// Author     : zufrizalyordan@gmail.com
// Description: Displays potentiometer value via arduino to oled 128x32

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define ANALOG_IN_PIN A0

// 0.96 inch
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// 0.91 inch
// #define SCREEN_HEIGHT 32 // OLED display height, in pixels

int sensorValue = 0;
// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// Floats for ADC voltage & Input voltage
float adc_voltage = 0.0;
float in_voltage = 0.0;
 
// Floats for resistor values in divider (in ohms)
float R1 = 30000.0;
float R2 = 7500.0; 
 
// Float for Reference Voltage
float ref_voltage = 3.3;
 
// Integer for ADC value
int adc_value = 0;

void setup() {
  Serial.begin(115200);

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }

  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.setTextSize(1);
  display.println("Hello!");
  display.display();
  delay(1500);
}

void loop() {
  display.clearDisplay();
  adc_value = analogRead(ANALOG_IN_PIN);
  // Determine voltage at ADC input
  adc_voltage  = (adc_value * ref_voltage) / 1024.0; 
   
  // Calculate voltage at divider input
  in_voltage = adc_voltage / (R2/(R1+R2)) ; 
   
  display.setCursor(0,0);
  display.println("ADC: " + String(adc_value));
  display.println("Vadc: " + String(adc_voltage));
  display.println("Vin: " + String(in_voltage));
  display.display();

  int mappedValue = map(adc_value, 0, 1023, 0, ref_voltage);
  display.setCursor(0,24);
  display.println("Mapped: " + String(mappedValue));
  display.display();

  int brightness = map(adc_value, 0, 1023, 0, 255);
  analogWrite(LED_BUILTIN, brightness);

  delay(1000);
}