// ----------------- Include any necessary libraries here -----------------------
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "univ_logo.h"

// ---------------------- IO & peripherals Constants ----------------------------
#define SCREEN_WIDTH 128 // OLED width,  in pixels
#define SCREEN_HEIGHT 64 // OLED height, in pixels
#define POT_PIN       35 // Potentiometer is connected to GPIO 34 (Analog ADC1_CH6) 

// ---------------------------- Object creation ---------------------------------
// create an OLED display object connected to I2C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);



// -------------------------- Functions definition ------------------------------
// function that displays a bitmap on oled display
void display_bitmap(Adafruit_SSD1306 &disp, const unsigned char* image, 
                          unsigned int height, unsigned int width) {
  disp.clearDisplay();
  disp.setCursor(0, 0);
  disp.drawBitmap(32, 0, image, height, width, WHITE);
  disp.display();
  delay(2000);
  disp.clearDisplay();
  disp.display();
}

// ------------------------------ Main program ---------------------------------

// this "setup" function is executed only once to configure the IO and peripherals
void setup() {
  // Initialize oled interface
  Serial.begin(115200);
  // Initalize analog inputs
  pinMode(POT_PIN, INPUT);
  // initialize OLED display with I2C address 0x3C
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("failed to start SSD1306 OLED"));
    while (1);
  }
  // wait two seconds for initializing
  delay(2000);
  // set text size          
  display.setTextSize(1);
  // set text color         
  display.setTextColor(WHITE);
  // clear display
  display.clearDisplay();  
  // display medea university logo
  display_bitmap(display, univ_image, IMG_H, IMG_W);
}

// this "loop" function is executed indefinetly (in an infinite loop / superloop)
void loop() {
  // read input voltage
  int adc_value = analogRead(POT_PIN);           // result is in 12bits format (0 - 4095)
  float analog_value = (float)adc_value/4095.0 * 3.3;   // convert analog reading to a voltage (0 - 3.3V)
  // display the result on serial monitor (with uart interface)
  Serial.println("Pot = " + String(analog_value,2) + " V");
  // display the result on oled display
  display.clearDisplay();                                    // clear display
  display.setCursor(0, 2);                                   // set position to display (x,y)
  display.print("Pot = " + String(analog_value,2) + " V");   // set text
  display.display();                                         // display on OLED
  // get a new reading and display after waiting 100ms
  delay(100);                                                
  // repeat form the first instruction of the loop function
}