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Introducing DC-Powered OpenSprinkler v3.4: : The First with USB-C Power

Oct 15th, 2025 by ray

Back in July, we debuted the AC-powered OpenSprinkler v3.4, featuring a new, redesigned enclosure and several hardware improvements (read here). Building on that, today I’m thrilled to unveil the upcoming DC-powered OpenSprinkler v3.4 — the very first OpenSprinkler powered by USB-C! Check out some sneak-peek photos below:

This model shares the same sleek, low-profile enclosure as its AC counterpart. This means it features a single-layer circuit board, two extra sensor ports (SN3, SN4), and an external Ethernet connector for easy installation of the wired Ethernet module.

The key innovation, however, is the move to USB-C as the power source. This change offers several powerful advantages, rooted in our goal of modernizing the sprinkler control circuit.

Why Move Away from 24 VAC?

Traditionally, most sprinkler controllers rely on 24VAC to operate sprinkler valves. This is a dated standard with several notable drawbacks: 24VAC power adapters are heavy, bulky, expensive, and difficult to source outside North America. For international users, finding a compatible 24VAC adapter for their country is a major pain point. Furthermore, their output voltage is unregulated and they lack current limiting circuitry, posing a major risk in the event of a short circuit.

The Origin of DC-Powered OpenSprinkler

When I designed the first DC-powered OpenSprinkler, my goal was to eliminate the dependence on 24VAC and switch to DC power adapters, which are lightweight, compact, inexpensive, and globally available. DC power supplies also include built-in current limiting and protection circuitry — making them safer to use and resilient to faults.

However, to work with standard 24VAC sprinkler solenoids, a DC controller must simulate the behavior of a 24VAC solenoid using DC-only voltage. Specifically, under AC power, a solenoid coil naturally limits its current through inductive reactance:
1. Inrush Current: When the solenoid first activates, it draws a high inrush current (500–700mA) to energize the plunger.
2. Holding current: Once energized, the solenoid requires a lower, stable holding current (200–300mA) to remain open. Under AC power, this reduction happens automatically because the the plunger (now moved in) increases the coil’s inductance, which in turn raises it reactance and limits the current.

To replicate this effect under DC, OpenSprinkler uses a 7.5VDC adapter as its main power source. Since a typical sprinkler solenoid has a coil resistance of 30–40Ω, this voltage naturally produces the 200–300mA holding current required to keep the valve open. To generate the initial inrush current, however, it uses an internal voltage booster to momentarily raise the voltage to 21VDC. This dual-voltage method is essential, because the high inrush current is necessary to reliably open the valve, but if applied continuously, it can overheat the solenoid coil and significantly reduce its lifespan.

Why USB-C is a Game Changer

The DC-powered circuitry is a proven innovation that has allowed users to ditch the outdated 24VAC technology for years. The new v3.4 now takes this a step further by adopting USB-C as its main power source. This introduces three key benefits.

1. Universal Availability

USB-C is a global standard for everything from phones to laptops. This makes sourcing the power adapter incredibly easy, no matter where you are. These adapters are powerful yet lightweight, affordable, and feature built-in protection circuitry.

2. Adjustable Voltage (USB-C PD & PPS)

Modern USB-C adapters are essentially smart, adjustable power supplies. Those that support the PPS (Programmable Power Supply) standard can provide a continuous voltage range (e.g., any voltage between 5.0V and 15.0V). This is a game-changer for optimizing sprinkler valve performance.

Different solenoids have different coil resistances and ideal holding currents. By matching the holding current to the manufacturer’s spec, you prevent overheating (from too much current) and unreliable operation (from too little). With v3.4, you can now calculate and set the ideal input voltage for your specific valves, and the controller will negotiate with the USB-C adapter to provide it. This level of customization ensures best efficiency and reliability. For example:

A 30Ω coil (older Orbit valves) with 250mA holding current works best at 7.5VDC
A 60Ω coil (newer Orbit valves) with 200mA holding current works best at 12VDC

In previous DC models, you would have to swap the power adapter to match the voltage. With USB-C, the controller automatically negotiates the optimal voltage from a single USB-C power source.

