https://www.youngju.dev/blog 천천히 올바르게. AI Researcher & DevOps Engineer Youngju's tech blog. GPU/CUDA, LLM, MLOps, Kubernetes AI workloads, distributed training, and data engineering. ko fjvbn2003@gmail.com (Youngju Kim) fjvbn2003@gmail.com (Youngju Kim) Wed, 17 Jun 2026 00:00:00 GMT https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-ble-wireless-communication.en https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-ble-wireless-communication.en We design the BLE wireless communication at the heart of the FingerScore smart-scoring ring from the ground up. GAP/GATT concepts, a custom score service, pairing security, Web Bluetooth and Android integration, power saving, and debugging — all explained so a beginner can follow along. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscoreblebluetoothgattembeddediotwireless https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-ble-wireless-communication.ja https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-ble-wireless-communication.ja FingerScore スマートスコアリングリングの核心である BLE 無線通信をゼロから設計します。GAP/GATT の概念、カスタムスコアサービス、ペアリングのセキュリティ、Web Bluetooth と Android 連携、省電力とデバッグまで、初心者でも追えるように整理します。 Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscoreblebluetoothgattembeddediotwireless https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-ble-wireless-communication https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-ble-wireless-communication FingerScore 스마트 점수기록 링의 핵심인 BLE 무선 통신을 처음부터 설계합니다. GAP/GATT 개념, 커스텀 점수 서비스, 페어링 보안, Web Bluetooth와 Android 연동, 전력 절약과 디버깅까지 입문자도 따라올 수 있게 정리합니다. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscoreblebluetoothgattembeddediotwireless https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-electronics-fundamentals.en https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-electronics-fundamentals.en Everything you need from electronics fundamentals to build the FingerScore ring device, in one piece. We walk through Ohm law and voltage dividers, pull-up and pull-down resistors, capacitors, LED current-limiting calculations, GPIO and logic levels, I2C/SPI/UART, ADC, and measurement with a multimeter and oscilloscope, in a way a beginner can follow. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscoreelectronicshardwaregpioi2cembedded https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-electronics-fundamentals.ja https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-electronics-fundamentals.ja FingerScore のリングデバイスを自作するために必要な電子工学の基礎を一本にまとめます。オームの法則と分圧、プルアップ／プルダウン抵抗、コンデンサ、LED の電流制限計算、GPIO とロジックレベル、I2C/SPI/UART、ADC、テスターとオシロスコープでの測定まで、初心者でも追えるように解説します。 Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscoreelectronicshardwaregpioi2cembedded https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-electronics-fundamentals https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-electronics-fundamentals FingerScore 링 디바이스를 직접 만들기 위한 전자공학 기초를 한 편에 정리합니다. 옴의 법칙과 전압 분배, 풀업/풀다운 저항, 커패시터, LED 전류 제한 계산, GPIO와 로직 레벨, I2C/SPI/UART, ADC, 멀티미터와 오실로스코프 측정까지 초보자도 따라올 수 있게 설명합니다. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscoreelectronicshardwaregpioi2cembedded https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-hardware-system-overview.en https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-hardware-system-overview.en This is part one of a hardware series on building the FingerScore ring-shaped score recorder yourself. It walks through translating product requirements into circuits, the system block diagram from sensor to MCU to radio to power, a comparison of MCU+BLE SoCs, input methods, and power sources, plus a real BOM example and the learning tools and budget, all in a way a beginner can follow. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorehardwareelectronicsbleembeddedpcb https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-hardware-system-overview.ja https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-hardware-system-overview.ja FingerScore のリング型スコア記録器を自分で作るハードウェアシリーズの第1回です。製品要件を回路へ翻訳する方法、センサーから MCU、無線、電源へとつながるシステムブロック図、MCU+BLE SoC と入力方式と電源の比較、そして実際の BOM 例や学習に必要な道具と予算まで、初心者でも追えるようにまとめます。 Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorehardwareelectronicsbleembeddedpcb https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-hardware-system-overview https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-hardware-system-overview FingerScore 반지형 스코어 기록기를 직접 만드는 하드웨어 시리즈의 1편입니다. 제품 요구사항을 회로로 번역하는 법, 센서·MCU·무선·전원으로 이어지는 시스템 블록 다이어그램, MCU+BLE SoC와 입력 방식과 전원의 비교, 그리고 실제 BOM 예시와 학습 도구·예산까지 초보자도 따라올 수 있게 정리합니다. