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I guess doing this would mean running a pair of wires out to each sensor and then connecting each sensor to a GPIO pin. Of course you could use wireless but than means a visible sensor (think lawn mower) to find the sensor to change the batteries once every couple of years.
Whilst I love the idea of soil moisture sensors to regulate watering, this would be a heck of a retrofit for some installations. Nice though.
Mine is real dumb. It simply runs for ten minutes each day at 8:00 PM (so Mrs. rederikus can see it working – she has no faith in electronics) and I regulate the flow via small valves for the various plants in larger or smaller pots. It has only been running for a week and — so far — nothing has died.
I am glad that you have found a fault. It is very rare indeed for a wound solenoid to lower its DC resistance. It could still be a wiring error if you somehow have two solenoids connected in parallel. Almost certainly the extra load is dropping the voltage to the point where it falls below the level where the voltage regulator feeding the Pi cannot provide a stable 5 volts DC and, it falls over.
Remember that DC resistance (R) is different from AC impedance (Z). http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imped.html. That’s why I initially suggested that you measure the actual current drawn with an AC Ammeter. Nonetheless a 50% difference between one solenoid and the others would make me very suspicious indeed. I would completely remove the suspect solenoid and check it out of circuit. If it still exhibits the same problem then, it’s off to Home depot or Lowes.
Ray,
Thanks for all the info. I just looked at the Raspberry Pi website and they say here http://www.raspberrypi.org/introducing-raspberry-pi-model-b-plus/ that, “We think you’re going to love Model B+, but to ensure continuity of supply for our industrial customers we’ll be keeping Model B in production for as long as there’s demand for it.“
It looks as if you do not need to redesign your board in the immediate future (unless you want, of course). Just specify that you only support the model B and not the B+. For OSPi there is no requirement for the B+ whatsoever.
SInce you are looking for feedback on the product, here a couple of thoughts.
1). One thing that I have done on my 1.4 enclosure is to drill a number of 1/8″ holes along the long sides with the intent of increasing airflow. My OSPi is mounted vertically on an outside, East facing wall in the waterproof case you suggest. Doing this has lowered the CPU temperature by about 5 degrees. It is difficult to measure this accurately since the weather here in Charlotte NC is currently highly variable.
2). Please consider a built-in update option in the software. A button in the Settings page that, when pressed, would go off and download and seamlessly update the OSPi (just your software, not Debian) without having to dive deep into Linux.
My OSPi is now becoming boring since all it does is to sit there and just work. This is a very good thing since all I want it to do is to water my yard.
Thank you for an absolutely brilliant product.
We are currently having a summer storm here in Charlotte NC. My OSPi is showing the “Suppressed By Rain Sensor” message.
The trouble is, my irrigation system watered the yard last night at 4:30 AM. The Log says so.
There is no fault. Rather there is a problem with displaying current information on the Home screen whilst prior data is also displayed. The problem here occurs due to the Rain being current and the earlier irrigation program having already run. The fix is simple on paper. Simply paint the period where the rain is detected a different color on the background of the home screen graphical display. Like I said, it’s easy for me to write that but is it going to be worthwhile and/or excessively time consuming trying to code it? It would be a nice feature though.
One other way to do this could be to append the time the rain sensor detected rain to the end of the “RAIN SENSED” message further up the screen.
I am for the above too.
While you are at the code, would it be possible to log when the rain sensor is enabled and disabled? I ask this for two reasons:
1). to see such events actually logged in the log file.
2). I use a Rain Bird WR2 rain sensor and this has its own delays and options such as temperature low limit and depth of rainfall that stop watering based upon these settings. It also has an evaporative system (4 leather washers) that impose their own watering delay. These parameters are only viewable on the WR2’s screen.I think this topic is probably past its sell by date but here’s my 2 cents worth anyway. Looking at the picture of the valve assembly in the Amazon link the OP posted, it will probably be a lot simpler to just unscrew the DC solenoid and screw in a regular 24V AC device. Even if the OP has to buy a cheap complete valve in Home Depot, they only cost $12.
Another solution would be to run the OSPi on its usual AC and then put a 2 Amp bridge rectifier on the output. I bought 10 of these on ebay for $3.95 here http://www.ebay.com/itm/251555357618?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649. This would allow the OP to use a DC solenoid. Obviously he would need to ensure that the DC voltage was correct since 24VAC will produce in excess of 36VDC.
Perhaps an explanation will help.
You need about 24 Volts to run your valves and the electronics. This is produced by a transformer. The transformer does two main things.
1). It reduces (steps down) the 120 Volt AC mains power to a safer 24 Volt AC.
2). It is a transformer and is made by two separate windings of copper wire around an iron core. Which is why irrigation power supplies are fairly heavy when you pick one up. The two windings are known a primary, which connects to the mains and the secondary which produces the 24 Volts. There is no electrical connection between the primary and secondary windings. Coupling is entirely magnetic. This means that the secondary winding that you will use to power all of your irrigation system is a). at a lower and safe voltage and b). completely isolated and disconnected from the house mains supply.The amount of power (current) any given transformer or power supply gives is measured in Amps or, milliAmps. 1 Amp = 1000 milliAmps. Thus your 1500mA transformer provides 1.5 Amps. This is more than enough to run a couple of solenoids (Main and one zone) and the OSPi electronics. Power is really measured in Watts. Watts is a number that is derived by multiplying Voltage by Amps. Therefore your 24 Volt, 1500mA transformer may also be called a 36 Watt, 24 Volt transformer (24 * 1.5 = 36). Thus the more Amps you have for a given voltage, the more power in Watts you have available and, the heavier and more costly the transformer.
