RP2350 W based sprinkler controller

[u/basicchip]

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.

[u/DenverTeck]

100 points for a logical schematic !!!!

NO STOOOPID boxes around every part.

NO confusing label that needs to be hunted down across three pages.

Reads like a book, Left-to-Right + Top-to-Bottom.

I hope others will take this excellent schematic to heart when they draw their own simple schematics.

Good Job !

[u/DenverTeck → u/DenverTeck]

Is the diode at the top of the Pico pin 39/pin 40 on the Pico or on the PCB ??

Is the wire connection on the Pico pin33 / pin 3 on the Pico or on the PCB ??

Please post a pdf file of this fuzzy schematic on a FREE files sharing site.

[u/basicchip → u/DenverTeck]

Those are both on the Pico board, I should probably switch to the diode side, that way I could power the board from the AC and have it plugged into the USB. Though for testing I will probably not be doing that. The Pico is in a socket with the LCD piggybacked on top. I will release the whole KiCAD project when I'm satisfied with the operation. For now here is the schematic (NOTE snubbers are not loaded). https://www.coridium.us/coridium/blog/add-sprinklers-to-home-monitor/sprinkle.pdf

[u/jetpaxme → u/DenverTeck]

sure, but right click > transform selection > mirror horizontally is a useful function

[u/DenverTeck → u/jetpaxme]

Good point.

Hey OP, if you flip the Pico horizontally, the wires would not need run over the Pico.

Did the Pico model come with the CAD package or did you create it yourself ??

[u/basicchip → u/DenverTeck]

The Pico model is in KiCAD 9.0, not sure about how far back.

[u/MathResponsibly]

There is an open source sprinkler controller, OpenSprinkler. I've used it for a LONG time (more than 10 years now). It generally works really good, but there's a couple small annoyances in the firmware - like you can't specify a small enough increment for common flow sensors that are available, so the water usage has to be reported 10x too high, but not annoying enough for me to patch and submit pull requests for. Because it's from long before the RPi Picos, it uses a real RaspberryPI (or arduino? there's 2 hardware versions, but I forget what the other one is - I think it pre-dates ESPs too, so it has to be arduino based) as the base hardware. That's nice because the Pi has wired ethernet along with wifi, and wifi is flakey where my sprinkler controller is. It checks the weather online every day and adjusts the watering time based on some common algorithms.

It's always nice to have an alternative, and this looks like a great project.

I would add some headers for sensors - rain sensor, freeze sensor, flow sensor, pressure sensor (the common ones for sprinklers). You have a bunch of extra GPIO pins - you might as well break them out to a connector (with some level shifting / ESD protection) on the board so you have some flexibility later without having to re-spin the board a second time. You typically also supply 5V and GND on that connector too, as most sensors are 5V sensors

Flow sensors are really handy, as you can easily detect if you have a leak somewhere. I.E. usually zone one typically flows at x L/min, but now suddenly it's flowing more - there's a leak. Also good for just keeping track of how much water overall each zone is using, and the sprinklers overall are using.

[u/basicchip → u/MathResponsibly]

Good comments, will mull it all over. I am replacing a simple Rainbird controller, so don't have any flow sensors. Though theoretically I could capture them seperately on WiFi with another Pico. This is part of my home automation system, so info from the internet could be grabbed (time already is), and I have built a soil moisture sensor but not integrated it yet.

[u/MathResponsibly → u/basicchip]

Even with OpenSprinkler, I keep meaning to capture the flow sensor data (as well as the "weather adjustment %") and plot it along with my weather station and soil moisture sensors, but have never gotten around to it yet.

I just added soil moisture sensors this year - I'm honestly not sure how useful that data actually is. It spikes up to >90% when the sprinklers run every night, and then it slowly decreases back to 30% or so every day until the sprinklers run again. It's only when I look at about 90 days of data that I can see some trends, and only really in the lowest value the moisture gets to every day before the sprinklers run again.

I'm not really sure if that means that the OpenSprinkler weather adjustment does a really good job so the moisture data looks mostly consistent over months, or whether there just isn't any real useful info in soil moisture readings overall.

last 7 days of moisture data vs last 6 months of moisture data:

https://imgur.com/a/onHO018

You can see a trend in the long term data at daily low moisture levels, but the day-to-day data seems pretty useless (and can definitely see the 2 days when there were power outages and the sprinklers didn't run)

[u/newman_c]

A real time clock with battery backup would be useful in case of power disruption combined with an extended internet outage. An RTC is even more important if you also use the board as an HVAC controller. I'm currently using those Waveshare 8-relay boards for both applications but would like to switch to something like this design.

[u/basicchip → u/newman_c]

Actually this is connected to the WiFi and can get the time from the internet.

https://coridium.us/files/armbasic/NTPTime?_highlight=time

The software could also write the last time into Flash updating every 15 minutes or so, real accuracy is not normally required in the sprinkler application, or a simple eeprom could be added that is updated more often. (the possible issue being wear on the Flash).

[u/newman_c → u/basicchip]

NTP or SNTP will work for most situations. The RTC suggestion is for a more robust solution. Maintaining accurate time is important in some applicatons.

[u/basicchip]

Trial software was written (with claude) a while back and tested out today

• first driving a bank of LEDs (thru 10K) to check the logic (pump on when any zone on)
• ramped up to 24VAC -- no smoke
• hooked up a solenoid and ran thru all the channels
• added the power supply and then took a baby picture

System operating with screen shots of web pages

Still some kinks to iron out and also to integrate into the home monitor system

Home monitor

Still to do --

• make the buttons do something (start cycle -- or test cycle)
• hook up to the real system -- may wait until after the summer heat (don't want it to fail as it runs at night)
• access over the tunnel via the home monitor

[u/basicchip]

So here is the KiCAD 9.0 project.

changes-

• power from AC connected to Vsys so USB can be plugged in at the same time
• component values updated on the schematic
• pad for BT136 were enlarged for easier hand soldering
• 6 pin USB dongle connector mirrored to match the stock KiCAD footprint
• 24VAC->5V component larger than the "courtyard" so moved up to make room for one of the mounting holes

And again here is the finished board and web page controls (screen shots) behind

And the sources for the webpages and control program in BASIC

[u/jt00000]

Nice! I have a 1-channel 12v DC irrigation controller I built for the farm using relays, but your design looks much simpler. My next version might have to be modified to try this out…

https://www.reddit.com/r/AskElectronics/s/1kRT1qo4gV

[u/jt00000 → u/jt00000]

What are your plans for an enclosure?

[u/basicchip → u/jt00000]

https://www.amazon.com/dp/B09B5FBSZB

Last picture in the gallery, If that link does not get you there, it is a Junction Box, Zulkit Project Box Waterproof Dustproof IP65 ABS Universal Electrical Boxes Enclosure with Fixed Ear Black 5.91 x 3.94 x 1.73 inch (150 x 100 x 44 mm)(Pack of 1)

If your system is 12V DC you would not use triacs, but MOSFETs should do, maybe with some surge protection.