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February 7, 2025
Question

How stm32f429 disco uses ltdc if the mode isnt set correctly

  • February 7, 2025
  • 1 reply
  • 828 views

Hi 

I'm trying to understand something in the schematic the disco1 IM pins are set to  4-wire 8-bit serial I

bbas121_0-1738944204951.png

In the picture below they are connected using the SB22-25 but I've checked the board and they are not soldered so it is not possible to set the manually

bbas121_1-1738944297852.png

I cheked the ili9341 datasheet and you cant change the mode using register 

But there a lot of examples that this baord using ltdc with the display with paralel rgb565 how is this possible if the mode is not set correctly 

 

1 reply

Tesla DeLorean
Guru
February 7, 2025

The combination of pull-up/down resistor placement, as inferred on the diagram as IM[0..3] = 0110, provides a static state setting the screen can use at startup. It's probably possible to reconfigure the controller via the internal registers later.

You'd need to make the SB to allow the MCU to change the setting via there pins, but then it would need to be correct.

Probably to permit different displays to be accommodated.

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