LCD2004 and Arduino mega 2560

Other Hardware Displays
23

they are soldered.

24

All things considered I am wondering if you might have a faulty display module. I have only had one fail and while the LED Power diode glows the display is totally dark. Anyway, you have done your due diligence and after all said and done my best guess is a failed board. :frowning:

Ron

25

Sorry to have to say, but I concur. This should be quite a straightforward exercise.

If you have or know someone with the tools and soldering skills then it might be possible to remove the back board and run the display without it - just needs more wires - or replace only the back board. Otherwise I guess you will need to buy a new display.

26

Post the diagnostic output of running the I2CexpDiag sketch that is included in the hd44780_I2Cexp io class.

That will provide additional information to help us diagnose any potential issues.

It tests the I2c connections, auto locates the i2c address, attempts to initialize the LCD and then does a memory test of the LCD DDRAM and CGRAM.

bill

27

Hi everyone, thanks for helping me to solve this problem and sorry for my broken English
Here is the update,
I have bougth an arduino UNO to test if the code, hardware or a software problems,
but all same thing works on UNO but not arduino mega 2560.

567742720_1997560224368640_591308772995791871_n
567742720_1997560224368640_591308772995791871_n1536×2048 191 KB

28

Works fine with a Mega 2560 here. What conclusions can we draw from that?

lcd2004 and mega
lcd2004 and mega1024×768 210 KB

29

Well I am glad it works. Strange as that same code works on my Arduino Mega and my Arduino Uno REV. 3 but anyway, it works. :slight_smile:

Ron

30

Possible explanations:

  • was miswired on Mega, fixed when wired to Uno - try on Mega again, to be sure
  • poor jumpers - Duponts are horrible - inspect carefully, replace all for test
  • poor solder joint on Mega - inspect carefully, resolder if there's any doubt
  • blown pin on Mega - test pins by driving a LED/resistor pair using each pin (SDA, SCL).

When testing pin, If LED can be lit when wired to GND, and lit when wired to VCC, pin is good. Don't forget the resistor, in either configuration.