up:: Projects MOC
owner:: @Niko

Blocked on — three gates, in order

Nothing should be ordered for this project yet. It is paused, not stalled — each gate has a named owner action.

  1. Attic temperature log (running through August) → decides gateway siting. The gateway is rated to +55 °C and a Reno attic may exceed that. Cheap to measure, expensive to get wrong.
  2. No MQTT broker is installed on Home Assistant. Every path from a LoRa node into HA runs through it. Zero lead time, zero cost — but until it exists, nothing this project builds can report anywhere.
  3. Reference node not yet validated. Per the phased rollout, a DIY node is only trusted once it tracks a bought, factory-calibrated node across one full wet→dry cycle. The swale MVP comes after that gate, not before.

Do not order swale nodes first — they are the second track, and the first track proves the pipeline they depend on.

skills:: #MCU #sensor
lead:: @Niko
start::
estimated completion::

Project - Overview

ToDo:: Write Overview

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Purpose

To establish a comprehensive water flow tracking system across La Finka, aiming to measure and analyze water movement through different zones to enhance water management and conservation practices.

Objectives

Background Info

Expanding on La Finka's existing gravity-fed irrigation infrastructure by incorporating advanced measurement technologies to gain a better understanding of water dynamics on the property.

Project - Details

Scope

Implementation of water flow sensors at key points within the property's irrigation system, including data collection and analysis capabilities.

Milestones

A - Technology Selection

B - System Installation

C - Data Collection and Analysis

Tasks

Unblocks this project — do these first, in order

This project, once unblocked

Later

Recommended Stack & Swale Travel-Time MVP (260713, repriced 260804)

Site: 1.7 ac, 4000 Plumas St. Irrigation is gravity-fed. Home Assistant has been running since 260518 — power monitoring, smart switches, presence, and a Z-Wave stick that handles the door locks. Cat6 and a PoE switch with free ports already run to the attic, so gateway siting needs no new cable if the temperature allows it.

Radio → LoRaWAN. The far swale checkpoint is only ~250–380 ft from the house, but the right radio for battery field nodes is still LoRa — low-power, long-range, reliable at ground level through wet vegetation. WiFi is marginal at that distance through foliage and burns more power; Z-Wave stays on the door locks (wrong radio for spread battery field sensors).

Range is genuinely a non-issue at 1.7 ac — the link budget closes with ~69 dB of margin — but that is not an argument for skipping LoRaWAN. An earlier version of this note concluded "no LoRaWAN complexity required" and reached for raw LoRa on cheap ESP32 boards. That was reversed: raw LoRa wins at one node and loses at five, because a bare-radio node costs about the same as a finished LoRaWAN one once you add the carrier board, regulator and power management, and a second radio stack on the property is permanent maintenance. This project shares the property backbone; it does not build its own.

The travel-time trick. To answer "how long does water take to reach point X," you don't need moisture curves everywhere — you need a timestamped "water arrived HERE." Put a water-presence probe at each swale checkpoint (two stainless rods at the swale invert). HA logs the rising edge at each node during a release; travel time = Δ between node timestamps. Add a capacitive soil-moisture probe only where infiltration depth also matters.

Node topology — OPEN, gated on a measurement

The single biggest cost lever, and it is unresolved because nobody has measured the checkpoint spacing. One node's spare GPIOs can serve two or three rod pairs over direct-burial wire at ~$0.30/ft:

Head→mid→tail spacing Build Node cost
Under ~150 ft apart 1 node + 2 wired rod pairs ~$50
Over ~150 ft apart 3 separate nodes ~$138

Wire is cheaper but adds rodent and shovel risk, and a severed spur takes its checkpoint down silently. Above ~150 ft the wire costs more than the radio it replaces. Measure the spacing before ordering anything — it is a tape-measure job and it changes the bill by ~$90.

BOM — per water-presence node ≈ $46

Synced 260804 from Research - LoRaWAN Sensors (Smart Homestead) § Cheapest water-presence node. That note is the source of truth; if these disagree, it wins.

