Problem when I use external SRAM in touchgfx. Wrong pixels.

[fernandogamax]

Hello.

I have made a custom project with STM32H735IGT. I use Touchgfx.

I am using external flash and external RAM. The problem is when I place the framebuffer in external RAM. Some green pixels appear as in image 1. When I place the framebuffer in internal RAM, the image is painted well.

I am using IS66WVH16M8DBLL-100B1LI RAM. I attached hardware configuration, the RAM is OCTOSPI2.

video of the problem and .ioc:

https://drive.google.com/drive/folders/1I96eqnh-5-xjDEKxfkxy-vVqeLvuVDY3?usp=sharing

Where is the problem?

[Msolinas]

mmm if you put the bitmap in the internal flash and you have the same effect, then it's useless to search on the octospi... without the external RAM everything is perfect, then it's the RAM. Very strange over some colors. I think only can be hardware line frequency problem or DMA data corruption.

[Msolinas]

please check if in cubemx every ram gpio pin is set to

GPIO_SPEED_FREQ_VERY_HIGH

[Msolinas]

You have PB8 LTDC_B6 and PB9 LTDC_B7 in fast mode disable in LTDC, why? this is blue region of color, exactly your problem

[fernandogamax]

I have checked GPIO_SPEED_FREQ_VERY_HIGH, all are fine.

PB8 LTDC_B6 and PB9 LTDC_B7 I have put them in fast mode, without any change

[Msolinas]

I think for hardware problem friend, everyting seems to be ok, try to change RAM chip.

[Msolinas]

Hi Fernando, do your RAM is on the same flash bus?

[fernandogamax]

No.

I have the flash on the octospi1, and the RAM on the octospi2. They are independent.

¿Could it be some RAM configuration parameter?

The evaluation board (STM32H735G-DK) mounts S70KL1281DABHI020, I am mounting IS66WVH16M8DBLL-100B1LI. I am setting the same configuration parameters. In the ST UM2679 it indicates that it is an alternative to S70KL1281DABHI020.

[Msolinas]

I don't think they are the parameters, as the problem is not random. You would have a homogeneous distribution across the entire display, whereas the drawing has a distribution on the color in particular. It's really a complicated thing. Are the octospi lines resistor finished? Are they the same length? can you post just the basic project? the .ioc you posted doesn't even have the octospi1 setting. which flash do you use? it's difficult to follow such detailed problems from a forum, can you take screenshots of the CAD with the detail of the tracks on the RAM?

[Msolinas]

Hi fernando, you do not set MPU, the MPU is very important for RAM settings.

[Msolinas]