I have a 2.2 color serial display I with plans to use on and existing Arduino sketch that requires an I2C interface. I've tried every way under the sun to get this one do display something in I2C and it doesn't happen. I've tried all the samples in Digole's Arduino section and the compatible ones work fine in everything but I2C, I've tried the 10K pull down resistors on the SCL and SDA. I've upgrade the firmware from 3.9 to 4.3, I've verified the address really is 0x27. I've also tried several version of Arduino from 1.06, 1.6.7, 1.8.1 and 1.8.5 I'm not a a programmer so that complicates things even more, but it acts like the samples are not compiling in I2C. I've tried commenting out all the UART and SPI and leaving just the I2C and they won't compile. Keep getting the same mydisplay error. If anyone can tell me a sample program that will run in I2C or what initiating instructions I need to get this thing to display anything in I2C it would be greatly appreciated. Then how to change the address to 0x24. I've seen the command it takes to do that, but I don't know how to put it in a sketch to initiate I'm hoping once if find what it takes to get this thing working, I can then figure out how to change the existing sketch to work with this one. If anyone has happened to use one of these modules on the Arduino UNO running RoastLogger and RoastLoggerTC-4, that's where I plan to use this one and replace the 2004 LCD display I'm currently using.

Then, it should work.

The problem might be on the sketch or Arduino hardware, did you use:

#define _Digole_Serial_I2C_

instead of 

#define _Digole_Serial_UART_

Yes the three samples that work perfect in the UART mode have that exact ifdefine statement for I2C. If I try to comment out the UART defines and force it to read only the I2C then they error out where they say mydisplay is not named, but it's in the I2C just like it is in the UART. I'm just trying for find anything that will show in I2C so I can see what's needed to initiate it. Even a simple Hello. If I do nothing to the sketch and compile them just the way they are, the compile with no errors. After compiling them and run them in UART mode the work perfect. When I put the jumpers in the I2C mode, the still compile and load just fine, but the display never comes off the Digole 's in it. Make no attempt, not even a flicker that there was an I2C sketch running. In the UART more, when they finish running, I can unplug the Arduino and plug it back in,, that the Sample sketch runs again. I unplug and plug it back in I2C and I just get the Digole logo. I've tried three different Arduino UNO's, since I about a 1/2 dozen of them. I use them in several projects.

 You need to change:
"
#define _Digole_Serial_UART_  //To tell compiler compile the special communication only, 

//all available are:_Digole_Serial_UART_, _Digole_Serial_I2C_ and _Digole_Serial_SPI_

#include <DigoleSerial.h>

"
to

"
#define _Digole_Serial_I2C_  //To tell compiler compile the special communication only, 

//all available are:_Digole_Serial_UART_, _Digole_Serial_I2C_ and _Digole_Serial_SPI_

#include <DigoleSerial.h>

"

I've done that several times but I've been leaving the line the Defines mydisplay, and the \27. do I need to comment out that line of code? I will try it all again, but it will take a few minutes.

HotDam! Thank you It finally displayed something besides your logo. It went through the whole sample in I2C. I was commenting out that line and changing it in the one below that one

Now, while I've got you, can you give me the code string I can just insert into this sample to change permanently the address to 0x24. That's the fixed address in the code I want to use it in.

 You need work at old address (0x27) first, after comminucation established, use change I2C address command:

mydisp.setI2CAddress(0x24);

Then you will see a notification on the display to tell you the address changed to 0x24.

Then on the sketch, change:

DigoleSerialDisp mydisp(&Wire,'\x27');

to 

I will dance at your wedding, or next wedding! Thank you so much, that looks simple enough that even I should be able to do that. I'm playing with the other samples that work now to get them to run in I2C. Then the fun begins, trying to figure out how to change my coffee roasting sketch to work on this display. I'm trying to make me a small controller and need the small display to do it. Again, luv your support, thanks.

Address change done! Works like a champ. Thank you!!!!

OK, got it down to 6 lines and it works. I posted them but it runs them all together and hard to read so erased them