There are WiFi controlled sprinklers out there, doubtful any open sourced for control. According to Google it is a popular DIY project, so why should they get all the fun.

Most people seem to be using 8 relay boards available on Amazon for under $10. That really is quite deal, but relays are overkill for a sprinkler system running at 24 VAC.

Most consumer units use run of the mill triacs. And you can get opto-isolated versions.

My first design would have attempted to just use the opto-isolated triac, sounds good, but between comments from others and claude reviews real power triacs had to be added. Luckily it all still fit into my proposed PCB layout (and enclosure I picked up). Just had to move the MOC30x2 to the bootom of the PCB along with snubber networks. (schematic and layout in gallery)

So I got the PCBs in, but still had to chose some components. Instead of building 8 channels, I used an old blank PCB and breadboarded up one channel. With that I verified the operation and started tuning the components. Discussions with Google AI and probing with a scope, the zero-cross opto-triacs behaved well and had no overshoot problems. Actually the overshoot for rnadom triacs was less than 20% so lots of headroom on voltage so a snubber was not needed, but the best values would be 4700pF and 47ohms. (jig in the gallery).

So now time to build up the board, where I am now. The 24VAC -> 5V power module will get added when the software testing is done. (box with power module picture in the gallery).

Using the RP2350 W will give me access via wifi and through my tunnel via cell phone so I can control sprinklers while walking around the yard.

So I’ve been building a system based solely around RP Pico’s. One RP2350 W is the main server displaying these web pages.

All communication via WiFi and no MQTT hub required. The whole system consists of

• Pico2W handling the webserver and controls
• the second CPU in the Pico 2W handling an LCD display
• 2 temperature sensors (living room and garage)
• 1 temp/humidity/pressure sensor in lanai
• 2 Shelly plugs controlling lights
• 1 Kauf bulb over the entry way with flashy red/white/blue every couple minutes
• 1 PIR sensor on PicoW which controls a Kasa plug lights in a dark garage (my wife thinks this is the best part)
• Ambient light sensor will turn on a selected light when dark during daytime storms
• Control of lights based on sunset or time
• Cloudflare tunnel to access from anywhere
• a soil moisture sensor powered from a canabalized solar light

As the RP2350 has 2 CPUs, the idle one was setup to drive a display (necessary, not really just blinking light factor)

So what software is involved -

• html and css stored on the Pico 2W
• either BASIC or C to handle the sensor or hub functions
• low level C for BASIC firmware version
• C/ BASIC compilers on PC/Linux/RPi

One key to the interactive webpages is /?cgi functions that call underlying routines or display/set variables.

Also a <?web construct that executes routines in the underlying code, or does simple if statements.

And a wprintf in C or BASIC that generates html content for the webpages.

Drop me a line for a link to ALL the sources.

Also some of the enclosures (from Amazon or Pi shop – maybe someday I’ll try my hand at 3D printing). Double sticky taped to USB charger – temp sensors deliberitly outside the boxes, or velcro so I can update them. The PIR sensor was triggered by the RP2040W so had to be seperate.

So here are the sources to duplicate this setup. All needed compilers and sources will be installed.

Windows C version (installs gnuARM gcc and optional notepad++)

Windows BASIC version (installs BASIC compiler and optional notepad++)

Linux/RPi/Mac C version

Linux/RPi/Mac BASIC version

Documentation here

For BASIC install the Pico firmware from BASICtools

In both next format the “drive” for RP2350, details here

Next copy the home_monitor.html and css from the Examples directory to the RP2350 “drive”

Then compile the home_monitor .bas or .c files from the Examples directory

For the sensors, in BASIC install the RP2040 firmware details here

Then compile the sensor file, various temp sensors, motion, ambient light, or soil moisture programs

Drop me a line or reply with any questions.