Six self-contained microcontroller projects on the ATmega2560: a custom Arduino-Mega-class PCB designed in Eagle and exported as production-ready Gerbers, a bare-metal 40 kHz ADC sampler, a hand-rolled IR link-layer protocol, an interrupt-driven music game, a tone-table melody player, and a sensor-validation suite for a self-balancing robot.
This repository is a curated showcase of six embedded-systems projects targeting the Arduino Mega 2560 (Microchip ATmega2560 @ 16 MHz), covering the design surface from custom-PCB hardware design through bare-metal register-level firmware up to multi-sensor robotics integration.
The projects span four categories:
| Category | Projects |
|---|---|
| Hardware design | custom-mega-pcb/ |
| Bare-metal firmware | bare-metal-adc-sampler/, interrupt-music-box/ |
| Protocol design | ir-link-layer-protocol/ |
| Robotics integration | self-balancing-validation/, tone-melody-player/ |
What you can read off this repository. Every project here is small enough to read in ten minutes and demonstrates a specific embedded-systems skill: PCB schematic capture and Gerber export (custom-mega-pcb), direct AVR register access without the Arduino abstraction layer (bare-metal-adc-sampler), multi-vector interrupt coordination (interrupt-music-box), link-layer protocol design (ir-link-layer-protocol), and smoke-test-driven sensor bring-up (self-balancing-validation).
A 4-layer Eagle CAD design of an Arduino-Mega-2560-class board: ATmega2560 @ 16 MHz, USB-Serial via ATmega16U2, full pin breakout, LDO power section, and Mega-shield-compatible header layout. Ships schematic, board file, full Gerber output, drill files, and pick-and- place files for both sides — i.e. everything a fab needs to manufacture the board.
A direct-register-access ATmega2560 ADC sampler with deterministic 25 µs sample period, a Timer1 CTC interrupt as the only conversion trigger, a 256-entry ring buffer, and inline threshold-based event detection. Demonstrates ISR-safe lock-free producer/consumer patterns and bare-metal AVR programming.
A bidirectional link-layer protocol over a 38 kHz IR carrier between two ATmega2560 boards: source/destination addressing, broadcast, runtime baud-rate selection, framed packets with XOR checksum validation, and an input-capture-driven receive state machine. Not NEC / RC-5 — a custom protocol designed for point-to-point data transfer rather than remote-control button presses.
Starts with a 3-note speaker driven by a Timer3 output-compare ISR
(no tone(), no delay()), escalates to a Simon-says music game
with debounced button input and a scoring state machine, finishes
with a refined version that adds a runtime-configurable input window.
Demonstrates concurrent ISR coordination across three vector
groups.
A simple gateway project: hold a button → play We're Off to See the
Wizard. Uses a hand-rolled half-period table for exact pitches
rather than the Arduino tone() quantiser. Ships a 12-second demo
clip.
Three short Arduino sketches that bring up the individual peripherals of a self-balancing robot — MPU-6050 IMU, TB6612FNG H-bridge driver, and the regulator's power rails — before the closed-loop controller is ever turned on. Validation sketches prevent the "three-sensors-and-two-motors-all-fail-at-once" debugging trap.
arduino-mega-microcontrollers/
├── README.md # this file
├── LICENSE
│
├── custom-mega-pcb/ # 1. Skyboard — custom PCB design
│ ├── schematic/ # .sch + .brd
│ ├── gerbers/ # production-ready outputs
│ └── docs/ # layout PNGs + ERC report
│
├── bare-metal-adc-sampler/ # 2. 40 kHz ADC sampler
│ └── src/adc_sampler/
│
├── ir-link-layer-protocol/ # 3. IR link-layer protocol
│ └── src/ir_link/
│
├── interrupt-music-box/ # 4. Timer-driven music sketches
│ ├── src/music_box/
│ ├── src/music_game/
│ ├── src/music_game_advanced/
│ └── docs/ # speaker-output demo
│
├── tone-melody-player/ # 5. Button-triggered melody
│ ├── src/melody_player/
│ └── docs/ # 12-second demo clip
│
└── self-balancing-validation/ # 6. Robot peripheral smoke tests
├── mpu6050-gyro-test/
├── ultrasonic-motor-driver/
└── voltage-regulator/
- Install Arduino IDE 2.x (or
arduino-cliif you prefer the command line). - In Boards Manager, install the Arduino Mega 2560 board package.
- Open the project's
src/<project>/<project>.inoin the IDE. - Select Tools → Board → Arduino Mega or Mega 2560.
- Plug in the Mega over USB, select the right serial port under Tools → Port, and click Upload.
The PCB project (custom-mega-pcb/) is read-only as far as Arduino
is concerned — it ships the Eagle source files and the Gerber output.
To open the design, use Eagle CAD 9.x (legacy free version) or
import into KiCad via the built-in Eagle importer.
Software in this repository is released under the MIT License.