Waterbot: water meter on the web

This (work-in-progress) project provides data collection and reporting for a pulse-output water meter. It's currently used at Permaculture San Francisco's 18th and Rhode Island Garden: here's the latest data.

What's involved

Skeletal docs follow; better info to come later. Feel free to contact Mike (email is in my profile) with any questions.

Hardware

You'll need:

• A pulse-output water meter: we're using this very reasonably priced stainless steel model from EKM Metering
• A Particle Photon to sense the meter pulses and connect over WiFi to report usage
• A Particle Particle Power Shield to charge a LiPo battery that runs the Photon
• A waterproof case to hold the electronics, with a clear cover so you can see the various LEDs for troubleshooting
• A solar cell that provides DC power for the Power Shield: we're piggy-backing off a 24V one the garden was already using for its pond pump

You'll also need access to a WiFi network. We have plenty of those in SF. (Particle also makes a similar "Electron" board that uses cellular instead of WiFi; you could probably adapt this project without much effort.)

Wiring:

• Connect the Photon's D2 and GND pins directly to the meter's pulse output
• Connect the Photon's VBAT to GND (yes, GND); this ensures the Photon initializes memory correctly on cold start
• Connect the solar cell to the Power Shield's DC input screw terminals
• (Optional, but recommended:) Connect the Photon's GND and RST pins to a pushbutton you can access relatively easily -- this lets you wake up the Photon for maintenance

Firmware

The waterbot firmware is loosely based on this similar project.

You should be able to build and flash it with the particle-cli tools or Particle's desktop IDE.

The firmware publishes events to the Particle Cloud:

• Whenever a meter pulse is detected, though at most once every 5 minutes. It will group together multiple pulses in a 5-minute period.

• At least once every 4 hours, even if no meter pulses are detected.

Once running the waterbot firmware, your Photon will try to enter deep sleep as often as possible to conserve battery. The reset button will wake it up for 5 minutes so you can perform maintenance.

There are constants near the top of the source to change the various timings.

Server

The waterbot server component runs "serverless" in the Google Cloud Platform, collecting data in BigQuery. There are two Cloud Function endpoints:

• dataCapture receives events from the Particle Cloud via a Pub/Sub Topic and stores the data in Google BigQuery

• report summarizes the data from BigQuery for use by the web client

To deploy your own (and yes, this all needs to get cleaned up and automated):

1. Create a Google Cloud Platform project and set up your Particle Cloud to publish to a Pub/Sub Topic in it. Follow Particle's GCP Integration docs.

2. Create a BigQuery table using this schema. Optionally populate it with any historic usage data.

3. Edit the server config to match your Google Cloud Platform project, and then deploy the two Cloud Functions using the comments at the top of each .js file.

Web client

The waterbot client component runs in a web browser and generates nice charts and scorecards from the server reports. Here's a live example.

Most of the client config is separated out, but there are probably some hard-coded links and references to Permaculture SF scattered around the code.

The client is (currently) a create-react-app project. Build it with yarn build.

The resulting build is a static site and can be hosted just about anywhere.