chipKIT® Development Platform

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MX7 and I2C LCD

Created Tue, 12 Sep 2017 12:13:20 +0000 by aabfm


Tue, 12 Sep 2017 12:13:20 +0000

Hi everyone, Here is another bit I have been looking around for some clue but everything is down to Arduino only. I bought on eBay one of those very common 20x4 LCD displays already with an I2C converter at the back. Simple question: does anyone know how to make this display to work on a MX7 platform? or where can I get information on how to make it work? All the sketch examples on UECIDE point to Arduino but not to MX7. As a quick note I've already tested it with a standard Arduino Uno and it works perfectly. Thanks in advance.


Tue, 12 Sep 2017 13:37:36 +0000

I've just downloaded a LiquidCrystal_I2C library which requires the wire.h library. Is it possible to use it directly with the MX7? If so how can I define which of the I2C ports to use? Thks


Tue, 12 Sep 2017 17:48:02 +0000

After trying the library, although the LCD display worked as expected I had this message back from UECIDE:

• Error at line 1145 in file cpudefs.h: ‣ "OPT_BOARD_INTERNAL" redefined [enabled by default]


Wed, 13 Sep 2017 11:52:13 +0000

It's just a warning and can be ignored. It's because UECIDE defines that symbol as default and the chipKIT core redefines it. It's not actually a problem, just noise.


Wed, 13 Sep 2017 15:20:23 +0000

Hi, Actually I've 'solved' it by commenting line 1145 with the "#define" statement as shown below:

//Fix issue 213
#ifndef __PIC32_PPS__

No more warnings. BTW the cpudefs.h is located at:



Wed, 27 Sep 2017 11:51:40 +0000

If you want the location in Windows it will be