I have deliberately not explored AC vs. DC voltages because the OP was asking about the power of a transformer was AC voltage exclusively. In any event the wattage calculation is exactly the same.
I hope this explanation is clear. If you need more information, please post here.
Silly question. Are you running more than one zone (solenoid) at the same time?
Most transformers are designed to output about 1 Amp and that really means not more than two solenoids (main + 1 zone or, 2 zones) and the RaspberryPI-OSPi.
If you have an AC ammeter, try measuring the total current taken from the transformer at its output. That reading may give you a clue. Also try the same measurement when you activate each solenoid in turn. They should each draw about the same current when switched on one at a time.
Same here. Our house (Charlotte, NC) got a near miss two or three days ago. The flash and the noise were simultaneous. There was a pressure wave INSIDE the house. The power glitched and came back up. I have whole house surge protection but the OSPi lives in a Home Depot outdoor plastic case on the outside of the house. Its IP address vanished from my LAN. I just cut the power to it as it lives on its own breaker for a few seconds and it came back up again.
I think I was lucky this time.
Given that this security stuff if somewhat complicated and the penalty for getting it wrong is that either the security does not work or, one may lose access entirely I would like to suggest that some level of security is implemented on OSPi right on the SDCard image at some future release.
It would be even nicer if the security could be switched OFF at installation and a simple shell script be included that could be invoked by typing a single command such as “security on” (or security off).
All that is really needed is to have the Pi request Username and Password at each login. I know that both apache and nginx can both do this and can both remember the password on each machine accessing.
How this would work with the mobile app I am not sure.
Anyway that’s my suggestion.
Hey, thanks, Dan,
It would be neat if this could be incorporated into both the mobile app and the web interface.
I am still learning this device and am basically a hardware guy so, my favorite programming language is a soldering iron.
I bought an OSPi board and am now in the process of setting it up. I wanted some LEDS on each output and I also wanted to do a decent job of mounting the whole thing in an Orbit water resistant case.
My existing irrigation controller is a Rain Bird ESPMe and it has a Rain Bird WR2 wireless Rain sensor attached so I am also making provision for that to be properly connected without cutting the spade connectors off the cable.
The relay used on the board is a very small device. It would be better to make this little relay drive a bigger relay (yes I know it is cumbersome) and have that drive the solenoid.
There are two reasons for saying this.
1). the little on-board relay might do the job for a longer or shorter while, maybe forever. However if it does fail then you just lost your master valve so the entire irrigation system would stop.
2). It is easy to replace components that are not on the board. If the on-board relay fails then you will have to either replace the entire board or do some soldering iron surgery.+1
I too was hoping for this. scottsh has it right. If the weather forecast says it is going to rain, it might. If it says it is not going to rain, it might or, might not. The problem with ZIP code weather is that weather is just so fickle as to which parts of a given ZIP code it actually precipitates upon. Unfair really.
As scottsh says, a real world rain sensor is the only way that the system can be sure but
if it exceeds 70%, then it would set the equivalent of ‘raindelay = 1 day’ in the OSPi program.
Cool stuff.
Remember that the OSPi’s power supply is 24 Volts AC. It derives it’s power and the power for the Raspberry Pi from this base supply. Most irrigation transformers provide about 1 – 1.25 Amps AC which is sufficient to run the electronics and switch two sprinkler valves (Master and one channel). Most fans for electronics use are designed to run from a DC supply. The DC for the electronics is provided by a LM2596 chip which, why adequately powerful to provide enough power, has been implemented on the board specifically to provide a fairly small amount of DC power.
There is no heat sink on the LM2596 so heat generation is a consideration. Further the electrical noise generated by many fans may cause problems for the Pi. Given this and the limited overall power available “within the box” I would recommend that any extra fans are powered by their own, separate power supply.
@virtus wrote:
It sounds like you are interested in future capabilities, so I’d say the RPi is going to give you more options in the future. It’s quite a bit cheaper as well ($77 + $35/RPi + SD Card). Of course it’s not quite plug and play, but the preconfigured SD card really makes setup easy. It helps a lot to have some basic linux knowledge (if you have 3 Rpi’s already you’re probably good-to-go). Functionally, they are pretty much the same. With the RPi, you need to access it from another device (computer, phone, tablet) to do anything with it. The ATMega version has a screen and some buttons so many, but not all, of the options can be set from the device itself. It’s kind of nice to be able to see some information without having access it from another device.
If you don’t mind a little extra setup the RPi is what I’d recommend. I did the same thing last year – moved into a new home with an old sprinkler controller and I promptly replaced it with an OpenSprinkler Pi.
virtus, Thanks for your reply. This was exactly what I was hoping to hear. Having an onboard display is, as you say, quite handy. However I do not mind the OSPi being headless as I can either use the web interface, PuTTY or the mobile app – whichever seems appropriate to the task in hand really. I know Linux and the Pi OS quite well so I am already pre-disposed towards the Pi. I guess that’s the way I shall go with this little project.
Thanks again for your advice and opinion. It is much valued.
