I started by sketching a quick diagram of how the whole device should work. Then I built a web page with an 800×480px canvas , the exact resolution of the display. Every hour, a server renders this page, captures it as a 1-bit bitmap, and publishes it at a fixed URL. The ESP32 simply wakes up, downloads the bitmap, paints it on the e-ink panel, and goes back to deep sleep. It never runs any of the app logic itself, that’s what makes the battery last for months.