OpenSprinkler › Forums › Hardware Questions › OpenSprinkler Pi (OSPi) › Using MQTT to log data › Reply To: Using MQTT to log data
I’m looking at interfacing this water meter http://www.dwyer-inst.com/Product/Flow/WaterMeters/SeriesWMT2 which would require a process or microcontroller to count the pulses. It could update a global variable in gv.py as well as publish it via MQTT… Don’t know anything about modbus, I have about a 150 foot run from the meter to the controller. I was thinking about a solar powered zigbee transmission link. I was also wondering if it might be possible to transmit the pulse information over one of the sprinkler zone wires. The wires would still have to work as the 24v actuator for the zone’s valve, but would also carry the meter pulse info back to the controller, saving me from having to run a long cable. Maybe wireless is the way to go. I’m happy to not reinvent the wheel, if there is something out there already.
Having status APIs is nice, but I’m particularly interested in state <i>changes</i>. I want know when someone has changed a program – say, a new daily schedule schedule. Or adjusted the zone time. It would be good to see time/week per zone, which be a good overall metric. And I want to go back and see what I was doing last year at this time… minutes/week (or gal/week) would probably be the best metric for this.</div>
<div>re: soil moisture sensing. This is a very complicated thing to measure. Simply measuring resistance is more a function of salt content than moisture. It is also dependent on the type of soil, plant, temperature, etc. Check out http://www.allianceforwaterefficiency.org/soil_moisture_sensor-intro.aspx</div>
<div>I happened to have attended the University of California, Riverside, that you mentioned. And as a further coincidence, I got my first job at the USDA Salinity laboratory, and my first taste of computer programming, doing soil moisture determination with the use of soil psychrometers. (see fig 13). This was a ceramic bulb (that simulated the root’s access to the soil) within which a thermocouple was placed. I’m a little fuzzy as to how it worked (this was 1968 🙂 There might be some interesting opportunity to do some microcontroller control of the thermocouple, and 3d printing for the psychrometer body, as well.</div>
<div>gotta run now, but I’ll get back on the ideas for the MQTT publishing points.</div>