Chip-Level Engineering: ATtiny85 Programming

The ATtiny Programming Guide teaches you how to move from "prototyping" to "production." When you finish a project (like a single blinking LED), stuffing an entire $20 Arduino Uno board inside your 3D printed case is an enormous waste of money and space. The solution is the $2 ATtiny85 chip.

ICSP Programming Protocol

The ATtiny chip does not have a USB port. You cannot plug it into your computer. Instead, you must use a dedicated hardware programmer, like the USBasp, or you can use your old Arduino Uno as the programmer (ArduinoISP).

1. The Pinout Math: You connect 6 specific pins from the USBasp to the bare ATtiny on a breadboard: MISO, MOSI, SCK (Serial Clock), RESET, VCC, and GND.
2. The IDE Setup: You add the "ATTinyCore" by SpenceKonde to your Arduino IDE Boards Manager.
3. The Burn: You select "ATtiny85" from the boards list, select "USBasp" as your Programmer, and hit "Upload."
4. The IDE compiles the code, and instead of sending it over Serial USB, it literally jams the binary data into the tiny chip's memory over the raw hardware pins!

Hardware Constraints

• ATtiny85 Chip: Just 8 pins. 5 are usable I/O, 2 are power/ground, and 1 is a reset.
• USBasp Programmer: The bridge.
• Tiny Memory Space: The chip only has 8KB of flash memory. You cannot run massive TFT screens or complex libraries on this. It is designed for simple, robust tasks: reading a button, running a timer, or turning on an LED strip.

Mastering this skill is the true mark of graduating from an "Arduino Hacker" to an "Electronics Manufacturer."