Tomasz Burzy wanted his blood pressure readings over WiFi without a cloud account or subscription. He reverse-engineered a basic consumer monitor and landed on an ESP32-CAM reading the LCD optically, with the final project published on GitHub.
The hardware path failed in a specific and instructive way. A logic analyzer found a raw pressure sensor test point, but the final display value is derived from proprietary firmware, not raw sensor data. The main processing chip and display driver turned out to be a single integrated IC, making signal interception impossible without decapping the chip.
The optical solution works because Burzy maps exact pixel coordinates for each LCD segment and checks only those coordinates for brightness, no computer vision library required. That constraint-driven insight is why the full write-up is worth reading: the dead ends reveal more about locked-down consumer hardware than the solution does.
[READ ORIGINAL →]