoi(upset);
true_data=conv_voltage(raw_data, EConvType_Raw_to_Scale);
printf("%s is %f mv\n",namelist[i]->d_name,true_data);
}
}
close(fd);

}
}

int main(int argc, char *argv[])
{
get_iio_node();
return 0;
}

在編寫這段代碼時(shí)遇到好幾個(gè)問題，首先用read函數(shù)取值取到的其實(shí)是文件中ASCII碼字符，沒有什么好辦法只好改成一位一位讀取存入字符串然后調(diào)用atoi函數(shù)轉(zhuǎn)換為int數(shù)字。其次，用lseek函數(shù)獲取文件大小時(shí)得到的值都為4096，但是這些文件并不是目錄，不知道為何大小都顯示的是Linux最基本的文件塊大小，最后只好投機(jī)取巧根據(jù)每個(gè)文件中的數(shù)字位數(shù)進(jìn)行取值，例如temp和vcc這些文件只有4位，那么就從文件中讀4位。最后輸出結(jié)果如下：

上圖中溫度為39度，和實(shí)際情況差不多。至此XADC驅(qū)動(dòng)告一段落。