I tried building one of these, but I got bogged down in the details instead of just getting it done simply. That's my problem I guess, I keep adding stuff and adding stuff and then it's turned into a monster
I'd built a
prototype; it worked well and I learned a few things, and then sent off to have some boards fabricated. They came back quickly and looked
awesome. I built one, programmed it, and it worked great... on the bench
In the field, I had problems with power. The sprinkler valves wanted 12-24 VAC, and the controller wanted 5 VDC. I tried building linear regulator with a rectifier to go from the ~18vac my transformer put out to the 5vdc the controller wanted, but it kept over heating, even with a generous heat sink because the controller took a rather generous amount of current at times (getting back to the over-complicatedness). So I tried to build a smps to step down the voltage. That didn't last too long, I hadn't protected the switcher well enough and transients from the valves killed it. I built another smps, better protected and heavier duty. This worked well, the events were running, the valves opening and closing on demand, etc.
Then the rains came. I knew water ingress would be a problem, and I tried to plan for it, but didn't do enough. The controller's keypad was built as a capacitive touch sensor, so I didn't need to drill any holes for it, however, the LCD display needed a portal. I very carefully cut a rectangle in my enclosure a little smaller than the lcd... then I carefully ground down the sides until the lcd just fit. After it was fit into its hole, I sealed both sides with outdoor rated latex caulk.
None of that mattered to the rain. One brief shower while I was away ruined it all. Rain filled the display and shorted it out, luckily not permanently. Rain also got into the controller board somehow, which was suspended inside the box on standoffs and shorted it out.
This year I plan to house the controller indoors. It will have it's own 5v power supply, and live in my crawlspace.
Here's the pcb ... it's got more bells and whistles than most could shake a stick at, yet it can't protect itself from water ingress! I don't have any pictures of the controller put together as my camera crapped out while I was working on it.
https://projects.dimension-x.net/pictures/sprinkler/pcb5_cmp_aft_sm.jpg