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I looked at the OS 2.3AC board and schematic and couldn’t find the overprotection. After some digging around on the forum I found a note that it uses a small value resistor but looking at os23ac_sch.png on github I can’t find any resistor for this but may have overlooked it. What resistor is it? Or is it only on later hardware? I looked for 3.x documentation on github but 2.3 is the latest I see. Please fill me in on the overcurrent details and were I can find documentation.
In looking this up I found that Autodesk is going to end Eagle in about a year. What’s the plan going forward? Convert to Fusion?
Overcurrent protection is a software feature — it monitors the current draw and triggers alert when it’s above a user-defined threshold.
On OpenSprinkler 2.3, there is a 0.2ohm current sensing resistor. I’ve just committed an image export of the Eagle schematic:
https://github.com/OpenSprinkler/OpenSprinkler-Hardware/blob/master/OS/2.3/AC/os34ac_sch.png
at the lower-right corner it marks ‘Current Sensing’. There, resistorRSis 0.2ohm.OS 3.x uses the same design, but replacing a single 0.2ohm resistor with 5x 1ohm resistors in parallel, because 1ohm resistors are easier and cheaper to source, and this improves the power dissipation upon large current.
As I said, the overcurrent feature is a software implementation built on top of current sensing. You can take a look at the OpenSprinkler firmware code and use generative AI to help you easily analyze the code.
Eagle is now part of Fusion. If you can’t install Eagle or Fusion, there are several EDA software that can import Eagle files, such as KiCAD, EasyEDA.
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