TankSync

TankSync™ — reliable smart water monitoring

Never worry about your water tank again. A solar-powered sensor on the rooftop, a quiet hub on the wall, and smart water monitoring that keeps working — even when the internet doesn’t. Long-range LoRa (RYLR998) to an ESP32 hub, local web UI, Home Assistant via HACS, optional cloud PWA. Open at the core.

_{The indoor hub (left), the solar tank sensor with non-contact ultrasonic measurement (centre), and the custom circular TX PCB (right) — current production hardware, REV 2.2 (May 2026), tested through Delhi summer at 45°C ambient.}

Watch the story — Episode 1

_{Why I built TankSync, the local-first philosophy, and how the rooftop sensor + indoor hub stay reliable when the internet doesn't. Watch on YouTube →}

Try the in-browser flasher first

👉 tanksync.smartghar.org/firmware/

No esptool, no Python, no CLI. Plug your board into USB, click Install, the browser does the flashing through WebSerial. Works on Chrome/Edge desktop. Takes ~45 seconds per board.

Why TankSync — engineered to be reliable, not just smart

Most “smart tank” products treat the cloud as the product. TankSync treats reliability as the product — and the cloud as an optional layer of polish on top.

• Works fully offline. Hub keeps showing levels, lighting the LED ring, and beeping on overflow — even when your WiFi, your ISP, or our cloud is down. Local operation is the default; cloud is opt-in.
• Long-range LoRa, no rooftop WiFi. Sensor talks to the hub over 865 MHz LoRa — through concrete walls, between floors, across a property. Up to 5 km line-of-sight. The rooftop doesn’t need WiFi. Ever.
• Solar-powered transmitter. Mounts on the tank lid. Charges in regular daylight, runs on a single 18650, deep-sleeps between readings. Months of autonomy. No wires to the tank.
• Home Assistant native. Auto-discovery via MQTT plus a dedicated HACS integration — every tank shows up as an HA device with live sensors, fill events, and editable settings.
• Open at the core. Firmware (AGPL-3.0), hardware (CC BY-SA 4.0), schematics, BOM, and flashing tools are all public. Self-host it. Fork it. Modify it. Audit it. No vendor lock-in.
• Built for Indian realities. Designed and tested through Delhi summer (45 °C ambient). UV-stabilised PETG, IP65 sealing, monsoon-ready. Engineered for terrace tanks, high-rise apartments, thick walls, and unreliable connectivity.

Get the hardware

Skip the build — Developer Edition kits are on pre-order. Hub + solar sensor + all the bits. First batch ships end of July / early August 2026. → shop.smartghar.org Indian buyers: bank transfer accepted today. PayPal for international buyers going live this week. Or build it yourself — full BOM, schematics, and firmware are below. A free tier on the cloud is available either way.

Architecture

                    LoRa 865/915 MHz (up to 5 km, through walls)
                    ==============================================>
  TRANSMITTER                                          HUB (RECEIVER)
  ESP32-C3 SuperMini/Pro Mini                          ESP32-S3
  + JSN-SR04T Ultrasonic                               + RYLR998 LoRa
  + RYLR998 LoRa                                       + GC9A01 round TFT
  + 18650 + solar                                      + WS2812 LED ring
                                                       + WiFi (optional)
                                                          |
                                              +-----------+-----------+
                                              |                       |
                                       MQTT (TLS)              Local web UI
                                              |              192.168.x.x
                                    +---------+---------+
                                    |                   |
                              Home Assistant      Cloud dashboard
                              (HACS integration)  (optional, hosted)

Hardware

Component	Part	Approx cost (INR)
Receiver MCU (hub)	ESP32-S3 module	₹450–700
Transmitter MCU	ESP32-C3 SuperMini / Pro Mini	₹200
LoRa module	REYAX RYLR998 (×2)	₹650 each
Ultrasonic sensor	JSN-SR04T (waterproof)	₹350
Display (hub)	GC9A01 1.28" round TFT	₹300
Battery	Protected 18650 + holder	₹200
Solar charger	CN3791 MPPT module	₹120
Boost converter	MT3608 3.7 V → 5 V	₹50

Total: ~₹3,800-5,200 per complete system (one hub + one tank). Per-tank addition: ~₹1,500.

📐 Detailed wiring + pin maps → 📋 Full BOM →

Quick start

Option 1: Browser flasher (easiest — no install)

👉 tanksync.smartghar.org/firmware/

Plug your board into a USB port, pick the right card (Receiver Hub or Transmitter), click Install. Done in ~45 sec.

Option 2: esptool (CLI)

Download the latest .bin from Releases.

