// Including the required Arduino libraries for MAX7219 Display and Ultrasonic sensor
#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>
#include <NewPing.h>

//Ultrasonic sensor pin settings
#define TRIGGER_PIN  7  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN     6  // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 1000 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

#define HARDWARE_TYPE MD_MAX72XX::FC16_HW

// Defining size, and output pins
#define MAX_DEVICES 4
#define CS_PIN 3

// Create a new instance of the MD_Parola class with hardware SPI connection
MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);

void setup() 
{
  Serial.begin(9600); // Open serial monitor at 115200 baud to see ping results.
  // Intialize the object
  myDisplay.begin();
  // Set the intensity (brightness) of the display (0-15)
  myDisplay.setIntensity(1);
  // Clear the display
  myDisplay.displayClear();
}

void loop() {
  myDisplay.setTextAlignment(PA_CENTER);
  Serial.print(sonar.ping_cm()); // Send ping, get distance in cm and print result (0 = outside set distance range)
  Serial.println("cm"); // check serial monitor
  
  if(sonar.ping_cm() < 5 && sonar.ping_cm() > 0) // condition to tell if the object is too close.
  {
    myDisplay.print("STOP");
  }
  else{
    myDisplay.print("");
  } 
  delay(50); 
}