[DIY] Arduino UNO project for feeding plants

This is the schema: http://i.imgur.com/dfH33NF.jpg of the project which I've found and want to build. In this project both RTC and LCD uses the same analog pins A4 & A5. As I read this is because both these devices uses I2C bus. I found this information on google however I couldnt find it on the devices, how can I know whether ther is I2C support or not.

The difference from the above project is that I have this LCD: Touch Screen Shield for Arduino UNO – misc.ws

Morover I have RTC, Arduino Uno.

Q1) First thing which I dont understand was when I started sample Adafruit_Gfx paint example with TouchScreen library usage. Code defines the same pins A1 and A2 for the LCD and touch layer - these are two different devices one could say. Does it mean that it uses I2C bus?

Q2) And more important question is will I be able to connect RTC which uses two analog pins RTC DS3231 + 24C32 I2C and to which PINs? If A0-A4 will be taken by LCD and TouchScreen, A5 is free, can I connect RTC to A4 and A5 or A3 and A4 ?

#define YP A1 // must be an analog pin, use "An" notation!
#define XM A2  // must be an analog pin, use "An" notation!
#define YM 7   // can be a digital pin  (9 uno)(pin 23 Mega)
#define XP 6   // can be a digital pin  (8 uno)(pin 22 Mega)

#define TS_MINX 150
#define TS_MINY 120
#define TS_MAXX 920
#define TS_MAXY 940

// For better pressure precision, we need to know the resistance
// between X+ and X- Use any multimeter to read it
// For the one we're using, its 300 ohms across the X plate
TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300);

#define LCD_CS A3
#define LCD_CD A2
#define LCD_WR A1
#define LCD_RD A0
// optional
 #define LCD_RESET A4

The I2C bus is multiplexed with analog input 4 and 5 so whenever you use any I2C device, you won't be able to use analog input on 4 or 5.
You can connect a number of devices to I2C bus so no problem connecting 2 devices. Your LCD touch screen is not likely an I2C device. It just uses 2 analog input pins for touch. The example code also uses other analog pins as digital pins, for convenience in wiring since it is already using analog input pins. All wires go to the same location. You will need to wire these 4 pins on digital pins so that a4 and a5 are fee to connect your I2C clock and eeprom, also a0 and a1 free to hook up touch.

Unfortunatelly I need 3 digital pins for 3 engines -> here is the link of the project but with CrystalLCD not TFTTouch one http://i.imgur.com/dfH33NF.jpg. Currently pins 2-9 are taken by LCD. Free are 0,1, 10,11,12,13, so engines will take 11,12,13, I would have 0,1,10 pins free..

Could I wire LCD_RESET to digital pin without changing the tftPaint demo project (apart from this line defining LCD_RESET)? LCD_RESET is commented to be optional so maybe there is even one more solution?

Ahh! yes it worked !!! I connected LCD_RESET to digital 10 pin and defined LCD_RESET = 10. Everything seems to work or I did something wrong ?

Seems right. As long as you don’t use one pin for two different things, you are ok. So your LCD uses 8 pins, 2 to 9?
Your sample code didn’t say you needed that many. I don’t have it myself though.