What is Hub Mode?

Modern Android puts apps to sleep aggressively. Doze mode, app standby, manufacturer-specific battery saving (Xiaomi, OPPO, Samsung, Huawei) — they all kill background work the moment your phone goes idle. For a grow automation app polling sensors every 5 minutes and pushing fan/light commands, that is a problem.

Hub Mode is GrowVPD Pro’s answer. Designate any Android phone (your daily driver, an old phone in a drawer, anything running Android 9+) as the “hub”. The app then runs an always-on foreground service that:

  • Polls every connected smart device every 5–15 min, regardless of screen state
  • Re-evaluates automation rules on a fixed cadence
  • Streams sensor data to your diary in real-time
  • Auto-restarts on boot
  • Stays whitelisted from battery optimisation

One persistent notification, very low battery (~3–5% / day for a phone plugged in), and your grow keeps running even if the rest of your phone is asleep.

When You Need Hub Mode

Hub Mode is recommended any time your automation matters more than your phone’s battery life:

  • You leave the house for the day and want VPD-based fan adjustments to keep happening.
  • You run BLE sensors that need a phone within range (SANlight, Spider Farmer some models).
  • You use Tuya battery TH sensors via Cloud Bridge — the Pulsar push needs an active subscriber.
  • You want camera snapshots taken at scheduled intervals while you sleep.
Field-tested setup. Many of our beta users dedicate an old Pixel 3 or Galaxy S9 (~$80 used) plugged in next to the tent. Hub mode + grid power = zero failures.

Enabling Hub Mode

Step 1

Open Settings

Settings → Hub Mode. You see two states: “This is the hub” (off by default) and “Connect to a hub” (off by default).

Step 2

Mark this phone as the hub

Toggle “This is the hub”. The app will:

  1. Request the foreground service notification permission (Android 13+).
  2. Open your phone’s battery optimisation settings and ask you to whitelist GrowVPD Pro.
  3. Register a boot receiver so hub mode auto-starts after restarts.

Approve all three. The persistent notification appears immediately.

Step 3

(Optional) Pair other phones

Open GrowVPD Pro on your daily phone. Settings → Multi-Device Sync → Connect to hub. The hub generates a QR code; scan it. Both devices now share the diary, paired over LAN with end-to-end encryption (libsodium box). See the multi-device sync guide for details.

Manufacturer-Specific Battery Settings

Stock Android handles whitelisting cleanly. Customised skins need extra steps:

  • Xiaomi MIUI / Redmi — Settings → Apps → GrowVPD Pro → Battery saver → No restrictions. Then Settings → Battery & performance → App battery saver → GrowVPD → No restrictions. Also enable Autostart.
  • OPPO ColorOS / Realme / OnePlus — Settings → Battery → Sleep standby optimisation → OFF for GrowVPD. Add to Locked apps in recent task drawer.
  • Huawei EMUI — Settings → Battery → App launch → GrowVPD → Manage manually → enable all toggles.
  • Samsung One UI — Settings → Apps → GrowVPD → Battery → Unrestricted. Settings → Device care → Battery → Background usage limits → Never sleeping apps → add GrowVPD.

The hub-mode wizard tries to deep-link these screens automatically. If a brand changes the menu structure between versions, drop us a screenshot on Discord and we’ll patch the deep-link.

Power Use

On a Pixel 6 plugged in 24/7:

  • Idle hub (no automation rules firing): ~2% battery / hr screen-off, but charging keeps it pinned at 100%.
  • Active hub (rules firing every 5 min, 6 devices): ~3–5% / hr screen-off.

Plug it in. If you must run on battery (fieldwork, off-grid), expect 12–18 h before recharge.

Cloud Relay Fallback (Pro)

If your hub goes offline (router reboot, power outage, airplane mode by mistake), GrowVPD Pro can fall back to our cloud relay:

  • The hub maintains a persistent outbound cloud connections to relay.growvpd.pro.
  • Other paired devices reconnect to the relay if they lose direct LAN visibility to the hub.
  • The relay only forwards encrypted Noise framed messages — we cannot read your sensor data or commands.

Relay is opt-in, off by default for fully local-first users. Enable in Settings → Hub Mode → Use cloud relay if hub unreachable.

Troubleshooting

“Hub keeps stopping” — nine times out of ten this is manufacturer battery saving. Walk through the brand-specific steps above carefully. The MIUI “Autostart” step is the most commonly missed.

“Notification disappeared” — restart the app once. Android sometimes garbage-collects foreground service notifications after OS updates.

“Other phone can’t see the hub” — both devices must be on the same Wi-Fi network and mDNS discovery must work. Some routers block mDNS by default (TP-Link Deco, Asus AiMesh) — enable it in router settings, or fall back to QR pairing which works regardless.