ESP32 Open-Source Wi-Fi MAC
A Wi-Fi MAC layer for the ESP32 written in C on reverse-engineered hardware registers, extending the open-source esp32-open-mac project.
Taipei / firmware, OTA, backend, device-to-cloud
Yi-Cheih (Jason) Hsu
Embedded and backend engineer for networking and IoT devices, from bootloader to cloud services.
At Airgain, I own OTA upgrades for an OpenWrt-based cellular repeater controller and built and operate its FastAPI distribution service. Previously, I built a two-stage U-Boot for Marvell switches. At Morelink, I built one Go codebase for an OpenWrt agent and a GCP service, connected through RabbitMQ with MongoDB-backed REST APIs, and led a team of five building a repeater management platform deployed to six ISPs.
Boot order of the stack I work on. Each layer links to the role behind it.
About
My university work focused on backend and IoT systems. I moved into embedded firmware in 2020.
- Bootloader to cloud: U-Boot, device trees, OpenWrt, OTA pipelines, and the services that keep devices in the field up to date.
- Backend experience: I developed a chatbot back end and designed its database architecture, and built a distributed crawler using Redis on Raspberry Pi. For ilivenet, I led an eight-person team and designed the architecture. The platform used a Flask API and Elasticsearch and reached 10,000 monthly active users within a month.
- Hard bugs on real hardware: from OTA releases that reported success without flashing to a path-MTU black hole on cellular links.
- Security background: M.S. thesis on post-quantum cryptography for vehicle forensics; co-founder and CTO of a digital forensics consultancy.
- Teaching: taught Python to 30 engineers at Senao and lectured on vehicle network security at ITRI.
Software Engineer
Airgain, Inc.
Apr 2025 - Present · Taipei, Taiwan
- Own OTA upgrades end to end for an OpenWrt-based cellular repeater controller, from device tree and U-Boot through sysupgrade, SNMP agent, web GUI, and distribution service.
- Root-caused OTA releases that reported success without flashing to a console=null bootarg. Added SHA-256 checks and a reboot-confirmed run record, and fixed a path-MTU black hole that stalled cellular downloads.
- Built and operate the OTA service in FastAPI over WireGuard with systemd crash-loop protection. Prototyped AWS IoT Core delivery with per-device X.509 certificates, IoT Jobs over HTTPS, and S3 presigned URLs.
Solution Architect (Consultant)
Morelink Technology Corporation
Jul 2023 - Mar 2026 · Taipei, Taiwan
- Architected and led a team of five building a 4G/5G repeater management platform deployed to six ISPs worldwide.
- Built one Go codebase for a MIPS OpenWrt agent and a Dockerized GCP service, linked by AMQP pub/sub on RabbitMQ, with MongoDB-backed REST APIs and Socket.IO feeding Vue.js dashboards.
- Set up GitLab CI for unit tests and cross-compiled MIPS, amd64, and aarch64 builds.
Software Firmware Engineer
Senao Networks, Inc.
Aug 2022 - May 2024 · Taipei, Taiwan
- Built a two-stage U-Boot for Marvell AC5X-class switches with I2C EEPROM identity, DRAM POST, checksum, magic, and board-name validation, USB/TFTP recovery, and factory tests.
- Integrated a Realtek RTL9313 L3 PoE+ model and the Marvell CPSS SDK into an L2/L3 switch stack. Fixed an ACL DSCP bit-shift bug in the HAL, plus IGMP/MLD snooping and loopback-recovery defects.
- Automated verification in Python with Requests and Scapy, cutting 48-port test time by 83%, from 144 to 24 minutes.
Projects
All projectsVFCS: Vehicle Forensics Cloud System
My M.S. thesis. A system that collects driving data from a car, protects it with post-quantum cryptography, and keeps a verifiable chain of custody.
ilivenet (startup, 2019)
A search platform for live streams across YouTube, Twitch and Facebook. It reached 10,000 monthly active users within its first month.