Open G-ECU (grow electronic control unit)

een · Dec 12, 2006

Hi,

I want to make an electronic controller for hydro growers...

The priorities in order are:
* Address *basic* needs of hydro growers, but nothing more
* Cheap
* 'Open' design
* Can be hand-assembled

These are the features I have decided on... comments?

* 'Open' design, all hardware and software design is free. (Except for a more tricky version of software which I charge $ for)
* Free C compiler. At the heart is an Atmel ATMEGA644 microcontroller which has a free C compiler and excellent libraries, so anyone can write software for it.
* All 'through-hole' parts, can be easily assembled by hand
* Vast majority of parts are available at local electronics store or at least an on-line distributor farily cheaply (target prices is US$100 max. not incl probes)
* pH input, can measure pH fron standard BNC connector pH probe to +/- 0.1 pH
* EC input, optimised for sensor constant K=1 but user can vary it (i.e. make your own sensor)
* Humidity, good for 5%, probably 2%
* Light sensor, so you know if your light is on/off/faulty
* Big light switch, 30A resistive, 6A inductive (can probably handle 10A), replaceable with larger external relay
* Fan speed controller, good for 2A (or about 200W on 120V, 400W on 230V)
* 6 x 12A general purpose relays, for things like flood/drain pump, can be wired to do light flip-flop etc
* 6 x general purpose low-voltage digital inputs, for things like float sensors
* 1-wire bus, can add all sorts of stuff, but mostly temperature sensors
* Can plug in a standard 16x2 LCD character display (with backlight) or status LED
* Buzzer

Here is an 'architectural' diagram

bazooka · Dec 12, 2006

Are you looking for help or just input?

fshwcrs · Dec 12, 2006

i was thinking about something like this the other day. instead of charging for the software, maybe sell completed kits instead. you can copy software, but people will pay for convenience.

een · Dec 13, 2006

bazooka said:
Are you looking for help or just input?

Just input really, but I'm open to all ideas...

In fact, enclosure, what box would you put it in? I can make it mount in an ATX case but that is huge overkill. I will probably just put a 4mm hole in each corner, then you can clip in sticky-pad type mounting posts that will let it mount in any box with a flat surface.

een · Dec 13, 2006

fshwcrs said:
i was thinking about something like this the other day. instead of charging for the software, maybe sell completed kits instead. you can copy software, but people will pay for convenience.

I was thinking I could sell 2 versions of a kit, one with basic open-source software, and one with licensed software. The only difference is the software that is on the chip when it's shipped, the open source version is able to be updated by anyone through the serial port, the licensed version is code protected and will only accept an update that has been encrypted with the right key.

I forgot to mention a feature; it has an RS232 port for connection to a PC, which allows control from your PC, datalogging, etc, and easy updates without needing a programming adapter. USB is no good because cable length on USB is limited to 5m so you would have to bring your PC to your grow, or vice-versa. RS232 can do 30m pretty easily. Modern PC's may not have RS232 ports but you can get a USB to RS232 adapter for about US$15.

The open source PC software will be written in C# using the free 'express edition' of visual studio from microsoft. I would write it in Java except I find that very hard, as would everyone else I think. The licensed PC software would be written in C++ because you can't reverse engineer it so easily.

Rare Groove · Dec 13, 2006

I've been thinking about something along these lines for quite some time. Just a simple grow controller. Was wondering if something like a BASIC stamp (already a proven circuit design) would be powerful enough to run something like this. Haven't thought much deeper than that on it, but would definitely be a cool thing to have.

I'd be interested in seeing a kit that includes the PCB, all the components, and the software to load onto it. That way cost would stay low, and for DIYers it would be something really cool to assemble but not so complex as to require programming your own software, etc. Maybe even sell the kit and/or assembled units somewhere like eBay. I'd definitely like to see something like this available in some form though.

Just some thoughts :joint:

een · Dec 13, 2006

I know the hardware will work because I've already proto'ed it, at least the hard bits... True, no one will really want to write their own software so I will provide enough with the open source version to keep 99% of people happy.

