Dat H.

I take embedded products from schematic to mass production: circuit design, PCB layout, firmware and the companion app, done by one person. 3+ years, 10+ real projects, and consumer products already in end users' hands. Hardware design (KiCad, EasyEDA) • Multilayer PCBs up to 8 layers, HDI with laser microvias and via-in-pad, tiny wearable boards under 12 mm wide • Controlled impedance: 90 Ω USB pairs, 50 Ω RF lines, length matching • RF: BLE/Wi-Fi antenna placement and keep-outs, 13.56 MHz NFC antenna design and matching • Power: Li-ion charging, solar input, buck/boost, eFuse and inrush protection, µA-level sleep budgets • EMC-aware layout: solid planes, return paths, via stitching, ready for FCC/CE pre-scan • Schematic and part selection checked pin by pin against datasheets, design review before every fab • Production output: Gerber, drill, BOM, pick-and-place for JLCPCB/PCBWay turnkey assembly, DFM/DFT test points, 3D STEP, enclosure CAD in FreeCAD Firmware • STM32 (F0/F1/F4/L0/L4), ESP32/S3/P4/C3, nRF52832/nRF52840, RP2350, ARM Cortex-M, RISC-V • FreeRTOS (queues, semaphores, event groups, task notifications), bare metal, custom bootloaders, OTA • I2C, SPI, I2S, PDM, UART, PWM, ADC/DAC, RMT, USB HID/CDC, Modbus RTU • Wi-Fi, BLE, ESP-NOW, LoRa, NFC, GSM/GPRS, NB-IoT, 4G; MQTT, HTTP(S), WebSocket, TCP/UDP; Azure IoT, AWS, Firebase • IMU, ToF, fingerprint, ambient light, temperature/humidity, gas, water quality, heart rate/SpO2, camera, mic, speaker, TFT/OLED/LCD/HMI • C/C++ first, plus Python and Java • ESP-IDF, CMake, Makefiles, linker scripts, GCC, GDB/JTAG, no IDE needed • Embedded Linux (Raspberry Pi, Orange Pi), edge AI on MCUs, VoIP, WireGuard, MCP integration with backend teams Companion apps for your device • Flutter/Dart mobile and desktop apps built together with the firmware, so the BLE, USB and NFC protocol is designed once for both sides • Device setup and Wi-Fi provisioning, live data, settings, firmware updates over BLE or USB from the app • Python tools for bring-up, factory test and flashing Security • FIDO2/U2F security keys over USB and NFC, Secure Boot, encrypted NVS, flash read-out protection • Secure elements (NXP SE050), hardware signing devices, ISO 18013-5 mobile driver's license (mDL) SDK • Firmware reverse engineering and EEPROM analysis of existing products Because I design the board and write the firmware, pin choices, power states and test points are planned together. The first boards come up faster, and going from 10 units to 10,000 brings fewer surprises. If you're a startup that needs one person to take a hardware product from prototype to production, let's talk.