Strobe detector

//DISPLAY INI start
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define NUMFLAKES 10
#define XPOS 0
#define YPOS 1
#define DELTAY 2


#if (SSD1306_LCDHEIGHT != 64)
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif

//DISPLAY INI END



byte photoled = 1; //photoresistor or photodiode

int chart[128]; //128 reads will be displayed on an OLED which is 128px wide

byte x = 0; //counts 0 to 127 to fill the screen
int maxVal; //max value, for chart scaling
int minVal; //like above but min
long oldmillis; //for frequency calculation
float hejtow_na_floaty = 1; //shoutout to wykop.pl comment, which did not like my use of floats ;)

void setup() {

  Serial.begin(9600);

  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3D (for the 128x64)
  // init done

  // Show image buffer on the display hardware.
  // Since the buffer is intialized with an Adafruit splashscreen
  // internally, this will display the splashscreen.
  display.clearDisplay();// Clear the buffer.
  display.setTextSize(1); //setup for the text
  display.setTextColor(WHITE);

}

// the loop routine runs over and over again forever:
void loop() {


int light = analogRead(photoled); //read the photoresistor, simple voltage divider with 1 megaohm resistor. I wanted to use an LED as photodiode, but photoresistor gave much better signal and was fast enough




if (light > maxVal){ //hunt for the max value and min value
  maxVal = light;
}

if (light < minVal){
  minVal = light;
}

chart[x] = light; //put current read to an array

x++;



if (x == 128){ //time to display the chart!
  display.setCursor(0,0);  // reset cursor
  float Hz; //calculations for frequency of the screen
  Hz = 1000/(millis() - oldmillis);
  display.print(Hz);
  display.print("Hz");
  /*display.print("Max:");
  display.println(maxVal);
  display.print("Min:");
  display.println(minVal);*/
  float gap = maxVal - minVal; //this is for scaling, finding the gap
  float scale = gap / 64;
  float tempchart;
  for (int i = 0; i < 128; i++){
    chart[i] = chart[i] - minVal; //zeroing to min value
    tempchart = chart[i] / scale;//and scaling
    chart[i] = tempchart;

    if (i == 0){}
    else{

    display.drawLine(i, 63-chart[i], i-1, 63 - chart[i-1],1); //drawing line. I just ignore the exception for i = 0, works fine still.
    }
    //display.drawPixel(i, 63-chart[i], 1);
  }


 display.display();
 x = 0; //tidying up for the next go
 maxVal = 0;
 minVal = 1023;
 display.clearDisplay();
 delay(500); //wait half a second, let me lookm at the result
 oldmillis = millis();
}



//delayMicroseconds(1); //may be used to slow down the polling frequency


}