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Sprinkler, heater, and air conditioning controller


#1

I’d like to use a microcontroller to control my sprinkler valves (8), heater, and air conditioning. For the human interface, I want to use Android phones and tablets and have them communicate with the controller over my home wifi network. I’m trying to figure out what the best route, hardware-wise, is going to be to accomplish this.

The Hydra seems like a decent option – with several modules attached:
1 x USB SP (plus external USB supplying wall wort)
1 x MicroSD card module (for logging historic data such as temperatures, relay “on duration”)
3 x GHI-SS-RELAY-GM-327 (4 relays each – for activating valves)
1 x Temp&Humidity module (for the house temperature reading for heater/AC control)
1 x ENC28 Ethernet module

Plus…
1 x 32 kHz crystal for a real-time clock (RTC)
1 x 1.2V (?) battery – for RTC (this one I’m not sure about)
1 x Pack of Gadgeteer assorted cables (for connecting modules)
1 x 30 ft length of 10-conductor cable
1 x Ethernet-Wifi bridge (which I already have)

All of this comes to around $300 shipped, which seems a bit steep for what I’m trying to do. Don’t get me wrong, I have no problem paying this amount for all this hardware IF this is going to be the best way to go.

Also, I already have an Arduino Uno board, which is currently not in use, but I feel that it would be more of a pain than it’s worth to try to do this project with it.

Although this will be my first “microcontroller” project, I’m an industrial PLC programmer by day and I’ve been programming in various languages (including VB .NET and C# .NET) for many years. I would appreciate any advice on how to approach this project.

Thanks in advance.


#2

In general, Gadgeteer is more expensive than absolutely necessary to solve a given problem. This is because Gadgeteer was designed for ease-of-use, reusability, and rapid prototyping, and was not designed for inexpensive implementations.

I have solved the sprinkler problem using a Panda II and a custom-built set of boards with optotriacs. I figure I’m into it roughly $100, but I could/would do it more cheaply (starting with a Cerb40) if I’d known then what I know now.


#3

For what you want to do you can use the Cerberus, but unfortunately it is still in Beta, and recommended for advanced users. the Hydra is in the same boat (Ethernet Stuff is still Beta)… for inexperienced users i would recommend the Spider, since the product is not in Beta…

Good luck.
Jay.


#4

I second Jay’s point about the Spider.

The Spider mainboard is $30 more than the Hydra, but Ethernet support for the Hydra is $20 more expensive. So, the Spider is actually only $10 more expensive. RTC crystal cost?

For your application, you don’t need the faster speed of the Hydra, and the Spider mainboard,in the near future, will be more stable with the GHI premium library.

Why the Hydra?


#5

You could probably accomplish what you want using a Panda II and the Connect Shield.
This gives you a controller, an ethernet interface, a realtime clock, and several JST connectors for connecting to relay modules or sensors.


#6

I was looking at the Hydra in the first place because of the lower initial cost, but you raise a good point about the Ethernet costs.

The crystal is a part of a $5 kit from Sparkfun, plus the additional shipping since I have to order it from a site other than GHI… The Spider still needs a crystal to be added, right?

The Cerberus looked like it would cut things too close on the number of sockets, since I will likely add to this controller eventually.

Taking a second look at the Panda II… it seems that the only hurdle that I would need to overcome with it would be the relay situation. Breadboard and SSRs? If so, which? Since the controller is cheaper, comes with MicroSD, power connector, RTC (including crystal?), and all sorts of I/O, wouldn’t this be a reasonable choice?

EDIT: Saw jasdev’s post after I posted this… Maybe I’ll look into the JST relay modules/sensors.


#7

I’m not much of a hardware person either, but there are a lot of experts on this forum that would be happy to help you. Also, there have been many posts about this topic.


#8

Getting out of the Gadgeteer world completely will save you a lot of money, if this is the sort of thing that will live on for a long time. Gadgeteer isn’t meant for production use. It’s meant for rapid and easy prototyping (and it’s good at that…)

For example, a Gadgeteer ENC28J60 module is $35. The chip itself is under $4 in ones. Breakout boards with this chip, the associated components, and the mags (jack) can be had for under $4 shipped, depending on who you’re willing to do business with.