Part Price Notes
RAK4631 core (nRF52840 + SX1262) $17.99 LoRaWAN stack + power management done for you
RAK19003 WisBlock Mini base $8.99 30×35 mm; USB-C, LiPo charger, 5 V solar input
Two 304 stainless rods at the swale invert → GPIO ~$2 The actual sensor. Cut to length
IP67 box, cable glands, potting ~$8
Flat LiPo, JST PH ~$9

Gateway (shared, bought once): RAK7268V2 — $154. PoE, built-in network server, indoor-rated. Not on this project's budget — one gateway serves every LoRaWAN build on the property, so it amortises to ~$15/node by node ten. Alternative if it's ever revisited: Dragino LPS8v2, $222–308.

Siting is gated, not settled. Cat6 and a PoE switch with free ports already run to the attic, so if the gateway can live up there siting costs nothing — no new cable, no coax, no weatherproofing. The binding question is attic temperature and it is unmeasured. The RAK7268V2 is rated −10 to +55 °C; a Reno attic in August is often quoted at 140–160 °F, which would exceed that — though the PoE switch already surviving up there is evidence the real number is lower. Under ~50 °C peak → attic on an existing PoE port. Over it → indoors on an upper floor. Height is a nice-to-have here, not the reason: there is ~69 dB of margin to the farthest node, so elevation buys future reach, not coverage of 1.7 ac.

MVP cost — ~$205 or ~$292, depending on the topology decision above ($154 gateway + $50 or $138 of nodes). The gateway is a shared property cost, so this project's own share is $50–138.

Earlier figures in this note were wrong

A previous version quoted ~$35–40/node and a "$130–150 3-node MVP" against a Heltec/LILYGO ESP32 build and a $20 DIY receiver. Both were superseded when the LoRaWAN backbone was ratified. The build didn't get bigger — the earlier numbers just weren't costing the same thing.

Power & weather — non-negotiable: capacitive sensors, never resistive; IP67 + potted electronics + cable glands; deep-sleep between samples; sample faster once a node first sees water (~30–60 s adaptive cadence) to catch the wetting front sharply.

HA integration: each node publishes presence over MQTT; HA records timestamps; a template sensor / automation computes front-arrival per node and the Δt between checkpoints — so every release auto-produces a travel-time reading and a dashboard tile. ⚠ The MQTT broker does not exist yet (see the blocked-on callout) — this path is designed, not built. YAML for it lives in the versioned HA config repo and ships via the deploy script; it is never hand-edited on the HA box. See Smart Home & Environmental Systems Integration.

Where this sits in the rollout — two tracks

Per Research - LoRaWAN Sensors (Smart Homestead) § Phased rollout, Phase 1 runs two tracks in parallel, and this project is the second one:

The validation gate is the point. A DIY node that hasn't been checked against a calibrated one is a number, not a measurement — and a wrong travel-time reading is worse than no reading, because it will get used.

Decision (260713): LoRaWAN backbone, sensors-only — no Meshtastic comms layer for now. Buy-vs-make is settled per class: buy one calibrated unit per measurement type as the yardstick, make the fleet against it. Full sensor landscape, gateway siting analysis, and rollout: Research - LoRaWAN Sensors (Smart Homestead).

Project - Resources

Budget

Item Cost On whose budget
Swale nodes — 1 wired or 3 separate $50 or $138 This project (topology decides)
RAK7268V2 gateway $154 Shared property — one gateway serves every LoRaWAN build
ChirpStack + Mosquitto $0 Self-hosted
Calibrated reference node (Dragino SE01-LB) $146.50 Shared — bought once as the yardstick for all DIY nodes
Gateway siting $0 if the attic passes its temp log; ~$100–150 only if a roof antenna on coax proves necessary Shared

This project's own share is $50–138. Everything else is property infrastructure that other sensing builds reuse.

Materials & Tools

Equipment

References / Examples

Documentation and Media

Photos and Videos

Documents

Technologies

Questions / Unknowns

Collaboration and Participation

How to Get Involved

Potential Partnerships

Created: 260805-19:11

Updated: 260805-19:11