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorehardwareelectronicsbleembeddedpcb https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-mcu-firmware-gesture-input.en https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-mcu-firmware-gesture-input.en This post covers the brain of the FingerScore BLE ring device for racket-sports score keeping: the MCU firmware. From the structure of init, main loop, interrupts, and low-power sleep, through detecting buttons and gestures with GPIO interrupts, debouncing, an IMU threshold state machine, and the flow from event to score increment, all illustrated with compilable C code examples. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorefirmwaremcuembeddedgesturelow-power https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-mcu-firmware-gesture-input.ja https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-mcu-firmware-gesture-input.ja ラケットスポーツのスコア記録用 BLE リングデバイス FingerScore の頭脳である MCU ファームウェアを扱います。初期化・メインループ・割り込み・低電力スリープの構造から、GPIO 割り込みによるボタンとジェスチャーの検出、デバウンス、IMU のしきい値ステートマシン、イベントからスコア加算までの流れを、コンパイル可能な C コード例とともに整理します。 Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorefirmwaremcuembeddedgesturelow-power https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-mcu-firmware-gesture-input https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-mcu-firmware-gesture-input 라켓 스포츠 점수 기록용 BLE 링 디바이스의 두뇌, MCU 펌웨어를 다룹니다. 초기화·메인 루프·인터럽트·저전력 슬립의 구조부터 GPIO 인터럽트로 버튼과 제스처를 감지하는 법, 디바운싱, IMU 임계값 상태 머신, 이벤트에서 점수 증가까지의 흐름을 컴파일 가능한 C 코드 예제와 함께 정리합니다. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorefirmwaremcuembeddedgesturelow-power https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-pcb-design-miniaturization.en https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-pcb-design-miniaturization.en We cover the final step that turns the FingerScore circuit into a real, touchable ring: PCB design. The schematic-to-PCB flow, component placement and routing, ring form-factor constraints, 2.4GHz antenna layout, DFM and Gerber output, assembly, and even mass production and certification — all in a beginner-friendly way. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorepcbkicadantennaminiaturizationhardwaremanufacturing https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-pcb-design-miniaturization.ja https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-pcb-design-miniaturization.ja FingerScore 回路を本当に触れる指輪にする最後の段階、PCB 設計を扱います。スキマティックから PCB への流れ、部品配置とルーティング、指輪フォームファクターの制約、2.4GHz アンテナレイアウト、DFM とガーバー出力、アセンブリ、そして量産と認証まで初心者にやさしく整理します。 Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorepcbkicadantennaminiaturizationhardwaremanufacturing https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-pcb-design-miniaturization https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-pcb-design-miniaturization FingerScore 회로를 실제로 만질 수 있는 반지로 만드는 마지막 단계, PCB 설계를 다룹니다. 스키매틱에서 PCB로 가는 흐름, 부품 배치와 라우팅, 반지 폼팩터 제약, 2.4GHz 안테나 레이아웃, DFM과 거버 출력, 어셈블리, 그리고 양산과 인증까지 입문자 친화적으로 정리합니다. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorepcbkicadantennaminiaturizationhardwaremanufacturing https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-power-battery-circuit-design.en https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-power-battery-circuit-design.en We cover, from scratch, the power design that actually keeps the FingerScore ring on. A power budget calculation, coin cell vs. LiPo, charging ICs and protection circuits, LDOs and buck converters, decoupling, low-power techniques, and heat, ESD, and safety — all in a beginner-friendly way. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorepowerbatterylipocircuitembeddedhardware https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-power-battery-circuit-design.ja https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-power-battery-circuit-design.ja FingerScore リングを本当に点け続けるための電源設計をゼロから扱います。電力予算の計算、コインセル対 LiPo、充電 IC と保護回路、LDO とバックコンバータ、デカップリング、低電力技法、そして発熱・ESD・安全まで初心者にやさしく整理します。 Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorepowerbatterylipocircuitembeddedhardware https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-power-battery-circuit-design https://www.youngju.dev/blog/architecture/2026-06-17-fingerscore-power-battery-circuit-design FingerScore 링을 진짜로 켜 두기 위한 전원 설계를 처음부터 다룹니다. 전력 예산 계산, 코인셀 대 LiPo 선택, 충전 IC와 보호회로, LDO와 벅 컨버터, 디커플링, 저전력 기법, 그리고 발열·ESD·안전까지 입문자 친화적으로 정리합니다. Wed, 17 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) fingerscorepowerbatterylipocircuitembeddedhardware