3. Mistake-Proof Design

Previous DC models used a standard barrel jack. Despite our best effort to prevent mistakes, some users would accidentally plug in a 24VAC adapter (simply because the plug fits in), resulting in damage. USB-C completely eliminates that risk: an AC adapter plug physically cannot fit into a USB-C port.

FAQ

Q: When will it be available?
A: We are now accepting pre-orders for the DC-powered v3.4, with shipments expected by mid-November 2025.

Q: How does the controller customize the input voltage?
A: It has a built-in USB-C Power Delivery (PD) chip that negotiates the requested voltage directly with the USB-C adapter.

Q: How can I determine the ideal voltage to set for my valves?
A: Multiply your valve’s holding current by its coil resistance. Example: 250mA × 35Ω = 8.75VDC.
The holding current is typically specified in the valve’s datasheet. The coil resistance is also in the datasheet, or otherwise can be measured using a multimeter.

Q: Can I use any USB-C charger? What if mine doesn’t support PPS?
A: If the adapter supports PPS, the voltage can be set precisely. If your adapter only supports fixed voltages (5 V, 9 V, 15 V, etc.), it will select the nearest match.

Q: Does v3.4 still include an internal voltage booster?
A: Yes. The controller still needs to reliably generate an impulse voltage (21VDC) for the inrush current, which not all USB-C adapters can provide. The internal booster remains, ensuring consistent performance regardless of your charger’s capabilities.

Q: How much current can it support?
A: This is determined by your USB-C adapter’s power rating. A standard 18W adapter can provide roughly 2A at 9V, while more powerful (30W) adapters can supply even more current.

Q: Can I still use my 7.5VDC adapter with a barrel plug?
A: Yes, you can use a simple dc-female-to-USBC adapter like the one shown below. It’s a simple pass-through converter and does NOT do any voltage conversion. However, note that the input voltage will be fixed at your adapter’s rating (e.g., 7.5V) and will not be adjustable.

Q: How can I power v3.4 using a 12VDC solar setup?
A: If your solar power source has a standard barrel plug, you can use the same dc-female-to-USBC adapter shown above.

Q: Which expander is it compatible with?
A: Fully compatible with DC Expander v3, just like previous v3 models.

Q: Will DC v3.3 still be available?
A: Yes, we will continue selling the v3.3 model while supplies last. In the meantime, we will keep offering the v3.3 circuit board without an enclosure for repairs and DIY projects.

Q: Can I reuse my existing wired Ethernet module?
A: Yes — it uses the same W5500 Ethernet module as v3.3.

Q: I recently bought an OpenSprinkler DC v3.3. Can I exchange it?
A: Yes, if your purchase was made within the last 30 days, it qualifies for an exchange under our no-questions-asked return policy. Please see our terms and conditions for details.

Tags: opensprinkler, usb-c

Posted in ESP8266, MakeBusiness, OpenSprinkler | Comments Off

Introducing OpenGarage 2.3+

Sep 9th, 2025 by ray

Exciting news! We’re preparing to release a new hardware revision of OpenGarage: version 2.3+. This will be the first OpenGarage to include native support for Security+ 2.0, eliminating the need for an external Security+ adapter. The hardware form factor is identical to OpenGarage v2.2, but with enhanced circuitry and software library courtesy of the open-source work of Ratgdo.

With this upgrade, OpenGarage can communicate directly with Security+ 2.0 garage door systems, enabling new capabilities such as reporting partially open status and controlling the opener’s light. Here’s a sneak-peek photo of version 2.3+:

FAQ

Q: What is Security+ 2.0?
A: Security+ 2.0 is a garage door opener technology introduced by Chamberlain around 2011 and sold under the LiftMaster, Chamberlain, and Craftsman brands. It uses rolling-code encryption for both remotes and wall button controls, providing stronger security and more reliable signals.

You can usually identify a Security+ 2.0 opener by its yellow “learn” button (and often a yellow antenna too). If you’ve purchased a garage door opener of the above brands in the last several years, there’s a good chance it uses Security+ 2.0. If you are not sure, take a look at your opener’s user manual, usually it will explicitly mention the term Security+ 2.0.

Unlike older systems, which worked by simply shorting the two button wires, Security+ 2.0 enforces the use of encoded signals. This allows not only open/close commands, but also richer feedback such as whether the door is partially open or the light is on.

