/*
Wokwi | questions
MCP23017 assistance

Dimitar — March 31, 2025 at 11:17 PM
Hi guys im new to this and I wanted to simulate a MCP23017 and i made this project:
 https://wokwi.com/projects/426989472514014209
I used a custom chip i found just by searching mcp23017 and nothing is reacting. 
Please help! THANKS
*/

#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>
#include "MCP23017.h"  // cool custom library

#define OLED_ADDR 0x3C
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
MCP23017 mcp;

const uint8_t MCP_PIN = 1;       // GPA0
const uint8_t ARDUINO2 = 2; // setting output

void setup() {
  Serial.begin(9600);
  Wire.begin();

  // Initialize OLED
  display.setRotation(2);
  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    Serial.println(F("OLED failed"));
    while (1);
  }

  
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Hello :)"); //hi future me
  display.display();

  // Setup MCP23017 at address 0x20
  mcp.begin(0); // address 0 (defined by grounding all A pins)
  mcp.pinMode(MCP_PIN, OUTPUT); //output

  // Setup Arduino D2 to read from MCP output
  pinMode(ARDUINO2, INPUT);

  Serial.println("Setup done.");
}

void loop() {
  // Toggle MCP pin HIGH
  mcp.digitalWrite(MCP_PIN, HIGH);
  delay(1000);
  Serial.print("MCP23017 GPA0: HIGH | Arduino D2 reads: ");
  Serial.println(digitalRead(ARDUINO2));

  // Toggle MCP pin LOW
  mcp.digitalWrite(MCP_PIN, LOW);
  delay(1000);
  Serial.print("MCP23017 GPA0: LOW  | Arduino D2 reads: ");
  Serial.println(digitalRead(ARDUINO2));

  Serial.println("I------------------------I");
}