I have a Rainbird WR2 Rain/Freeze sensor. It has a 916 MHz radio link to a small receiver that is hard-wired into the Hunter controller. No idea what that protocol is, but this was the standard setup for the company that installed the system. My guess is that there is some kind of industry standard comm at work here. The sensor is powered by an internal coin cell.

ak

 

Hello everyone,

This is an interesting thread I was heavily into this some years ago.

Since then I moved to the mini computers or some call them micro computers. They are small boxes that have complete systems inside that include real high end CPU's made by Intel and AMD. One is less than 5x5x3 inches in size, yet it runs Windows with ease and I can do anything with it that I did with any of my previous systems, but take up much less room. My full tower was HUGE compared to these smaller ones. I could fit probably ten of these inside a full tower and have a mini super computer.

Anyway, the main point is the power consumption which is around 6 watts maybe up to 15 watts running all 4 cores. The main interface is USB so if you want to run RS232 you have to use an RS232 to USB adapter. RS232 is easier to use than raw USB so that's not a bad idea when we want to control things and get inputs from sensors.
You do have to either write your own human interface but I program in Windows so that's not too big of a deal, but you can probably buy software for this too.
For an example, I had a complete system for monitoring the automobile car voltage 24 hours a day 7 days a week and logging on the computer so I could work out what was going on day to day. The car unit measured the voltage and current and set that data over the air to a receiver in the house, and that had an interface to the computer using an Arduino which made the electronics/computer interface much simpler. The Arduino did RS232 and my interface just read that data.

These computers are made by various manufacturers including GMK which offers incredible customer service, but I think most of the others do too. The one I use now is not a GMK but I do use a GMK for something else. That one is just about 4x4x2 inches and yet it runs Windows 11 just like the others.
It's amazing how they did these little computers. They have top of the line CPU's in them, fast RAM, and SSD drives.

Of course we can't forget about the raw Arduino. If you can program those you can automate just about anything with ease, and then all you need with it are the sensors and some sort of display which come cheap. You may also want to get some actuators depending on the task. If you don't program you may want to learn

 

Cruts;
After much reading I have decided to purchase this same unit. However I do have a question: How does this unit adjusts the watering during rainy days? The brochures mention something related to "Smart Weather Sense", which sounds to me like advertising jargon. Is it really something useful?

It delays the watering if the weather report says it has rained, so of moderate usefulness.

 

I didn't see anyone mention ESPHome.

Now that is it tightly integrated into Home Assistant, it's a pretty amazing option.

 

I didn't see anyone mention ESPHome.

Now that is it tightly integrated into Home Assistant, it's a pretty amazing option.

It's great. I enjoy the complex parts of firmware development of my own systems.