[En-Nut-Discussion] nutdevice devLcd not working properly

Sam Van Den Berge sam.van.den.berge at telenet.be
Tue Feb 26 18:46:32 CET 2013



I've recently picked up my old code build with ethernut 4.8.7. Back then I
made a simple test program to write some text to my LCD:
NutRegisterDevice(&devLcd, 0,0), freopen, printf(ESC_CLRHOME) and a line
printf("Hello"). After that I've put an endless loop with NutSleep in it.

That program worked like a charm. I saved the hex-file and today I flashed
that hex-file into my device ( atmega128, ethernut v2.1 rev. B. ). It still
worked and I could see the text on the LCD.

Now I downloaded the most recent ethernut version (5.1.0), recompiled my
project but nothing happened. The screen does get initialized by calling
NutRegisterDevice(..). I know that because the black squares on the display
disappear. Unfortunately, my text doesn't come on the display anymore. The
LCD remains blank. 

I've downloaded a random HD44780 library and made a test program without
Nut/OS. That program works perfectly. 

Now by first getting some text on the display using the third party lib, and
then immediately afterwards programming the board again with the Nut/OS
version of controlling the display, I was able to get some weird text on the

I've found a pattern, namely, it looks like the high and low nibble of every
character gets switched. For example, if I write "7777777" (7 = 0x37 ) to
the display, I get "ssssss_" (s = 0x73 ) on the LCD. So does W (=0x57 ) gets
translated in u (=0x75). 

As a reaction, I tried to rebuild ethernut and instead of using the mask
0xF0 for the data port ( LCD in 4-bit mode ), I now tried to use the mask
0x0F. But that is even worse. Now I couldn't find any relation with my
original text. 

Is there anyone who could confirm that the LCD HD44780 driver in 4-bit mode
is still working properly? Or someone who might have an idea where to look

I tried rebuilding ethernut 4.8.7 but I get errors about methods that are
deprecated. I have also checked HD44780.c and found out that the methods inp
and outp are replaced by inb and outb in the method LcdSendNibble.  


Thanks in advance. 



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