2 layers47 × 58 mm Water Tank Sensor, the printed circuit board in 3D

Water Tank Sensor

Compact ESP32 based water tank monitoring and control module designed for RV/Camper applications. Providing level, leak, temperature sensing and valve control. Integrates with display and optimised for low power.

Full screen GitHub .kicad_pcb

Size: 47 × 58 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 23
Nets: 25
Pads: 63
Tracks, vias: 127, 9
Pours: 2
Routed: Yes
KiCad: KiCad 6 (file 20211014)
Created: 24 Nov 2025
Updated: 22 Dec 2025

Overview

Water Tank Sensor is an open-source printed circuit board by RoBro92, from the RoBro92/SmartRV-TankPro repository on GitHub, published under the MIT licence. It is a 2-layer board of 47 × 58 mm with 23 parts on 25 nets, routed with 127 tracks and 9 vias.

It is built around the WEMOS D1 MINI and K7805-500R3. Its parts include 5 resistors, 5 connectors, 4 diodes, 2 capacitors and 1 IC. It belongs with the home automation and IoT and sensors and measurement boards and the ESP32 and ESP8266 boards of this library.

Main components

README

README.md

SmartRV TankPro (v0.2.0)

Open-source tank monitoring/control system for RVs/boats: ESP32-C3 controllers on each tank plus a Cheap Yellow Display (CYD) as the primary node.

Key features

Works over Wi‑Fi or Direct (ESP‑NOW) between CYD and controllers.
Fresh + Waste roles, max two controllers per display.
Live level/temperature/leak/fault telemetry and relay control (fill/drain).
On-device safety (fault detection, failsafe valve shutoff on comms loss).
Factory reset + direct-mode lock for secure pairing.
ESPHome-based controller firmware; LVGL-based CYD firmware.
Controller can also run standalone with Home Assistant (ESPHome integration).

How it works

Controller reads tank sensors, drives relay/buzzer/LEDs, and reports state.
CYD discovers controllers, assigns roles, shows status, and sends commands.
Link can be Wi‑Fi (UDP) on your LAN or Direct ESP‑NOW (channel 6) when no AP.

Repository map

hardware/controller/ – hardware overview + changelog (fabrication files in hardware/fabrication/).
firmware/src/controller/ – ESPHome controller firmware (README + changelog).
firmware/src/display/ – CYD firmware (PlatformIO LVGL) with README + changelog.
docs/ – reference guides/assets (see docs/README.md).
hardware/media/images/ – product photo, PCB renders, and CYD UI snapshots.
CHANGELOG.md – project-wide changes.

Getting started

Prebuilt binaries (v0.2.0): controller releases/v0.2.0/controller-v0.2.0.bin, CYD releases/v0.2.0/cyd-*-0.2.0.bin (bootloader/partitions/firmware).
You can also build from source if you prefer (commands below).
Hardware: see hardware/controller/README.md (parts, wiring, safety).
Controller firmware: firmware/src/controller/README.md (modes, pairing, flashing).
CYD firmware: firmware/src/display/README.md (UI actions, flashing).
Docs index: docs/README.md
Getting started guide: docs/getting-started.md
Roadmap: docs/roadmap.md
Beta testing: docs/beta-testing.md

Current limitations

Direct mode (ESP‑NOW) may not recover cleanly after a controller power-cycle; prefer Wi‑Fi pairing where possible. If Direct link drops, factory reset the controller and re-pair.
0.2.0 focuses on core functionality; UI polish and Direct-link robustness are on the roadmap.

Troubleshooting (quick)

Portal not showing: Direct lock active; factory reset (long-press pairing) to enable Wi‑Fi provisioning.
No telemetry: verify LEDs, ensure roles are assigned; re-pair or switch to Wi‑Fi mode.
Relay stuck: issue Clear Faults, then Fill/Drain again; power-cycle if still latched.
Direct link drops: re-pair or temporarily use Wi‑Fi; note the limitation above.
Need help? Open a GitHub Issue (labels: type:bug, type:feature, area:controller-fw, area:display-fw).

Demo videos

(placeholder links for quick demos)

Licensing

Hardware: CERN OHL-W v2 (LICENSE-HARDWARE).
Software/Firmware: MIT (LICENSE).

Category and platform

Home automation and IoT Sensors and measurement ESP32 ESP8266

Topics

campervan esp32 smarthome

Project files

Show this board on your page

https://pcbkit.io/boards/RoBro92/SmartRV-TankPro

The board's own page, for a message or a post.

Source

Repository: RoBro92/SmartRV-TankPro
Board file: hardware/legacy/v1-v2/V1 THT/Hardware/Water Tank Sensor.kicad_pcb
Commit: bab34dc
Licence: MIT

Parts

Qty	Value	Footprint	References
2	10k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R4, R5
2	1N4148	Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal	D1, D3
2	LOGO	logos:smartrv	G*, G*
1	1.5k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R3
1	10uf	Capacitor_THT:CP_Radial_D5.0mm_P2.00mm	C1
1	12v In	TerminalBlock_Phoenix:TerminalBlock_Phoenix_PT-1,5-2-5.0-H_1x02_P5.00mm_Horizontal	J5
1	22uf	Capacitor_THT:CP_Radial_D5.0mm_P2.00mm	C4
1	2N3904	Package_TO_SOT_THT:TO-92_Inline	Q1
1	4.7k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R2
1	470	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R1
1	K7805-500R3	SamacSys_Parts:K7805500R3	PS1
1	LOGO	logos:githubqr	G***
1	Power LED	LED_THT:LED_D3.0mm	D2
1	Programming port	Connector_PinSocket_2.54mm:PinSocket_1x04_P2.54mm_Vertical	J1
1	Relay	LED_THT:LED_D3.0mm	D4
1	Relay	Relay_THT:Relay_SPDT_SANYOU_SRD_Series_Form_C	Relay1
1	Temp Sensor	Connector_JST:JST_XH_B3B-XH-A_1x03_P2.50mm_Vertical	J2
1	Valve Terminal	TerminalBlock_Phoenix:TerminalBlock_Phoenix_PT-1,5-3-5.0-H_1x03_P5.00mm_Horizontal	J4
1	Water Level	Connector_JST:JST_XH_B2B-XH-A_1x02_P2.50mm_Vertical	J3
1	WeMos_D1_mini	Module:WEMOS_D1_mini_light	U1

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Questions

How big is the Water Tank Sensor PCB?

It measures 47 × 58 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Water Tank Sensor use?

23 parts, built around the WEMOS D1 MINI and K7805-500R3. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Water Tank Sensor KiCad files?

From the RoBro92/SmartRV-TankPro repository on GitHub, at the commit this page was made from: the board is hardware/legacy/v1-v2/V1 THT/Hardware/Water Tank Sensor.kicad_pcb and its schematic hardware/legacy/v1-v2/V1 THT/Hardware/Water Tank Sensor.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Water Tank Sensor design in my own project?

Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).