This link is just an example and is just one of quite a few shields I will be gathering for my desired project. On this shield there is a single BNC connector that connects to a PH/ORP probe for measuring the ph of a solution. However, for my project, i will be needing several probes of varying types as well as several other forms of sensors and things like this.
My question is can a shield like the one in the above link be modified in such a way that it can monitor/control more than just one probe connection? Like can a sensor shield be used in conjunction with the PH shield to expand the PH Shield's ability to monitor/control several PH/ORP probes?
I am wanting to build an indoor gardening controller (just like Billies Controller), but I am wanting mine to be able to monitor and control a few different growing rooms and the reservoirs that feeds plants at various ages and nutrient needs so I figure as many as 7 reservoirs. Each reservoir would need a temp sensor, water level sensor, EC probe, PH/ORP probe and a DO probe. That's 5 different sensor/probes per reservoir and if I need to use an individual shield for each and every sensor or probe, I am looking at about 35 shields I would need to connect to my mega.
So I am hoping someone can first affirm that these shields can be made scalable, and secondly can you point me in the right direction of how I might best accomplish this?
This thread apparently piqued little interest. I am finding bits in pieces of a possible solution, but being as new as I am, I am unable to determine what would be applicable or not. So far, my research suggests that this can be done, but I would likely have to design my own shields to be used after other shields to give each shield a multiplex capability. I am unsure if it would need just a multiplexer, or if shift registers would also be needed. I hope there is a firm somewhere that helps people such as myself build a new shield when all I have at the moment is the generalized idea of what it would need to do. For the PH shield, the expansion shield would need to first need to connect via a BCN lead (if possible), the Arduino would need to know how to route a signal through the ph shield then through the multiplexer to the individual probe that is being tested. Once that signal returns back to the Arduino and that data is logged, the process would have to start over again, this time with the signal being routed to the next PH probe is a different solution.
When it comes to peripheral items, you are not likely to get what you want with a store bought shield, but there is a swag of prototyping boards available to make your own. There is no obligations to use a shield per se anyway. If you have a lot of connections, it may be more convenient to have a separate board of any size that run ribbon cables to a proto board that is simply being used as a multi-connector
Thanks for the quick education Nick! Would it be good for me to then attempt to rebuild their shield by reverse engineering? To my knowledge, they are the only company that has built a PH shield for production and it is proving difficult to locate a datasheet on that shield so my options are kind of thin right now.
Aside from this particular shield, would the concept you mentioned also apply to other shields that would otherwise be needed for my project? Also, do you believe that a single Mega w/Ethernet Shield with a 16GB microSD card can handle the burden of operating so many devices?
.zip is a compressed file. If you download this free program it will "unzip" them for you but then you will need a program like Eagle to view these unzipped files
myggle:
Thanks for the quick education Nick! Would it be good for me to then attempt to rebuild their shield by reverse engineering?
Reverse engineering sounds a bit fast and loose but, yes, you probably can merely by tracing the tracks on the board. It may also be unnecessary. All you really need to know is the signal and power characteristics and you can cobble your own from scratch. You can also simply pay the $$$$$ and simply stack several single probe shields, but you still need to know the power requirements. I raise this particularly because there appears to be a regulator on that board, which does suggest a substantial power requirement
Aside from this particular shield, would the concept you mentioned also apply to other shields that would otherwise be needed for my project?
Yes. You can make whatever you need. Most of mine consist of - 3x headers for temp sensors, 1 x water flow, on-board clock, headers for bluetooth and and I2C LCD. No amount of money will see you with a store-bought that can do that.
Also, do you believe that a single Mega w/Ethernet Shield with a 16GB microSD card can handle the burden of operating so many devices?
A mega should be fine and I will be surprised if you need more than 2Gb. If you really need 16Gb, your project is probably too big and/or fast for Arduino, and I bet it isn't!
Thanks Pedro, I can unzip, it was Eagle that I didn't know about, but I will get that and have a look see!
