[sdiy] LCD hot rodding

rburnett at richieburnett.co.uk rburnett at richieburnett.co.uk
Mon Apr 8 15:25:39 CEST 2024


Both of these issues (top line only on the OLED display, and black 
blocks only on the LCD) sound like initialisation issues with the 
display controller IC.

In each case did you have the new display connected at the time when the 
kit was powered up?  Or only connected the display after power up?  It 
needs to be connected at boot-up to receive commands and get properly 
initialised for the right number of rows & columns, etc.

Failing that it sounds like the replacement displays aren't entirely 
compatible with the Hitachi 44780 initialisation sequence of the 
original display.  I've had problems with this before when substituting 
displays in various bits of kit.  Sometimes the firmware doesn't wait 
long enough between commands, or it doesn't follow the exact recommended 
command sequence but still manages to work with some screens (>.<)

-Richie,



On 2024-04-08 13:56, mark verbos via Synth-diy wrote:
> I added a trim and it only lightened or darkened the black boxes.
> 
> 
> 
> Mark
> 
> 
> 
> 
>> On Apr 8, 2024, at 2:51 PM, Flügel, Werner <werner.fluegel at b-tu.de> 
>> wrote:
>> 
>> Am 08.04.2024 um 14:38 schrieb mark verbos via Synth-diy:
>> 
>>> Second, I plugged in the LED backlighted one today. The backlighting 
>>> looks great, but I only get solid black boxes all the way across the 
>>> screen.
>>> Does anyone know about these things? What am I doing wrong here?
>> 
>> Is there a trimmer for contrast? I had a similar effect building the 
>> Ambika Polysynth, adjusting the contrast helped in my case.
>> 
>> --
>> mfG.
>> 
>> W.Flügel
>> 
>> Wir sind IT. Das ist kein Beruf, das ist eine Diagnose.
>> <7123838.uCcSxbalbl at rotfl.franken.de>
>> 
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