2025 COSS MCU Contest

Archive of our work for the 2025 COSS Next Semiconductor MCU Application Contest
Built by Hong Baksa and Kids across Day 1 and Day 2 challenges.

Quick Links
Day 1 Demo A · Day 1 Demo B · Day 2 AVR Demo · Day 2 STM32 Demo

This repository collects four MCU projects built with ATtiny85, AVR, and STM32. It is organized as a compact contest portfolio, with source code, reports, circuit diagrams, and demo videos kept together so each result can be reviewed in one place.

At a Glance

Day	Project	Platform	Focus	Quick Links
Day 1 A	Stopwatch / Bomb Timer	ATtiny85 + TM1650	7-segment display, button input, buzzer, LED, timer interrupts	Code / Report / Demo
Day 1 B	Hotel Safe	ATtiny85 + TM1650	Password input, lock state machine, audio feedback, success/error interaction	Code / Report / Demo
Day 2 AVR	HUB75 LED Tetris	AVR + Dual HUB75 64x32	Virtual 64x64 rendering, game logic, scoring effects, PWM scan loop	Code / Report / Demo
Day 2 STM32	LED MATRIX - Night of Gwangalli	STM32 + HUB75 Panel	Fireworks animation, background composition, traffic overlay, PWM sound	Code / Report / Demo

Highlights

Day 1 - ATtiny85 Projects

1) Stopwatch / Bomb Timer

This project uses an ATtiny85 and a TM1650 4-digit 7-segment module to build a dual-mode timer. It switches between a standard stopwatch mode and a bomb timer mode, while handling 0.1-second timing, button-based state transitions, buzzer warnings, and LED feedback.

• Key points

  • Timer0-based 1 ms system timer
  • Timer1 PWM buzzer output
  • Software I2C control for the TM1650
  • Dedicated countdown and melody logic for bomb mode

• Links

  • Source Code
  • Report
  • Circuit Diagram
  • Demo Video

2) Hotel Safe

This project turns an ATtiny85 and TM1650 keypad/display setup into a 4-digit password safe. It focuses on password checking, setting mode, repeated failure tracking, a 10-second lock state, and responsive audio and display feedback for success and error cases.

• Key points

  • Password input and edit state management
  • Lock countdown after four failed attempts
  • Interrupt-driven asynchronous sound system
  • Segment animation for success and failure feedback

• Links

  • Source Code
  • Report
  • Circuit Diagram
  • Demo Video

Day 2 - Display Projects

3) HUB75 LED Tetris (AVR)

This AVR project chains two 64x32 HUB75 panels vertically to create a virtual 64x64 display and runs a 2x-scale Tetris implementation on top of it. It includes input auto-repeat, automatic drop, collision and line-clear handling, score effects, and GAME/END plus STAGE CLEAR rendering states.

• Key points

  • HUB75 row-pair scan with 2-bit PWM
  • Virtual 64x64 coordinate-based rendering
  • Score-driven speed changes and stage effects
  • Lightweight game logic tuned for AVR constraints

• Links

  • Source Code
  • Report
  • Circuit Diagram PNG
  • Demo Video

4) LED MATRIX - Night of Gwangalli (STM32)

This visual project combines fireworks, a bridge background, moving traffic, and sound on a 128x32 LED matrix. It is structured around TIM2 interrupt-driven panel scanning, framebuffer rendering, fireworks simulation, and TIM3 PWM-based audio output split across several modules.

• Key points

  • panel.c: HUB75 panel scanning and bit-plane PWM
  • fireworks.c: launch, explosion, and special-text animation logic
  • bridge.c / traffic.c: background image and moving traffic overlay
  • sound.c: rising and explosion sound effects

• Links

  • Main Code
  • Report
  • Circuit Diagram PNG
  • Demo Video

Repository Structure

2025-COSS-MCU-Contest/
|- README.md
|- poster.png
|- 홍박사와 아이들 1일차 과제/
|  |- 과제 A/
|  |  |- main.c
|  |  |- 홍박사와 아이들 과제 A 보고서.pdf
|  |  |- 홍박사와 아이들 과제 A 회로도.pdf
|  |  `- 홍박사와 아이들 과제 A 시연 영상.mp4
|  `- 과제 B/
|     |- main.c
|     |- 홍박사와 아이들 과제 B 보고서.pdf
|     |- 홍박사와 아이들 과제 B 회로도.pdf
|     `- 홍박사와 아이들과제 B 시연 영상.mp4
`- 홍박사와 아이들 2일차 과제/
   |- AVR/
   |  |- main.c
   |  |- 홍박사와 아이들 2일차 AVR 보고서.pdf
   |  |- 홍박사와 아이들 2일차 과제 AVR 회로도.png
   |  `- 홍박사와아이들 1일차 시연영상_AVR.mp4
   `- STM/
      |- 소스파일/
      |- 헤더파일/
      |- 홍박사와 아이들 2일차 STM32 보고서.pdf
      |- 홍박사와 아이들 2일차 과제 STM32 회로도.png
      `- 2일차 시연영상_STM32.mp4

Tech Notes

• The Day 1 projects focus on input, display control, sound, and state handling around ATtiny85 and TM1650.
• The Day 2 AVR project explores game logic and LED panel driving under tight resource constraints.
• The Day 2 STM32 project is more modular, with timer-driven panel refresh, animation, overlay, and sound separated into dedicated files.

Team

This project was developed by a five-member team.

Role	Name
Team Leader	Park Gyuhyeon
Member	Hong Soonhyun
Member	Song Seonghyeok
Member	Lim Songju