Q: Why couldn’t earlier versions of OpenGarage support it directly?
A: Previous versions (like v2.2) relied on shorting the two button wires — which no longer works with Security+ 2.0. To control those systems, you had to use an external adapter (e.g., the Security+ 2.0 adapter that we sell) as a “middleman.” When the two wires on the adapter are shorted, it generates encoded signals accepted by the opener.

Q: What is Ratgdo?
A: Ratgdo (Rage Against The Garage Door Opener) is an open-source project developed by Paul Wieland. It allows a microcontroller (such as an ESP8266) to directly speak the Security+ 2.0/1.0 protocols via GPIO pins. In effect, Ratgdo replicates what a proprietary Security+ 2.0 adapter does — enabling direct open/close/stop commands, door status reporting, and even light control.

Q: What hardware changes are in OpenGarage v2.3+?
A: v2.3+ incorporates the same type of control circuits shared by the ratgdo community (see rat-ratgdo). It uses two MOSFETs — one for transmitting, one for receiving — to safely interface with the opener’s signal/button wire (typically 12 V DC).

⚠️ Important: Because of this design, v2.3+ is NOT compatible with legacy openers that use AC (e.g., 24 VAC) on the control /button wires. Using it on those systems could damage the circuitry. For those setups, OpenGarage v2.2 remains the recommended model.

Q: When will OpenGarage v2.3+ be available?
A: We’re now accepting pre-orders, with shipments expected no later than early October 2025.

Q: Does v2.3+ still use the built-in ultrasonic distance sensor?
A: Since Security+ 2.0 directly reports the door’s open/close status, there’s no need to rely on the ultrasonic sensor for that purpose. In Security+ 2.0 mode, v2.3+ will not use the sensor for door status, but it will continue using it to detect vehicle presence in the garage.

Q: Will OpenGarage v2.2 still be sold?
A: Yes. Since v2.2 is compatible with legacy openers, including both AC and DC systems (via its onboard solid-state relay), we’ll continue offering it alongside v2.3+.

Q: If v2.2 works with an external Security+ 2.0 adapter, why upgrade to v2.3+?
A: Two key reasons:

More features — v2.3+ enables additional features such as reporting partial open status and toggle the opener’s light, which Security+ 2.0 adapters can’t provide.
Lower cost — buying v2.2 plus an external adapter costs more than a single v2.3+.

Bottom line: Choose v2.3+ if your garage door system is made by Chamberlain, LiftMaster, or Craftsman. For all other brands, use v2.2. (Technically, any system with button wires that output DC below 20 V can use v2.3+, but it offers no benefit on other brands since they don’t support the Security+ protocol.)

Q: Can I modify my existing v2.2 to support Security+ 2.0?
A: In theory, yes — by adding MOSFETs and resistors. But unless you’re experienced with soldering, we don’t recommend it.

Q: What about Security+ 1.0?
A: Security+ 1.0 (mid-1990s–2010) was Chamberlain/LiftMaster’s first rolling-code system. It used colored learn buttons (purple, red, orange, green), but shorting the two wires still worked. Its status reporting is limited compared to 2.0. Ratgdo also supports Security+ 1.0, so with v2.3+ you can still read door status and control the opener’s light on those systems.

Q: I just bought an OpenGarage — can I exchange it for v2.3+?
A: Yes. Purchases made within the last 30 days qualify for our no-questions-asked return/refund policy (see our terms and conditions).

Summary

✨ With v2.3+, OpenGarage now natively supports the Security+ 2.0 technology — no additional adapters required, more features unlocked, and the same compact design!

Posted in OpenGarage | Comments Off

Introducing AC-Powered OpenSprinkler v3.4

Jun 22nd, 2025 by ray

Exciting news! We’re gearing up to launch a new hardware revision of the AC-powered OpenSprinkler: introducing version 3.4 — a sleek, refreshed take on the ESP8266-based OpenSprinkler. While it retains the same familiar circuit as the current v3.3, version 3.4 features a completely redesigned enclosure for a refreshing new look. Check out the sneak peek photos below!

