Which arduino board should I base this project off?

Hello all,

I'm looking to build a hydroponics controller/monitor. I've seen quite a few projects out there that are multiple years old. I've seen many new arduino boards come available since then.

Because of this, I'd like to purchase a few things and get started. However, I don't want to purchase an arduino UNO for example, if the mega is the board I will need for a project such as this.

I'd like to perform these functions:
-Monitor PH
-Monitor TDS/EC
-Monitor water temp
-Monitor water resevoir level
-Actuate a water pump based on a timer
-Turn a light on/off based on another timer
-log this data over time
-Display this data on a 3-7" touch screen

-PH/TDS/TEMP/resevoir sensors will be remote from the controller/display unit and will all reside in the water resevoir. I would prefer these sensors be wired to the controller(so one central power source), but they could be wireless if it's easier/better to do so.

I'm familiar with picking out that i'll need at least a 4 channel relay, sonar sensor, ph/tds probes etc. However, i don't know if an arduino UNO (or YUN) or mega is what I should use as the base(or something entirely different).

Would someone be willing to assist me there?

The real determinant is how many pins you need. Work out how many analog inputs, PWM outputs, general i/o, serial and other communications. If any one of those numbers exceeds the capability of the Uno, then buy the Mega.

Some things require fixed pins. An SD card for data logging will use the SPI pins. The LCD may share those pins if it is an SPI device. But an I2C sensor will use the I2C pins instead.

Probably a Mega. The touch screen probably determines this but, even without it, the Mega is usually the way to go with datalogging projects, as you are likely to run out of memory with a Uno sooner or later as the project inevitably grows.

Can you post links to pH and EC sensors? These sensors could be bare probes with some sensing circuit or all-in-one sensor with integrated sensing circuit. Arduino won't be able to connect to bare probes.

Because of the variety of sensors available, you need to be careful when choosing them, you have to make sure their output will match the controller.

So I'd be researching sensors, comparing the available inputs of the arduino controllers.
Such as SPI, I2C, analog, UART and even parallel.

Tom.... :slight_smile:

Really impressed with the responses everyone. Thank you very much.

The probes are bare probes with BNC connectors for PH/TDS. I was planning on utilizing atlas scientific's arduino interface boards for them(forget what the official name is off the top of my head).

As for the rest of the sensors, thank you for pointing out the different interface styles. I'll be sure to focus on that.

If memory could be a concern. Would it be better to integrate a raspberry pi for interface/touchscreen logging? Or would I be greatly complicating things?

The inspiration from this project came from here as a reference. Pretty impressed. I really like the fact that remote sensors are utilizing CAT5 cable for power from the main controller board.

If memory could be a concern. Would it be better to integrate a raspberry pi for interface/touchscreen logging? Or would I be greatly complicating things?

What you describe seems to be pretty normal for a Mega datalogger, so you probably would be.

OK, great. I'll grab a mega and start learning. Thank you all for the responses!