Brian Rogers

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10 years, 7 months ago.  This question has been closed. Reason: I found the answer to the question myself after some more intensive research.

Banding on 2.4" display

I have been trying to get this display up and running but am just getting banding across it. It looks to be bands of 8 bits full of garbage interlaced with bands of 8 bits that are set up correctly. I am using the TFTLCD_8bit library to drive this and as you can see from the text, it seems to be configured correctly. Any ideas? It is using the ILI9325 driver chip in 8 bit mode and that all seems to be correct too!!!

Code from main.cpp: /* print something on the screen */ lcd.Print( "Testing 8 bit mode", CENTER, 54); /* align text to center horizontally and use starndard colors */ lcd.FillCircle(160, 120, 15);

/media/uploads/BrianRogers/20140427_182027.jpg

2 Answers

Frank Vannieuwkerke
10 years, 7 months ago.

Can you provide more info:

  • Display, display board origin (datasheet)?
  • When does the banding appear, eg : before you write text/graphics to the display?

I once worked on a ILI9327 based LCD and discovered there are also 'compatible' chips where the init routine has to be modified slightly to get it working properly.

It's a cheap display from China that they sent me (eventually) a datasheet for that states it is a Displaysun device, MODEL NO: DST2401PH using as previously stated, an ILI9325 driver chip.

After a bit more research I found it actually uses an LGDP4532 driver and armed with that I found that one of the internal registers (0x90) was being given the wrong value. A quick alteration and it is now working correctly.

posted by Brian Rogers 28 Apr 2014
ceri clatworthy
10 years, 7 months ago.

A quick thought:

are you sending 8 bits of data, when the screen is expecting 16 bits.

What happens when you attempt to write to the 'garbage-ed' area ?

can you repeat with this ?

    lcd.Print( "Testing 8 bit mode", CENTER, 54);
    lcd.Print( "Testing 8 bit mode", CENTER, 64);
    lcd.Print( "Testing 8 bit mode", CENTER, 74);

also check all your connections etc,

90% chance it is a line that is hi/lo/floating incorrectly.

Ceri

The device can run in 8 or 16 bit mode. As each bit is accessed independently then if it was an addressing issue it would be either all or none that would work. It's looking more and more like a hardware issue with the LCD drivers. As for trying the text in different places, I have tried this and it just moves to where you expect it to be behind the banded areas but the visible bits always still look ok.

posted by Brian Rogers 28 Apr 2014