COSCUP 2026 開源人年會

Consumer IoT devices, such as digital photo frames, often rely on heavy operating systems (like Android) and touchscreens just to handle basic setups like Wi-Fi and API configurations. This approach not only complicates the hardware design but also limits the device's lifespan—once OS updates stop, the device often becomes obsolete or a security risk.

"Tac Photo" is an open-source digital photo frame project that takes a different approach. By using an ESP32-S3 running FreeRTOS instead of a heavy OS, the device remains lightweight and functional over the long term without requiring frequent software updates.

To configure the device without a screen, we separated the setup process from the hardware itself. Users configure their settings (Wi-Fi credentials, cloud sync) on a smartphone app, which encrypts and writes this data to a standard passive NFC card. Tapping this physical card to the frame updates its state instantly.

In this session, I will share the architecture and practical lessons learned from building this system. Participants will explore:

1. Hardware-Software Integration: Using standard NFC to shift complex UI tasks to a smartphone, leaving the hardware simple, single-purposed, and easy to maintain.

2. Headless Cloud Connections: How to securely transfer encrypted OAuth refresh tokens via NFC to connect to cloud services (like Google Photos) without a device-side browser.

3. Longevity & Right to Repair: How choosing an RTOS over a full OS, combined with a minimalist, open hardware design, aligns with the Right to Repair movement, empowering users to customize and fix their own digital appliances.

This talk provides a practical framework for developers looking to build simple, repairable, and long-lasting IoT devices using FOSS tools.