Wich Arduino to pick with this setting?

Hey,

i'm new to the scene of microcontrollers, i thought of using RasPi for my project, but lastly i think one Arduino would be the best choice.

So, i will be using the following components in my project, and i don't know if the Arduino Uno will be enough, and if that's true, should i pick the Mega?

The modules in italic are for future versions of my project. But have to keep on mind that i will need space/pins for those.

The Easy Driver with one stepper
One i2c (dedicated IIC bus control) and to it connected one LCD AMC2004A?
Temperature sensor (DS18B20)
One i2c interface for pH measuring (here)
One SSR relay module board (here)
One Ultrasonic module sensor (HC-SR04)
One humidity&Temperature sensor (DHT11)
2 Led as indicators
One or two buttons

Thank you for your clarifications, hope you can help me out here!
Cheers, Sousa.

The Arduino Uno is the easiest to use Arduino board.

And it can do easily those task.
The real advantage of Arduino are the libraries.

There is a library for that display, for I2C and for that temperature sensors.
I did not check the PH sensor, and I did not check how many pins the Easy Driver needs.

http://playground.arduino.cc/Learning/OneWire

You have to write down how many pins are needed.
The display is able to use 4 datapins instead of 8, or you can use an I2C converter or shift register to reduce the number of pins.

I think the Easy Driver uses only the direction and a stepper pin. If it doesn't use anymore, you could use the LCD in 4-bit mode and have some spare pins to be used for buttons and so.

You can always upgrade to the Arduino Mega 2560.
It is very compatible with the Uno, so most of the times the upgrade is changing the used pins in the sketch.
http://arduino.cc/en/Main/arduinoBoardMega2560

Hi Erdin, thank you for your reply.

So, it resumes to the number of pins i'm about to use? I don't think my program will have more than 32k, but this is a Uno limitation right?

Check my first post, you will see i added more sensors, as those are optional and in my first stage i will try to set up things properly for the main sensors, but eventually i will add more. Would the Uno still be enough?

What's the drawback of picking right now the Mega? Only the price? Is it harder to work with?

Okay, okay, I get the idea.
That list will only get larger, once you start having fun with the sensors.
You should buy the Mega 2560 ! Perhaps with a Mega compatible proto-board shield.

The Mega 2560 is bigger and more expensive.
And not all (older) shields fit on it, for example the I2C pins are at other pins.
The Mega can have trouble sometimes with uploading a sketch. If you encounter that, you could write a new bootloader in the Mega.
Arduino 1.0.4 and 1.5.2 have improvements for the Mega bootloader.

You could perhaps also buy a cheap Uno clone, to test a single sensor. Take into account that you could blow an Arduino, for example if you have a wire of 12V touching a pin.
An Arduino board can be used as ISP programmer, you could use the second board to write the new bootloader in the Mega.

I've chosen to use Arduino Uno, based on what you've said. I will get used to it and will try to implement 1 or 2 sensors, together with the LCD screen i have.

Let's see if everything goes well. I'll certainly post the project here, i think it's quite fun and probably some help becomes handy.

Cheers Erdin and thank you once again.
Sousa