TL;DR – What’s New in OpenSprinkler v3.4:

Single-layer circuit – Replaces previous 2-layer design to reduce assembly time and cost
Revised enclosure size – Lower profile and adjusted dimensions due to circuit layout change
Two extra sensor ports (SN3, SN4) – Added to standardize parts and simplify sourcing
Switched to power barrel jack – Easier power adapter hookup, no wire stripping required
Added external Ethernet connector – Simplifies wired Ethernet module installation

The most significant update in version 3.4 is the shift from a two-layer circuit design—consisting of a top logic board and a bottom driver board—to a streamlined single-layer layout. Originally, the two-layer design in OpenSprinkler v3 was introduced to support interchangeable driver boards (AC-powered, DC-powered, and Latch), allowing the same logic board to interface with various solenoid types. While this approach offered flexibility, it also made assembly more complex and time-consuming. In version 3.4, we’ve consolidated the design into a single board, significantly simplifying assembly and improving overall efficiency.

As a result of the single-layer layout, the enclosure height is noticeably reduced: from 33mm (1.3in) to 25mm (1in). The length is slightly reduced, and the width is moderately increased from 56mm (2.2in) to 79mm (3.1in).

The circuit design in version 3.4 remains largely unchanged from v3.3. However, one notable enhancement is the addition of two new sensor ports: SN3 and SN4. This upgrade is driven partly by the aesthetics of the new enclosure and partly by the decision to use the same 8-pin terminal block as the zone ports. This simplifies part sourcing and reduces inventory management overhead. Initially SN3 and SN4 will be inactive, and they will be enabled in a future firmware update.

Another improvement is the change to the power input port. The current orange 2-pin terminal has been replaced with a red-colored power barrel connector. Since most 24 VAC power adapters—including the one we provide—come with a standard plug, this change allows users to plug in power directly, eliminating the need for using an adapter cable or stripping wires, which has been a common pain point for some users.

Finally, an external connector for the wired Ethernet module has been added to the right side of the enclosure, making installation much more convenient. Previously, the Ethernet connector was located on the internal circuit board, requiring users to open the enclosure, plug in the cable inside, and route it through a small opening—a process that was quite cumbersome. You see, when OpenSprinkler v3.0 was first introduced, I didn’t plan to have wired Ethernet as ESP8266 already provided built-in WiFi. But in response to strong user demand, I improvised a solution by adding an internal connector and repurposed an opening—originally intended for a now-removed RF receiver—to route the cable outside. While the workaround was functional, it was far from ideal. With version 3.4, the enclosure finally includes a dedicated external connector, making Ethernet installation simple and user-friendly.

Below are side-by-side comparisons of v3.3 and v3.4:

Using OpenSprinkler DC with Power-over-Ethernet (PoE)

Jun 21st, 2025 by ray

Occasionally, we encounter application cases where users want to utilize Power-over-Ethernet (PoE), which allows a single Ethernet cable to deliver both network connectivity and electrical power. This setup eliminates the need for a separate power line, making it especially useful in remote or hard-to-reach locations where running additional cables is difficult. To enable PoE, a PoE switch injects voltage—typically 48VDC—into the Ethernet cable, which then carries both data and power. At the receiving end, a PoE-compatible power circuit is needed to step the voltage down to a usable level, such as 12VDC. OpenSprinkler does not natively support PoE, as its Ethernet module and power circuitry do not comply with PoE standards. However, you can use an off-the-shelf PoE splitter to separate the power and data: the splitter outputs 12VDC and a standard Ethernet signal (without the 48VDC). Since OpenSprinkler DC operates on 12VDC, this makes it compatible with a PoE switch when used with a suitable splitter.

The image below shows a typical PoE splitter. One end features an Ethernet receptacle where the PoE cable is connected. The other end splits the signal into two outputs: a 12VDC power plug and a standard Ethernet connector. The 12VDC plug connects to the power barrel of the OpenSprinkler DC, while the Ethernet connector plugs into the wired Ethernet module.

The diagram below illustrates the complete setup. With this configuration, a single Ethernet cable can deliver both power (for the controller and solenoids) and data connectivity. We’ve successfully tested this setup using a TP-Link 4-port PoE switch, a PoE splitter rated for 12VDC at 2A, and an OpenSprinkler DC with a wired Ethernet module—it worked flawlessly. Please note that this setup is only compatible with DC-powered OpenSprinkler models (including OpenSprinkler Latch), as they can operate directly on 12VDC. It is not suitable for OpenSprinkler AC, as there is no straightforward way to convert 12VDC to the required 24VAC.

