Introduction: 🔧 Want to REALLY Understand How a Microcontroller Works? Start With Registers!
All computers and microcontrollers – old or new – are based on one thing: registers.
In the end, programming is nothing more than this: writing a 1 or a 0 into a register.
Supplies
arduino nano
usb cable
pc with browser chrome
open https://costycnc.github.io/avr-compiler-js/
Step 1: All Computers and Microcontrollers – Old or New
Are based on one thing: registers. In the end, programming is nothing more than this: writing a 1 or a 0 into a register.
Step 2: 🧠 Imagine a Cabinet Full of Drawers
Each drawer has compartments. In an ATmega328 (like on an Arduino Uno), each drawer has 8 "slots". In modern PCs, it’s 32 or 64.
Example: Drawer 5, slot 5 is linked to digital pin 13, the onboard LED.
Write a 1 there? The LED turns on.
Write a 0? The LED turns off.
Step 3: ⚡ Try It Yourself in 30 Seconds!
- Open 👉 https://costycnc.github.io/avr-compiler-js/
- Plug in your Arduino via USB
- Upload this code:
- LED turns on! Now try:
Boom – the LED is off. You just spoke directly to the silicon.
Step 4: 📘 What About Drawer 5? It’s Real!
Check the ATmega328 datasheet — drawer 5 is there. Every drawer controls something: ports, timers, interrupts, peripherals…
Step 5: 🔍 Curious What the Other Drawers Do?
Let’s find out together. No libraries. No abstraction. Just bits and registers.
Step 6: Video Demonstration
https://www.youtube.com/watch?v=uGtZ6oYpXiM
https://www.youtube.com/shorts/0BqAmP68bWY
