Final year Computer Electronical Project - Getting the right Arduino for the job

Hi, this is my first post on this forum and I am very excited!

Before I get started, some background information about the project and myself: I am a final year student at NWU Pukke in South-Africa. I am working on a Hydroponic system for rural areas together with a controller system. I am planning on using a A-Frame like structure with the Ebb & Flow method for the hydroponics, a reservoir, fishpond pump and some PVC piping.

The main purpose of the project is to provide people in rural areas with fresh and healthy vegetables. This should be done by taking into account water and electricity supply. The A-Frame Hydroponics system will be implemented inside a 1,5m Width x 1,5m Height x 2m Length greenhouse, creating a controllable environment. This is where the fun part starts…

I am planning on using an Arduino together with temperature and humidity sensors such as the DHT11/21/22 (These works well with the Arduino apparently). The greenhouse will contain two fans used as actuators controlling the temperature inside the greenhouse. The budget for the project is R 2500. This is due to the fact that it is intended for a rural area.

I am not sure which Arduino device will be perfect for this project:

  • Inputs: 2 Sensors
  • Outputs: Some indicating LED’s and 2 fans

Some problems that still needs attention:
I doubt if two fans will be sufficient to control the temperature inside the greenhouse.
Power (Since it is in a rural area and my budget wont allow a solar pannel)

I will appreciate some comments or suggestions on a possible Arduino that will be able to be the brain of my project :slight_smile:

SPKloppers: I am not sure which Arduino device will be perfect for this project:

  • Inputs: 2 (DHT11/21/22) Sensors
  • Outputs: Some indicating LED's and 2 fans

Each humidity sensors will need one digital I/O pin. Each fan will need one digital output pin (a PWM output pin if they are low-voltage DC fans and you want speed control). Each LED will need one pin.

Any Arduino can easily handle the task. I would recommend the Arduino UNO which is the most common kind and easy to get help with.

To extend what @johnwasser has said, I suggest you use an Uno for developing the project and subsequently implement it on cheaper Arduinos with soldered connections for greater reliability.

You will also need to consider protecting the Arduino from excessive heat, humidity and insects. A hot moist greenhouse is not the best of environments for electronic equipment.

...R

Robin2: To extend what @johnwasser has said, I suggest you use an Uno for developing the project and subsequently implement it on cheaper Arduinos with soldered connections for greater reliability.

Specifically the "Pro Mini" which is missing the USB to serial converter, and thus much smaller (and cheaper). You can of course use it for prototyping and code development, in which case you need to connect a USB to serial converter. With pins soldered along the sides, it can be used in a "solderless breadboard" but without the pins, wires can then be soldered directly.

Robin2: You will also need to consider protecting the Arduino from excessive heat, humidity and insects. A hot moist greenhouse is not the best of environments for electronic equipment.

Heat: Keep it out of the sun. The MCU board itself will generate very little heat, but the power supply may generate some.

Humidity and insects - a sealed box; you can use a "conformal coating" on all non-moving parts (other than heatsinks).

You will need a driver circuit between the Arduino and the fans. What circuit you need will depend on the electrical characteristics of the fans you're using.

PeterH: You will need a driver circuit between the Arduino and the fans. What circuit you need will depend on the electrical characteristics of the fans you're using.

Thank you very much for the feedback Peter. I will need some sort of Driver circuit yes, to "drive" the fans due to voltage differences between the Arduino and fans? Arduino wont' be able to output 12V required by the fans for example right?

I am still looking into which fans I will be using, my main concern is, fans alone won't really lower the temperature inside the greenhouse. My budget however won't allow any other fancier methods though. Manual air vent and controlled fans are what I have at the moment.

Thank you Paul, Robin and John for feedback on the Arduino that I can use for this project.

I'm going to develop the project on an UNO board, such as the UNO R3 for example and then suggest in my final documentation that a much smaller (cheaper) board such as the "Pro Mini" will be ideal for future productions of the prototype.

I appreciate the feedback from you guys!

Regards SP Kloppers

since you have a greenhouse, you can open windows and let out the heat. one way is to use a pipe and floats.

if you have a large pipe that is 1/2 meter tall, an outlet on the bottom and an open top to allow it to fill. put one under each window. in the pipe you have a smaller pipe that will float and be connected to the window. when the pipe is filled, the float rises and the window opens. the power comes from the pump. to close the window, drain the water.

a relay is the best way to connect to higher voltages.

once you have the final circuit laid out with the inputs and outputs, you can have a board made. once you are certain of the input and output requirements, analog sensors or digital ones, how many outputs, etc, you can downsize your needs to use a chip that will work such as the ATTINY84 . a 14 pin chip with enough pins to monitor a couple sensors and control a couple pumps and fans. your board would have all the parts needed and be pretty low cost.

your electronics side, micro, relays, sensors, etc should be less than R 250 ($25 USD)

here in the US, I see solar pumps that will take water at ground level and raise it a foot or so. very small head pressure. but they cost around $150USD. with a battery backup that will run for a few hours. typically around 200 Gallons per hour. should be enough for moving water in a hydroponics greenhouse.