Project · hardware · in design
DWP Sprinklers
Wireless sprinkler valves you screw on, and then forget about. Most home sprinkler systems are wired through the yard; when a wire breaks, the zone dies. This replaces the wire: unscrew the old solenoid, screw on a battery-powered one, and a hub on the wall opens it over LoRa radio.
How it works
Three parts, one job: water the yard and leave you alone
- 1
Sprinkler Transmitter
A USB-C hub on the garage wall: an ESP32-S3 on Wi-Fi plus a LoRa module. It never transmits unprompted; each valve wakes about once a minute and polls it, and every frame is encrypted and authenticated.
- 2
Smart Solenoid
A battery-powered driver for a latching solenoid, sealed in the valve box with no wires to the house. Rev B, now specced, moves to 4×AA with a boost + supercapacitor stage.
- 3
App + cloud
A Next.js API on Neon and an Expo iOS app. Version one does one thing: water zone N for X seconds, or stop. A contract test runs the hub's real C code against the API. Scheduling and rain-skip are planned, not built.
The approach
Validate the production design before ordering a single board
Rebuilt, not redrawn
Both boards were reconstructed in KiCad from their Gerbers and netlist, and every fix is a reviewed, scripted edit that can be re-run — including a 0.03 mm sliver of copper KiCad had silently renamed, which hid a short.
The checks are tested too
Run against the board without its fixes, the design-rule gate fails on both defects it exists to catch. A fresh reviewer then checked every net, footprint and polarity independently; its findings shaped rev B.
Safety enforced by structure
The only way to open a valve takes a duration clamped to an hour, the node closes on its own timer even if the radio is dead, and a build check fails if code goes around those rules. A 300-command run at 40% packet loss never leaves a valve open past its deadline.
Where it is
- NOW
Both boards DRC-clean in KiCad; rev B specced
- NEXT
First run: five Smart Solenoids and five hubs, EU868
- THEN
Bench gates: ≤20 µA asleep, latching at end-of-life voltage, range from a wet valve box
- LATER
Volume only after all three gates pass