Issues with LTDC and Audio Configuration on STM32 - Conflict Between Display and FATFS/Audio Playback (STM32F469i-DISCO

[DerFreaker]

Hi everyone,

I'm encountering a problem with my STM32 project where I need to use both LTDC for display and audio playback (via FATFS). The issue seems to stem from a conflict in clock configurations.

My setup: 

    MCU = STM32F469i-Disco

The problem

When I configure the clock for LTDC like this:

LTDC clock configuration (stm32469i_discovery_lcd.c line 342):

 

 

 

PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_LTDC;
PeriphClkInitStruct.PLLSAI.PLLSAIN = 384;
PeriphClkInitStruct.PLLSAI.PLLSAIR = 7;
PeriphClkInitStruct.PLLSAIDivR = RCC_PLLSAIDIVR_2;
HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);

 

 

 

The display works perfectly, but the audio playback through FATFS fails (specifically in Audioplayer.c at line 42).

However, when I comment out the LTDC clock configuration:

// PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_LTDC;

The audio playback works again, but the display shows an artifact—a black line appears on the screen (as shown in the attached image).

 

LTDC Timing Configuration:
Timing Configuration:

 

hltdc_eval.Init.HorizontalSync = (HSA - 1);
hltdc_eval.Init.AccumulatedHBP = (HSA + HBP - 1);
hltdc_eval.Init.AccumulatedActiveW = (lcd_x_size + HSA + HBP - 1);
hltdc_eval.Init.TotalWidth = (lcd_x_size + HSA + HBP + HFP - 1);

Initialize the LCD pixel width and pixel height:

hltdc_eval.LayerCfg->ImageWidth = lcd_x_size;
hltdc_eval.LayerCfg->ImageHeight = lcd_y_size;

 

My question:

How can I resolve this conflict so that both the LTDC display and audio playback work simultaneously without any artifacts or errors? Is there something wrong with my clock configuration, or is there a better way to manage the clocks for these peripherals?

Any insights or suggestions would be greatly appreciated!

Thanks in advance for your help.

[Andrew Neil]

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@DerFreaker wrote:

MCU = STM32F469i-Disco

---

That's the board - not the MCU.

The MCU is the STM32F469NI chip which is mounted on that board.

 

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@DerFreaker wrote:

The issue seems to stem from a conflict in clock configurations

---

Seems a reasonable hypothesis - so test that hypothesis.

http://www.8052mcu.com/faqs/120313

Compare & contrast the working & not-working configurations.

 

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@DerFreaker wrote:

audio playback through FATFS fails (specifically in Audioplayer.c at line 42)

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What is that line? What, exactly, goes wrong there?

 

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@DerFreaker wrote:

when I comment out the LTDC clock configuration:

// PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_LTDC;

The audio playback works again, but the display shows an artifact—a black line appears on the screen (as shown in the attached image).

---

Have you looked at the display interface lines with a logic analyser or scope to see what's happening?

[Andrew Neil]

---

@DerFreaker wrote:

on line 42 on the f_lseek function it gives me the fatfs error "FR_DISK_ERR".

---

So step into that function to see exactly what fails, and where.

Again, have you looked at the interface lines with a logic analyser or scope to see what's happening?

 

 

[DerFreaker]

So Ive stepped into the function and saw that the main problem is happening in usbh_msc.c at line 785.

MSC

 

 if ((phost->device.is_connected == 0U) ||
 (phost->gState != HOST_CLASS) ||
 (MSC_Handle->unit[lun].state != MSC_IDLE))
 {
 return USBH_FAIL;
 }

 

 MSC_Handle->unit[lun].state is for whatever reasons on MSC_READ...

i dont know how to fix it by now.

@Andrew Neil @wrote:

Again, have you looked at the interface lines with a logic analyser or scope to see what's happening?

 

 

No, unfortunately I don't have a logic analyser.