Feature request – DC latching valve support

[evan71]

I am working with OSPi and was wondering if it would be possible to add a checkbox when setting up a station to select that it is a latching valve. With this checked it would bring up advanced features to select how long to bring the GPIO high to turn the valve on, then a new drop box would be available to select the GPIO that would bring the valve low again. You could also select how long this GPIO is on for.

Not sure what your plans are for the OSBee, but I would like to have options for more stations. I am doing some very basic testing and may be able to get something working, but need some options to get the latching valves to work. I would be curious if this is something that could be done or if you have other plans for a product with more station options.

Thanks for your help!

[Ray]

Now that OS 3.0 has adopted a modularized design (main processor board + solenoid driver board), the long term plan is to take the OSBee circuit and makes a latching solenoid driver board for OS 3.0. The driver board will then also be used for OSPi so that OSPi (in the future) can also have three different versions: AC, DC (non-latching), and DC latching. More specifically, there will be a Pi hat that consists of LCD, buttons, and a connector to hook up to the OS 3.0 solenoid driver board. The driver board will provide power to RPi, and receives commands from RPi to open/close solenoids. As this involves a lot of design work (like I have to redesign the OSPi enclosure and so on), it will take a while.

[darkspace]

Ray, can you please give us an update on when (or if) we can expect OS 3.0 with dc latching support? I’m waiting desperately to replace my Toro DDCWP-4

Thanks!

[Ray]

Hardware is ready but I am still in the middle of changing firmware to support the latching version. I would say perhaps we can start selling in a week or so. If you want you can go ahead to place an order of OpenSprinkler DC, and during checkout leave a note describing that this is for OS 3.0 Latch. We will ship as soon as it becomes ready. This way you don’t have to check from time to time when it’s going to be ready.

[darkspace]

Thats great news, thank you 🙂

[DrNeon]

Hi, I’m trying to build a system that works with latching valves from scratch (using ESP8266, some PCF8574s, the RTC, SSD1306, and so on) that runs the OS firmware, and I was hoping to get a little more information about the current firmware (2.1.8) support for latching valves, and the anticipated hardware configuration that works with the firmware. It seems that the firmware detects whether the system is latching or some other config (DC/AC non latching) via the address of the PCF8574 driver board; I think I have that working given the “LA” displayed during startup. What I can’t seem to find is the code that describes how the firmware controls the hardware outputs when hw_type=HW_TYPE_LATCH (inside OpenSprinkler::apply_all_station_bits() ?) Will there be a hardware schematic available for the OS 3.0 Latch configuration?

[Ray]

The related changes to enable latching board is now in branch 218.2:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/tree/dev-218.2
They haven’t been merged into the master branch yet, but will be very soon.

Technically, the way it works is as follows:

– each driver board type (AC/DC/Latch) use an IO expander chip (PCF8574 in revision 0 and PCA9555 in revision 1) that’s configured on a different I2C address (0x21 for AC, 0x22 for DC and 0x23 for Latch). This way, the main controller board (upper layer board) detects the I2C address to identify which type it is.

– The IO expander on Latch type has 3 signal control pins (BPE/BVE//COM) which are in charge of controlling the boost power enable, boost voltage enable, and common gate. Each zone as well as the common gate has an half H-bridge very much the same as on OSBee, allowing the gate to be connected to either ground or boosted 24V DC voltage.

– depending on whether you are opening or closing a zone, the code configures each gate accordingly, then boosts voltage, and supplies impulse current to a zone. This part of code pretty much follows the OSBee firmware code.

[raindance]

Hi Ray,
i am planning to install a sprinkler system in my garden and don’t know yet which type of valves to choose. (AC, DC, DC latching) What would you recommend for a new System, now that the Latch Version of OS is on its way?

[Ray]

Well, we are not expert on that, and it’s something you have to decide — you may want to consult with a gardener or landscaper or someone at home improvement stores. What I know is that 24VAC valves are the most common type, which you can buy online or at home improvement stores. Latching valves are less common, a lot of latching valves I’ve seen are for connecting to garden hoses, but there are latching solenoids which can replace 24VAC solenoids so that they can use the same valve body. DC non-latching valves are probably even less common than latching.

[raindance]

Ok, so I’ll probably get standard AC valves and a non-latching OS DC. Or maybe the OSPi DC… When do you think this will be ready for order?

[Ray]

There is no OSPi DC at the moment and it won’t be ready probably until the end of this year.

[Author]

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