Calculator (Arduino)

A calculator built with an Arduino that supports:

• Addition, subtraction, multiplication, division
• Whole and decimal numbers
• Order of operations: * and / first, then + and -

This repo contains the Arduino sketch and a presentation.

---

What’s in this repository

• final_code.ino - Arduino code
• Calculator – Arduino Project.pptx - project presentation

---

Wiring (pin map used in the code)

Rotary encoder

• CLK -> D10
• DT -> D9
• SW -> D8 (button uses INPUT_PULLUP)

Keypad (4x4)

• Rows -> D0, D1, D2, D3
• Cols -> D4, D5, D6, D7

Key layout in code:

• Row1: 1 2 3 +
• Row2: 4 5 6 -
• Row3: 7 8 9 .
• Row4: * 0 / =

LCD (I2C)

• Address: 0x27
• Uses I2C pins (SDA/SCL) for your board (Uno: A4/A5)

IMPORTANT: Because the keypad uses D0/D1, you should not rely on Serial Monitor on an Arduino Uno (D0/D1 are the UART pins).

---

How to run it

1. Install Arduino IDE.
2. Install required libraries (Arduino Library Manager):
   • Keypad (for the 4x4 keypad)
   • LiquidCrystal_I2C (for the I2C LCD)
3. Open final_code.ino in Arduino IDE.
4. Select your board and port (Tools → Board / Port).
5. Upload.

---

How to use the calculator

• Type numbers and operators from the keypad (+ - * / and . for decimals)
• Press = to compute
• Use the rotary encoder:
  • Rotate to move the cursor left/right
  • Press the encoder button to delete at the cursor position

---

License

Educational use only. This repository is intended for learning, demonstration, and portfolio/documentation purposes.