The Circuit:

The Code:

  1 /**********************************************************************
  2 * Filename    : Softlight.cpp                          
  3 * Description : Use potentiometer to control LED       
  4 * Author      : www.freenove.com                       
  5 * modification: 2020/03/07                             
  6 **********************************************************************/
  7 #include <wiringPi.h>                                  
  8 #include <stdio.h>
  9 #include <softPwm.h>                                   
 10 #include <ADCDevice.hpp>                               
 11                   
 12 #define ledPin 0  
 13                   
 14 ADCDevice *adc;                                         // Define an ADC Device class object
 15                   
 16 int main(void){   
 17     adc = new ADCDevice();                              //Create a link to the Device
 18     int   adcValue;                                     //Stores the a hardware value
 19     float voltage;                                      //Stores the voltage
 20     printf("Program is starting ... \n");              
 21                   
 22     //are we using the pcf8591                         
 23     if(adc->detectI2C(0x48)){                          
 24         delete adc;                                     // Free previously pointed memory
 25         adc = new PCF8591();                            // If we are using it, create it
 26     }             
 27     //are we using the ads7830                         
 28     else if(adc->detectI2C(0x4b)){                     
 29         delete adc;                                     // Free previously pointed memory
 30         adc = new ADS7830();                            // If we are using it, create it.
 31     }             
 32     //if we have nothing                               
 33     else{         
 34         printf("No correct I2C address found, \n"      
 35         "Please use command 'i2cdetect -y 1' to check the I2C address! \n"
 36         "Program Exit. \n");                           
 37         return -1;
 38     }             
 39     wiringPiSetup();                                    //setup the board
 40     softPwmCreate(ledPin,0,100);                       
 41     while(1){     
 42         adcValue = adc->analogRead(0);                  // read analog value for voltage
 43         softPwmWrite(ledPin,adcValue*100/255);          // Mapping to PWM duty cycle
 44         voltage  = (float)adcValue / 255.0 * 3.3;       // Calculate voltage
 45         printf("ADC value : %d  ,\tVoltage : %.2fV\n",adcValue,voltage);
 46         delay(30);                                                                                          
 47     }             
 48     return 0;     
 49 }

This project requires a few things to be done before the program can be ran. First I had to have the i2c interface enabled on the PI, then I had install the i2c tools, and finally I had to build the ADCDevice library. After doing all of this the program will run. Otherwise the circuit requires a potentiometer, the ADC module (I used the PCF8591) two 10k ohm resistors, one 220 ohm resistor, and an LED. When ran the LED will start at no brightness and grow brighter as I adjust the potentiometer. I also added more comments to the code to to describe the conditionals used, I aligned/edited to comments to make them read better, and I moved the declaration of variables to outside the while loop.