adc使用问题

• wjh

  Posts: 16

  Joined: 2025-08-06 2:29

  2025-08-22 7:42

  使用官网这个例程，我改了一下adc通道，发现读的adc好像永远是第一次的值，没有实时改变。
  
  后面把fopen和fclose放到循环里面才实时变化，是循环调用的fseek是没起作用吗？
  

  Code: Select all

  #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <fcntl.h>
  
  int main() {
      printf("Press Ctrl+C to quit\n");
      const char *adc_dir = "/sys/bus/iio/devices/iio:device0";
  
      char in_voltage2_raw_path[256];
      char in_voltage_scale_path[256];
  
      sprintf(in_voltage2_raw_path, "%s/in_voltage2_raw", adc_dir);
      sprintf(in_voltage_scale_path, "%s/in_voltage_scale", adc_dir);
  
      FILE *scale_file = fopen(in_voltage_scale_path, "r");
      FILE *in2_raw_file = fopen(in_voltage2_raw_path, "r");
  
      while (1) {
  
          char buffer[32];
  
          fseek(scale_file, 0, SEEK_SET);
          fseek(in2_raw_file, 0, SEEK_SET);
  
          if (scale_file && in2_raw_file) {
              fgets(buffer, sizeof(buffer), scale_file);
              float scale = strtof(buffer, NULL);
  
              fgets(buffer, sizeof(buffer), in2_raw_file);
              int in2_raw_value = atoi(buffer);
              float in2_voltage = (in2_raw_value * scale) / 1000.0;
  
              printf("IN2 Voltage: %.6f V\n", in2_voltage);
          }
  
          sleep(1);
      }
  
      fclose(scale_file);
      fclose(in2_raw_file);
  
      return 0;
  }

  我改成这样就行了

  Code: Select all

  #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <fcntl.h>
  
  int main() {
      printf("Press Ctrl+C to quit\n");
      const char *adc_dir = "/sys/bus/iio/devices/iio:device0";
  
      char in_voltage2_raw_path[256];
      char in_voltage_scale_path[256];
  
      sprintf(in_voltage2_raw_path, "%s/in_voltage2_raw", adc_dir);
      sprintf(in_voltage_scale_path, "%s/in_voltage_scale", adc_dir);
  
  
      while (1) {
          FILE *scale_file = fopen(in_voltage_scale_path, "r");
          FILE *in2_raw_file = fopen(in_voltage2_raw_path, "r");
  
          char buffer[32];
  
          fseek(scale_file, 0, SEEK_SET);
          fseek(in2_raw_file, 0, SEEK_SET);
  
          if (scale_file && in2_raw_file) {
              fgets(buffer, sizeof(buffer), scale_file);
              float scale = strtof(buffer, NULL);
  
              fgets(buffer, sizeof(buffer), in2_raw_file);
              int in2_raw_value = atoi(buffer);
              float in2_voltage = (in2_raw_value * scale) / 1000.0;
  
              printf("IN2 Voltage: %.6f V\n", in2_voltage);
          }
  
          fclose(scale_file);
          fclose(in2_raw_file);
  
          sleep(1);
      }
  
      return 0;
  }

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