The moisture sensor works. Still some work to be done calibrating + tweaking signal levels to give it a wider range, but a swing from 350-450 (ish) is actionable. The first jump is where I discovered that I was using the wrong input voltage (5V instead of 3.3V). At the next leap, I watered then watched it decay over three days, watered again and watered near the very end.
Basically, this puts the moisture sensor at the same point as the temperature sensor – it is behaving correctly but still need some hardware tweaking to get the best possible accuracy + range.
I’m essentially building the system in blocks – bringing each piece to a basic level of operation before expanding into more grandiose plans. Right now, the sensors are working well enough on the breadboard, so I’m ready to bring more of the system on line. Next component – the water valves.
At the end of the day, all this system does is decide when to open water valves. My environmental inputs to that decision process are in place now to take care of the ‘action’ side of the equation. For now, I’m going to pick up two Orbit 62035 solenoid water valves and see what it will take to control them. From there, it will be a short hop, skip and a jump to a fully functional rudimentary system in place.
As with most of this project, I’m standing on the shoulders of those who have gone before. Ray has used a similar solenoid and posted schematics for it. The main component I’m going to have to acquire is the step up converter to give me 24V. Sounds like it is time for another SparkFun order!