adc 测量子系统

        #include <stdio.h>
        #include <stdlib.h>
        #include <fcntl.h>
        #include <unistd.h>
        #include <math.h> 

        char iiotype[16][32] = {
                'in_voltage1_raw',
                'in_voltage2_raw',
        };
              

      
       
        // return = 0: voltage value from AIN1, unit: mV
        // < 0: failed
        int read_AIN1(float *fvoltage)
        {
                int value, ret = 0;
                char filename[80];
                FILE *fp;
                char buf[20];

                sprintf( filename, '/sys/bus/iio/devices/iio:device0/%s', iiotype[0]);
                fp = fopen(filename, 'rt' );
                if( fp==NULL )
                {
                        printf('open %s fail! ', filename);
                        *fvoltage = 0.0;
                        ret = -1;
                        return ret;
                }
                fread( buf, 1, sizeof(buf), fp );
                fclose(fp);

                // convert to integer
                sscanf( buf, '%d', &value );
                *fvoltage = 0.8 * value;
                return ret;
        }

　　　// return = 0: voltage value from AIN2, unit: mV
        // < 0: failed
        int read_AIN2(float *fvoltage)
        {
                int value, ret = 0;
                char filename[80];
                FILE *fp;
                char buf[20];

                sprintf( filename, '/sys/bus/iio/devices/iio:device0/%s', iiotype[1]);
                fp = fopen(filename, 'rt' );
                if( fp==NULL )
                {
                        printf('open %s fail! ', filename);
                        *fvoltage = 0.0;
                        ret = -1;
                        return ret;
                }
                fread( buf, 1, sizeof(buf), fp );
                fclose(fp);

                // convert to integer
                sscanf( buf, '%d', &value );
                *fvoltage = 0.8 * value;
                return ret;
        }

      
        int main(int argc, char** argv)
        {
                int ret = 0;
                float fvalue;

            
                // read AIN1
                ret = read_AIN1(&fvalue);
                if(ret < 0)
                {
                        return ret;
                }
                printf('AIN1 = %.2f mV ', fvalue);

                // read AIN2
                ret = read_AIN2(&fvalue);
                if(ret < 0)
                {
                        return ret;
                }
    
        }