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Hey Ray,
can you clarify what you mean by the 5v terminal port:“2) OpenSprinkler has a +5V terminal port, it can be used to power the controller. Find a 5V mini UPS and connect it between 5V and GND and that will keep it running.”
Is that an internal connection on the AC version or the external VIN terminal which I understood was for 5v output?
After this discussion, I realized this option for redundancy is so easy and cheap, that I may implement it even if I may never need it.
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Yes, VIN is the +5V pin that’s internally wired to the +5V pin on the circuit. In older version of the enclosure, it’s marked VIN; in newer version it’s marked +5V. This pin is normally used to power certain sensors that require +5V. But it can also be used to provide +5V to the controller. You have to be certain that it should be regulated +5V (not to exceed 5.5V).
If you want to make sure current can only flow in one direction (e.g. from external battery into +5V pin and not the reverse), you can put a Schottky diode inline to control the direction.
Ok great. And to confirm, I can connect a regulated 5VDC UPS to the +5V / VIN connection in addition to the normal 24VAC transformer at the same time and OpenSprinkler can handle both? Or does it replace the need for the 24AC transformer.
And to also confirm, on the DC version of OpenSprinkler, the user can just connect a DC UPS (that supports between 7.5VDC to 12VDC) to the normal DC power plug on OpenSprinkler. No need to mess with the +5V connection on the OpenSprinkler DC model when using a DC UPS. That’s a big benefit for getting the DC version I guess.
1) Correct, you can apply regulated 5V to +5V (aka VIN) and GND on the terminal block. You can do so simultaneously with 24VAC transformer plugged into the orange terminal block.
Sometimes people are worried about two 5V sources (OpenSprinkler has an internal 24VAC to 5VDC converter) fighting with each other. This is usually not a problem because both are regulated, so at any time, the one that has slightly higher voltage will take over. But, if you want to absolutely avoid having two 5V sources at the same time, you can do the following: on OpenSprinkler v3, the leftmost pin of the orange terminal block is internally wired to COM (common). You can remove that wire from the terminal block, and also remove the COM (common) wire, then connect these two wires directly together, without going through any terminal block pin. This way, 24VAC will only power the solenoids (and NOT generating 5V via the circuit), and your external 5V will provide the logic level voltage to the controller. This will avoid two 5V sources competing with each other.
2) On DC-powered OpenSprinkler, correct, you can feed 12VDC directly to the DC power barrel (the polarity is center positive, side negative, which is the most common type). No need to mess with the 5V/VIN pin.
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