You'll be able to download the CAD files so you can order your own PCBs made and buy the parts yourself, otherwise you can buy it in kit form, but most will want it assembled which I can do also. Then you just have to mount it in a box and connect your pump, lights etc

The Dopest · Dec 14, 2006

theres been alot of talk on this subject but it seems to fall dead shortly after the hype...i know alot of people like me that are interested in this soooo....

bump

een · Dec 15, 2006

The Dopest said:
theres been alot of talk on this subject but it seems to fall dead shortly after the hype...i know alot of people like me that are interested in this soooo....

bump

I've been reading OG since '01` and know exactly what you are talking about. I promise that by Feb I will have photo's of an assembled prototype.

Last addition is a battery backup input, so if the power goes out the micro can keep time until the power comes back on again.

DB2004 · Dec 17, 2006

There are several models of PLC (programmable logic controllers), that will do what you're planning....

Best Regards

DB

Mackawber · Dec 17, 2006

I hope you are going to have some heavy duty relays to handle up to 30 amps to control lights!
(Big light switch, 30A resistive, 6A inductive (can probably handle 10A), replaceable with larger external relay)

een · Dec 17, 2006

DB2004 said:
There are several models of PLC (programmable logic controllers), that will do what you're planning....

Best Regards

DB

PLC's cost more than $100 and will need extra circuitry to interface to the sensors.

een · Dec 22, 2006

Here are the schematics of the design for those that are interested:

een · Dec 22, 2006

een · Dec 22, 2006

Bah they are all different, see them in full in my gallery (I hope)... I have 3 uncommitted inputs to the CPU. These could be for example:
- extra 2 relays
- extra 2 inputs
- 3 buttons for LCD display
I am leaning towards buttons for the LCD display, any other ideas?

ALso, I have started laying out the PCB in 5x5", so it will fit in a standard 6x6" junctions box. If anyone can think of a better size, speak now, because it takes a long time to lay out a PCB.

The Dopest · Dec 22, 2006

im still here...if you need me ill be over here smokin

clowntown · Dec 25, 2006

Tagged.

I hear Growtronix has been having a lot of trouble getting units out in timely manner. Maybe if you jump on it real quick and have a decent, flexible system out with a basic, working piece of software that can be updated with new features/fixes quickly... you could possibly take over.

I know DeadlyFoez would be interested for sure...

Ron Burgundy · Dec 25, 2006

clowntown said:
Tagged.

I hear Growtronix has been having a lot of trouble getting units out in timely manner. Maybe if you jump on it real quick and have a decent, flexible system out with a basic, working piece of software that can be updated with new features/fixes quickly... you could possibly take over.

I know DeadlyFoez would be interested for sure...

I think that the pH/TDS res meter is on a 16 wk delay. That is a long time.

I'd be very interested in your product if you sold it as a kit, because it is often dificult to get small individual electronic components depending on where we're located, and also because if i just need a .99 resistor or something, shipping will be more than the whole unit. I wouldn't mind soldering the board together or doing whatever i have to do.

Also, will i be able to link it to a computer? I dont know if you mentioned that.

een · Dec 26, 2006

Ron Burgundy said:
I think that the pH/TDS res meter is on a 16 wk delay. That is a long time.

I'd be very interested in your product if you sold it as a kit, because it is often dificult to get small individual electronic components depending on where we're located, and also because if i just need a .99 resistor or something, shipping will be more than the whole unit. I wouldn't mind soldering the board together or doing whatever i have to do.

Also, will i be able to link it to a computer? I dont know if you mentioned that.

Yeah I'm sure no one will buy a plain PCB. Parts like relays come in so many shapes and sizes it is hard to design in one that can be purchased easily world-wide. So the only real demand I think will be for kits, and more likely, built+tested PCBs.

It will be able to connect to a PC with RS232 (I chose RS232 because you can get much longer cable lengths than USB). RS232 also allows connection to land-line and GSM/CDMA (whatever your local standard is) modems, Telaire CO2 sensors, etc :yummy:

clowntown · Dec 26, 2006

Well, get to work! :whip:

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