Five Hours, Five Root Causes, Crisis Averted: A Case Study in Agentic Embedded Debugging
A colleague had just reached a critical milestone, getting a stable LVGL-based UI running on our product’s 5" MIPI display. It was a significant piece of driver work: MicroPython application code on an NXP i.MX RT1176 (Cortex-M7 @ 1 GHz), driving LVGL v9 on a 720x1280 MIPI DSI touchscreen. An embedded system, not a phone or PC. The UI worked, but the on-screen keyboard was unusable. Each keypress took nearly 200ms to render, dropping to 1-2 FPS while typing, missing many keypresses entirely. For context, touchscreen input generally needs 30+ FPS (under 33ms per frame) to feel responsive, and 60+ FPS to feel smooth. We were at 5 FPS on a good frame. That performance is unusable for a client demo, let alone a shipping product, and without any obvious cause for the lag it wasn’t clear if we had a fundamental hardware/design failure or a fixable configuration issue. ...