Before building a real app, I validated everything with nRF Connect first. Scan, connect, discover services, send commands, verify response. This caught firmware bugs before I ever touched Flutter - saved hours of debugging the wrong layer.

Once the device protocol was solid, I moved to Flutter. The BLE part was actually easy. The fight was Android itself: permission handling across OS versions, background scan behavior, and write/notification timing quirks. Classic mobile pain.

My approach: get scan + connect + one confirmed write working reliably before building anything else. Once that foundation was solid, the rest was normal app development - state management, UI, logging, graphs.

This was also my first Flutter app. Figured I'd learn on something real instead of another tutorial project.

What the app does:

• Connect & manage multiple filters (up to 6 units) — quick select, reconnect, and keep each one's identity straight
• Live dashboard control — fan PWM / auto mode, basic settings, and "is it actually running right now" status
• Real-time sensor streaming — inlet/outlet VOC, temp/humidity, with smooth updates
• Built-in graphing / trending — time-series plots for sensor data and filter performance so you can see what's happening, not guess
• Tap-to-inspect graph data — click a point to pull exact values + timestamp (nice for debugging and "what happened here?" moments)
• Export / share logs — CSV output for deeper analysis, backups, or sending to someone without screenshots

Nothing fancy, but it works because I didn't skip the nRF validation step.