LTDC not generating clock

[PhilipC]

Hi,

I have a Nucleo-U5A5ZJ-Q board which i replace the mcu with a STM32U5A9ZJT6.

I'm trying to use LTDC to control a 800x480 LCD (WF50FTYAGDNN0#) via RGB888.

Eventually running touchgfx, but I have fallen over at the first hurdle.

I have read many tutorials and forum posts and no one seems to have the same issue as me.

I started a blank project and followed this

https://support.touchgfx.com/docs/development/board-bring-up/how-to/03-display-internal

But my display remains a black screen, I then probed PD3 (LTDC_CLK) where I expected the 25Mhz clock signal that was configured, but saw nothing. 

I also tried switching the pins "Max output speed" to Very High as I saw somewhere that this was required.

I then switched PD3 to GPIO_Output and toggled it to make sure connections are correct.

Is there something wrong with my clock setup? I tried a test of toggling a pin in the while loop with a 1ms delay and the scope says a full cycle took 4ms instead of the expected 2ms... but then I set the delay to 10ms and eveything is as expected on the scope.

Note about the display: it doesn't have Hsync and Vsync lines I assume this means it is permanently in DE mode and I can leave those pins floating from the mcu?

Any help would really be appreciated as I have been going at this for a couple of days now.

[PhilipC]

Ah sorry I flipped to PLL3 when experimenting stuff, the code does now also point to PLL3.

Does this look like the PLL3 registers aren't reflecting what the code says?

void HAL_LTDC_MspInit(LTDC_HandleTypeDef* hltdc)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
  if(hltdc->Instance==LTDC)
  {
  /* USER CODE BEGIN LTDC_MspInit 0 */

  /* USER CODE END LTDC_MspInit 0 */

  /** Initializes the peripherals clock
  */
    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_LTDC;
    PeriphClkInit.LtdcClockSelection = RCC_LTDCCLKSOURCE_PLL3;
    PeriphClkInit.PLL3.PLL3Source = RCC_PLLSOURCE_HSE;
    PeriphClkInit.PLL3.PLL3M = 1;
    PeriphClkInit.PLL3.PLL3N = 15;
    PeriphClkInit.PLL3.PLL3P = 2;
    PeriphClkInit.PLL3.PLL3Q = 2;
    PeriphClkInit.PLL3.PLL3R = 10;
    PeriphClkInit.PLL3.PLL3RGE = RCC_PLLVCIRANGE_1;
    PeriphClkInit.PLL3.PLL3FRACN = 3072;
    PeriphClkInit.PLL3.PLL3ClockOut = RCC_PLL3_DIVR;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
    {
      Error_Handler();
    }

    /* Peripheral clock enable */
    __HAL_RCC_LTDC_CLK_ENABLE();

    __HAL_RCC_GPIOE_CLK_ENABLE();
    __HAL_RCC_GPIOF_CLK_ENABLE();
    __HAL_RCC_GPIOD_CLK_ENABLE();
    /**LTDC GPIO Configuration
    PE2     ------> LTDC_R0
    PE3     ------> LTDC_R1
    PE4     ------> LTDC_B0
    PE5     ------> LTDC_G0
    PE6     ------> LTDC_G1
    PF13     ------> LTDC_B1
    PE7     ------> LTDC_B6
    PE8     ------> LTDC_B7
    PE9     ------> LTDC_G2
    PE10     ------> LTDC_G3
    PE11     ------> LTDC_G4
    PE12     ------> LTDC_G5
    PE13     ------> LTDC_G6
    PE14     ------> LTDC_G7
    PE15     ------> LTDC_R2
    PD8     ------> LTDC_R3
    PD9     ------> LTDC_R4
    PD10     ------> LTDC_R5
    PD11     ------> LTDC_R6
    PD12     ------> LTDC_R7
    PD14     ------> LTDC_B2
    PD15     ------> LTDC_B3
    PD0     ------> LTDC_B4
    PD1     ------> LTDC_B5
    PD3     ------> LTDC_CLK
    PD6     ------> LTDC_DE
    PE0     ------> LTDC_HSYNC
    PE1     ------> LTDC_VSYNC
    */
    GPIO_InitStruct.Pin = GPIO_PIN_2|GPIO_PIN_3|GPIO_PIN_4|GPIO_PIN_5
                          |GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_8|GPIO_PIN_9
                          |GPIO_PIN_10|GPIO_PIN_11|GPIO_PIN_12|GPIO_PIN_13
                          |GPIO_PIN_14|GPIO_PIN_15|GPIO_PIN_0|GPIO_PIN_1;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF8_LTDC;
    HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = GPIO_PIN_13;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF8_LTDC;
    HAL_GPIO_Init(GPIOF, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9|GPIO_PIN_10|GPIO_PIN_11
                          |GPIO_PIN_12|GPIO_PIN_14|GPIO_PIN_15|GPIO_PIN_0
                          |GPIO_PIN_1|GPIO_PIN_3|GPIO_PIN_6;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF8_LTDC;
    HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

    /* LTDC interrupt Init */
    HAL_NVIC_SetPriority(LTDC_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(LTDC_IRQn);
    HAL_NVIC_SetPriority(LTDC_ER_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(LTDC_ER_IRQn);
  /* USER CODE BEGIN LTDC_MspInit 1 */

  /* USER CODE END LTDC_MspInit 1 */
  }

}

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[PhilipC]

I just tried SAI2 peripheral as it is also on APB2, and it can write to its config registers fine.
I can also write to them and read them fine, so something specific to LTDC.
All the documentation I can find just points to LTDCEN being enabled before writing and nothing else, I'm really at a loss here.

SAI2->GCR = 1;

[Tesla DeLorean · Accepted solution]

@STOne-32 is it possible this could have been fused like the U5A5 with the LTDC disabled? All peripheral registers are presenting as stuck-at-zero

@PhilipC can you provide a clear picture of the top markings of the IC you mounted.

[PhilipC]

So I went to take a photo and couldn't believe my eyes...
I must have got the chips swapped at somepoint after removing the A5.

I have now swapped the A9 on and sure enough getting all the registers and a LTDC_CLK.
Thank you for your input and sorry for the confusion.

 

The display is now cycling through Black, White, Red, Green, Blue even though I have an empty while(1) but atleast it's a new problem.

I feel like a *** bashing my head against a wall for the past week only to find out I took the A5 off and put it back on... Thank you for you time @Tesla DeLorean 

[STOne-32]

Dear @PhilipC ,

Great !  And yes , it happens to all of us :) . 

@Tesla DeLorean  Merci ! 

Ciao,

STOne-32