# Receiver / Hub (ESP32-S3) — full image, flash at 0x0
esptool --chip esp32s3 -b 460800 write_flash 0x0 tanksync-receiver-esp32s3-cam-vX.Y.Z-full.bin

# Transmitter (ESP32-C3 SuperMini / Pro Mini) — full image, flash at 0x0
esptool --chip esp32c3 -b 460800 write_flash 0x0 tanksync-transmitter-lora-esp32c3-vX.Y.Z-full.bin

# (Legacy ESP32 DevKit hubs: use tanksync-receiver-esp32-vX.Y.Z-full.bin with --chip esp32.)

Option 3: Build from source

Note on source versions. The firmware source in this repo corresponds to the rx-v2.8.6 / tx-v2.0.15 line (and earlier) and is licensed AGPL-3.0 — build it, audit it, fork it. Releases after that version are published as ready-to-flash binaries (see Releases) rather than source. The full local-first feature set and the in-browser flasher work with both.

Prerequisites: ESP-IDF v5.5+

# Receiver Hub
cd firmware/Receiver-ESP32-DevKit
idf.py build
idf.py -p /dev/ttyUSB0 flash

# Transmitter
cd firmware/Transmitter-IDF
idf.py set-target esp32c3
idf.py build
idf.py -p /dev/ttyACM0 flash

First boot

1. Hub starts in AP mode → connect to TankSync-XXXX WiFi from your phone
2. Captive portal opens (or visit 192.168.4.1)
3. Configure home WiFi + (optional) MQTT broker + LoRa settings

What you’ll use it through

Two surfaces — pick either, or both. They show the same data.

_{Left: the PWA at tanksync.smartghar.org — works from anywhere. Right: the hub's local web UI — works fully offline. Full walkthrough in the Wiki.}

4. Transmitter pairs over the air — hold its BOOT button ~3 sec (hub LED turns green when paired). Holding BOOT for >5 sec after a reset puts the transmitter into Wi-Fi AP mode for local firmware updates + diagnostics.

Photos of a real build

_{Renders of the production sensor — the threaded boss + hex lock-nut secure the sensor through a standard tank-lid hole; the solar panel sits flush on the case top.}

More photos + STL files for the case + schematics + 3D STEP models: hardware/.

Home Assistant integration

Two routes — pick whichever fits your setup:

1. Native MQTT auto-discovery — the hub publishes auto-discovery topics; tanks appear in HA as sensor entities with zero setup beyond pointing HA at the same broker. Read-only.
2. HACS integration: SmartGhar — full bidirectional control. Every tank is an HA device with grouped Sensors / Events / Configuration / Diagnostic entities, plus a hub device with buzzer + LED controls. Capacity, sleep interval, samples-per-wake are editable from inside HA and ride the same MQTT command channel as the PWA, so both stay in sync.

HACS repo: github.com/Techposts/smartghar-homeassistant · Full setup + entity reference: HACS Integration wiki page

What’s NOT in this repo (and why)

This is the open-source TankSync firmware + hardware mirror. The hosted cloud dashboard (PWA at tanksync.smartghar.org) is a separate proprietary product that adds:

• Remote access from anywhere (no port forwarding)
• Push notifications to your phone
• Multi-tank history + insights
• QR-code device linking
• Multi-hub fleet management for societies, farms, hotels

The firmware works fully without the cloud — local web UI on the hub gives you tank levels, settings, OTA updates, Home Assistant integration. Cloud is opt-in convenience, never a dependency.

Licenses

Component	License	What this means
Firmware source (firmware/)	AGPL-3.0	Source through rx-v2.8.6 / tx-v2.0.15. Free for personal + community use; commercial users who modify and distribute must open-source their changes under AGPL.
Newer firmware (Releases)	Binary, proprietary	Versions after the line above ship as ready-to-flash .bin files. Free to download and flash on TankSync™ hardware; not redistributable or reverse-engineerable for resale.
Hardware (hardware/)	CC BY-SA 4.0	Attribution + ShareAlike. Build it, sell it, modify it — credit the source and share-alike.
HA Integration	MIT (separate repo)	Frictionless for HA ecosystem.

Why a source freeze + binary releases? The published firmware source (rx-v2.8.6 / tx-v2.0.15 and earlier, AGPL-3.0) stays open for hobbyists and HA users to build, audit, and fork. Development now focuses on the cloud platform, so newer firmware is distributed as binaries instead of source — the local-first experience is unchanged, and the in-browser flasher always carries the latest build. If you want a commercial firmware license for embedded use, reach out to the maintainer.

Contributing

Issues and PRs welcome. Read the hardware guide before opening hardware-related issues.

Author + brand

Ravi Singh (@ravis1ngh on YouTube) — solo-building open-source home infrastructure in India under the TechPosts Media / SmartGharLabs™ banner. Design, firmware, hardware, PCB layouts, and 3D-printed enclosures — all done in-house.

TankSync™ is part of the SmartGhar ecosystem (smartghar.org) — calm, local-first smart-home infrastructure engineered for real-world Indian deployments.

_{TankSync™ and SmartGharLabs™ are trademarks of SmartGharLabs.}