I have sourced an e-ink writing pad from China together with its SDK, however their companion app is Chinese-only and packed with features I don’t need. I want a lean, business-friendly solution built around two work-streams that run in parallel: 1) Hardware add-on You will design and prototype a small board that physically mounts to the pad and offers three tactile buttons: “Next Page”, “Save File”, and “Upload File”. Pressing any of them must be recognised by the pad and forwarded to the mobile app exactly as if the original firmware had issued the commands. Feel free to choose Bluetooth Low Energy, USB-HID, or another lightweight link as long as the latency stays imperceptible and the pad’s battery life is not noticeably affected. 2) Android app rewrite Using the manufacturer’s SDK, the app must: • Stream pen coordinates and pressure sensitivity in real time, rendering smooth strokes on screen. • Listen for the three hardware button events and trigger the matching actions (create new page, save locally, upload to a server/folder I can later specify). • Export pages as PNG or PDF. A clean Material 3 UI, minimal permissions, and code written in Kotlin (preferred) or Java will keep maintenance easy. Deliverables • Schematics, BOM, and firmware for the add-on board • 1 working hardware prototype shipped to me for field testing • Android Studio project with full source, build instructions, and signed APK • Short demo video proving the complete workflow: write → next page → save → upload Acceptance criteria The pen trace on the phone must mirror the pad with <50 ms lag, every button press must register first time, and all data should remain intact after forty consecutive pages. If this matches your skillset in embedded electronics, BLE/USB firmware, and Android development, I’m ready to start right away and iterate quickly on meaningful milestones.