Nick, thanks again, you may have shaved months off my research direction. After yesterday's dialogue, Iput a little thought into exactly what all I needed controlled and this is what I came up with;
--------------------------------------------------------DC power needs------------------------------------------------------
7 - 12VDC Plastic Solenoid Valves (n.c.) (triggered to empty spent nutrient reservoirs into master waste line)
8 - 6VDC peristaltic dosing pumps (to mete nutrient into water lines User/probe value controlled)
7 - PH Probes (collects acid/base data and dictates functions of peri pumps)
7 - EC Probes (collects electical continuity data and translates EC to TDS in PPM)
7 - DO Probes (collects dissolved O2 data)
7 - water level Probes (collects consumption data)
7 - water temp Probes (collects water temp data)
5 - DHT22 temp/RH sensors (dictates alarm and other functions from AC fans)
5 - CO2 sensors (dictates room air exchange)
5 - photo sensors (detects light leaks)
3 - Odor sensors (also dictates room air exchange)
I clearly have some homework to do and some or all of the logic will need changes, but this gives me a generalized idea of what I'd like to make happen. From what I've read, knowing all this will make sketch writing somewhat easier or more streamlined. I hope you have literature in your own thread about the projects you built because I definitely want to read all that.
that is over 80 devices. On reflection, it may be advisable to consider the geography and use multiple Arduinos in a network reporting to a base station.
I also have 750 watt ATX (Dell ) that will be used for supplemental power draws. If by chance I am able to recreate a shield to have 7-10 interfaces, wouldn't this substantially decrease the amount of viewable devices? As you suspected in an earlier post, aside from the light times in hours, everything else is completely flexible for when the tasks need to be performed. At the moment, I am checking PH or EC every other day or so manually with a PH pen or EC pen. If the Arduino were to take a reading from each reservoir just twice per day, that would be a 200% increase, so there is more than enough time to go around as far as the code is concerned. I was hoping to bundle each kind of probe or sensor to a single shield or expansion board. So then it would look something like this;
...................................Relay for lights
...................................PWM for fans
...................................PH Shield for slaves
Mega - EtherShield/SD...EC Shield for slaves
....................................DO Shield for slaves
....................................CO2 Shield for slaves
....................................etc etc etc
Is this idea no longer practical or possible? I neglected to mention that my budget is almost non existent, so I have to cut every imaginable corner possible and first seek the cheapest route, well, the second cheapest as the cheapest would be to keep doing it all by hand, but you get the drift.
BTW, there were 2 image files in that zip, so I have a physical schematic as well as a component symbol schematic to start me off, thanks guys!
myggle:
Is this idea no longer practical or possible?
Probably both practical and possible, but only you can work it out. I only mention a network because there are so many devices, which implies a spacious operation and it could be simpler and cheaper to have a wireless network than pay for, and lay, all that cable.
I suggest you address the job in stages, using your own priorities.
Thanks Nick, I will give it a lot of thought and I got plenty of time. At the moment, the plan was to mount everything locally to the garden and Ethernet/POE back to the PC/internet. If wire costs prove too steep, Bluetooth is my next option.
The network I was alluding to is a collection of several Arduinos working together. This is something better done with wireless modules like the the NRF24. Bluetooth is better used to communicate with the non-Arduino world, like the reporting back to a PC.
Here is a benchtop 10 channel ph meter. I am hoping to find myself with something just like this and just to find that this exists after months of searching key words is reward enough for me right now. Hopefully I can find myself with something like this or learn how to build one myself.
) that will be used for supplemental power draws. If by chance I am able to recreate a shield to have 7-10 interfaces, wouldn't this substantially decrease the amount of viewable devices? As you suspected in an earlier post, aside from the light times in hours, everything else is completely flexible for when the tasks need to be performed. At the moment, I am checking PH or EC every other day or so manually with a PH pen or EC pen. If the Arduino were to take a reading from each reservoir just twice per day, that would be a 200% increase, so there is more than enough time to go around as far as the code is concerned. I was hoping to bundle each kind of probe or sensor to a single shield or expansion board. So then it would look something like this;