ESPiezometer - ESP32-C3 Field Validator for RS485 Piezometric Sensors

What it is

An open-source, battery-powered field tool built around an ESP32-C3 that lets hydrology technicians validate and calibrate RS485 Modbus RTU piezometric groundwater sensors on-site, before they're permanently installed. Instead of discovering a wiring or calibration problem after a datalogger has already been buried or sealed in a well, ESPiezometer shows raw and temperature-compensated water level readings live, on the spot.

Main components

• ESP32-C3 with RS485 Modbus RTU support and BLE
• RS485-to-TTL transceiver with automatic direction switching (no DE/RE control needed)
• TP4056 LiPo battery charge controller
• MINI-560 DC-DC converter module for the peripheral rail
• 0.96" I2C OLED display for on-site readouts
• 3D-printed enclosure with labeled switches, sized for field handling

What you can use it for

• On-site validation of RS485 piezometric sensors before permanent installation
• Detecting communication issues, wrong depth calibration, or wiring errors during a field campaign
• BLE logging to an Android phone with GPS-tagged CSV export
• A reference design for a compact RS485 diagnostic tool built around the ESP32-C3

Notes before use

• Nastrotek has not independently fabricated or tested this board yet.
• The upstream project has been submitted for OSHWA open hardware certification, is archived on Zenodo with a DOI, and ships with a published field test report and validation data — see the repository's 6_Validation_Data/ folder.
• The hardware license is split by file type: PCB design files (KiCad/Gerbers) are CERN-OHL-W v2, the 3D-printed enclosure is CERN-OHL-P v2, firmware and the Android app are GPLv3, and documentation/photos are CC-BY-4.0.
• All peripherals must share a common ground with the ESP32-C3; the RS485 transceiver needs no GPIO for direction control since it switches automatically.
• If you use this hardware in academic work or a derivative design, the upstream project asks that you cite it — see the citation block in its README.

Source / reference

Original hardware design by Armando Blanco (2025), archived on Zenodo.

Images and documentation on this page are attributed to Armando Blanco under CC BY 4.0. PCB files use CERN-OHL-W v2, the enclosure uses CERN-OHL-P v2, and firmware/apps use GPLv3 as documented by the source project.

How to evaluate this board

Read this resource as a starting point for review, not as a board you should manufacture blindly. Open the schematic first and identify the power input, regulator path, MCU or main controller, external connectors, programming interface, and any sensor or display interfaces. Once the functional blocks are clear, it becomes much easier to decide whether the design matches your project.

For ESPiezometer, I would focus the PCB review on the RS485 path, terminal-block labeling, field power protection, common ground assumptions, ESP32-C3 programming access, and test points for probing A/B lines in the field. A field tool needs boring, readable wiring more than a dense board.

Before reusing the files

• Check the license and original author notes.
• Confirm voltage levels before connecting external modules.
• Verify connector pinout against your cables and sensors.
• Review BOM availability before ordering PCBs.
• Export fresh Gerbers from the design tool if you modify anything.
• Treat untested designs as references until you have fabricated and measured them.

Good use cases

This kind of resource is useful when you want to study a real open-source hardware design, borrow part of a circuit, or compare layout decisions before creating your own board. Even if you do not fabricate the PCB directly, the schematic can still be valuable as a reference for power design, connector planning, enclosure constraints, or firmware bring-up.

For a small product prototype, the best workflow is to reuse ideas carefully: copy the principle, not the entire board without context. Mark what you changed, keep notes on assumptions, and add measurement points so the first fabricated board can teach you something useful.

Related reading

• PCB review checklist
• ESP32 schematic review checklist
• Net classes and trace width rules
• Ground plane basics for PCB layout