Reservoir has its first stable firmware release and a complete set of wiring diagrams. Three tanks, twelve sensors, one ribbon cable. Everything you need to build it is now published.
v1.0.0 is out
The Reservoir module now has a tagged v1.0.0 firmware release on GitHub. This is the same firmware that passed validation on real tanks earlier this week, packaged up and ready to flash. It supports up to three tanks (fresh, grey, and black water) with four contactless capacitive sensors per tank, giving you 25%, 50%, 75%, and 100% level readings for each.
Like every other TrailCurrent module, Reservoir runs on ESP-IDF, speaks CAN bus natively, and participates in the platform's auto-discovery protocol. Plug it into the bus and it shows up in Headwaters, Farwatch, and the mobile app without any configuration.
The ribbon cable wiring diagram
One of the trickier parts of building Reservoir is getting twelve sensor wires routed cleanly. The solution is a 20-pin flat ribbon cable that carries power, ground, and all twelve sensor signals in a single run from the ESP32-S3 board to the tanks.
The diagram maps every pin on the ribbon cable to its function: which wires carry 3.3V power, which are ground, and which connect to each sensor on each tank. Wires are grouped by tank (fresh, grey, black) so you can split the ribbon at the far end and route each group to its tank. Pins 6 through 9 are unused and reserved for future expansion.
Full wiring documentation
Beyond the ribbon cable diagram, the repo now includes a complete sensor wiring guide covering:
- Sensor selection: Any contactless capacitive water level sensor with a 3.3V digital output works. The XKC-Y25-T12V is a proven option.
- GPIO pin assignments: Every sensor maps to a specific GPIO on the ESP32-S3. The guide includes the full table.
- Mounting guidelines: Where to place sensors on the tank wall, spacing for quarter-level readings, and which tank materials work with capacitive sensing.
- Partial configurations: You do not need all three tanks wired. The firmware handles any combination and reports 0% for unwired tanks.
- Troubleshooting: Common issues like stuck readings, erratic values, and CAN bus problems, with step-by-step fixes.
Flash it from your browser
Reservoir is now available in the web flasher alongside every other TrailCurrent module. Pick Reservoir from the module list, plug in USB, and click flash. No toolchain required.
What is next
Reservoir is the newest module in the TrailCurrent platform and the first one dedicated to tank monitoring. With the firmware stable and the wiring documented, the next step is the case design and getting it listed on the build page alongside Headwaters and Bearing.
The full source, wiring diagrams, and release binaries are all in the Reservoir repo.