Lee K.

Embedded hardware engineer with 30 years of experience taking products from schematic to working firmware. I design the board and write the code that runs on it, so hardware and firmware fit together from day one. WHAT I DO - Schematic & circuit design: power (buck/LDO, PoE), sensor front-ends (RTD, analog), communication interfaces - PCB layout: 2 to 6+ layer boards, industrial and compact form factors, production-ready Gerber/BOM/Pick & Place - Firmware: Embedded C on STM32, ESP32 / ESP32-S3, ARM Cortex-M, FreeRTOS - Interfaces & protocols: Ethernet, CAN / J1939, RS-485 / Modbus, UART, SPI, I2C, Wi-Fi, BLE - Bring-up & debugging: board bring-up, driver development, troubleshooting existing designs RECENT WORK - ESP32-S3 Industrial Controller: Ethernet, PoE, RTD inputs, schematic through PCB layout - ESP32 Security Controller: PCB design and production release - 6-Layer Circular PCB: compact, high-density layout - Automotive CAN / J1939 firmware TOOLS Altium Designer, KiCad, STM32CubeIDE, ESP-IDF, oscilloscope and logic analyzer HOW I WORK - I work mainly through written communication (Upwork messages, documents). Clear, detailed written updates. - I share progress with schematics, layout screenshots, and test results at each milestone. - Based in South Korea (KST). Fast replies, usually within a few hours. If you need a board designed, firmware written, or both, send me your requirements. I'll reply with a clear plan and estimate.