Posted in OpenSprinkler | Comments Off

Why WireSprout only works with AC-powered OpenSprinkler

Aug 1st, 2024 by ray

Recently through a customer I learned about a product called WireSprout, and it only works with the AC-powered OpenSprinkler but not the DC-powered version. Out of curiosity, I looked into why this is happening. So what is WireSprout? Simply speaking, it allows individually controlling 2 zones using a single zone wire. This is useful in situations where some of your zone wires are broken and it’s too much hassle to repair the broken wires. Let’s say you have 2 zones, but only 1 good zone wire. Using WireSprout, you to control both zones using the single good zone wire. This works on any sprinkler controller (well, as you will see later, as long as it’s an AC sprinkler controller). A single WireSprout pack contains a pair of two ‘sprouts’. Each sprout is a tiny little circuit wrapped in heat shrink tubing, and has 3 wires: 1 blue and 2 green wires. Below is the diagram that shows how to connect it to a sprinkler controller:

To be fair it’s not adding more zones — to control 2 zones you still need to take 2 zone ports on the sprinkler controller. Also it requires the Common (COM) wire to be a good (i.e. non-broken) wire. But what it helps with is to reduce the number of zone wires. Note that it can only go with a pair of 2 zones. For example, if you want to control 4 zones, you need another good zone wire and another pack of sprouts. It unfortunately cannot allow you to control 4 zones with a single good zone wire.

Each sprout is very small, so likely it only contains a few electronic components. Also, it’s very general — it can work with any AC sprinkler controller, so the circuit doesn’t rely on the knowledge of any specific controller. It also works only for 2 zones at a time. Finally according to the customer, it doesn’t work with DC-powered OpenSprinkler, only works with AC-powered version. So it must rely on the property of AC to work. I googled similar products, and after a bit of research, it became clear to me that the circuit is indeed extremely simple. Each sprout is essentially two diodes in series, where the two ends are the green wires, and the center (between the two diodes) is the blue wire. Below is what I believe each sprout contains internally:

So how does it work all together? Here is the diagram:

Because the output voltage is AC, it has positive and negative cycles. As you can see, on the positive cycle of the COM wire, if Zone 2 port is on, the two diodes circled green will turn on. So the current flows from COM to Solenoid 1 through the Common wire, then through the zone wire to Zone 2 port. The other two diodes are reverse biased therefore solenoid 2 cannot turn on even if Zone 1 port is on. Conversely, on the negative cycle of the COM wire, the situations with all diodes are flipped, so only Solenoid 2 can turn on (assuming Zone port 1 is on). In this particular arrangement, Zone port 1 controls Solenoid 2, and Zone port 2 controls Solenoid 1. If you want them to correspond to each other (i.e. 1 -> 1 and 2 -> 2), just horizontally flip one of the sprouts.

In short, the WireSprout works by leveraging the fact that AC waves have positive and negative cycles. By using diodes, it can cleverly block half of the AC waves, therefore Solenoid 1 can only turn on during the positive cycles, and Solenoid 2 can only turn on during the negative cycles, or vice versa. Thus these two zones can be individually controlled.

Now it’s obvious why the DC-powered OpenSprinkler can’t work with WireSprout: DC-powered OpenSprinkler outputs DC-only voltage, there are no positive or negative cycles — there is only positive voltage. Therefore WireSprout can’t leverage the negative cycles to disable one of the solenoids therefore it cannot achieve individual control of 2 solenoids using a single zone wire.

There is possibly a downside of this method: each solenoid only get half of the AC waves as opposed to the full wave normally. Would this cause any reliability issues? I am not sure, but it seems there hasn’t been any reported issue so far.

Finally, we can also explain why WireSprout always works in pairs of 2 and not more than that: if you want to control, say 4 solenoids with a single zone wire, that would require counting the parity of the AC waves, which would be much more complex and may require an active circuit.

Posted in OpenSprinkler, Sprinkler Projects | Comments Off

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