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Null Packet Size is not visible in CubeMX Gui

Associate II


I think I found a small bug.

I copied the settings from one project to another. After that I did a diff to show if I'm missed to change some value. And one variable was missing, so I checked double to find the variable in the GUI, but I did not found it. Till I found the bug described below.

When Video Mode is "Non Burst Mode", it has an additional variable "Null Packet Size", when this variable is changed it is in the IOC file. Till now everything correct, but if now the Video mode is changed to "Burst Mode" then the variable is not anymore visible in the GUI, but still available in the .ioc file. In my opinion the the variable "NullPacketSize" should be removed from the .ioc file when it is not visible in the GUI. (See also pictures)


Thanks in advance





Mahmoud Ben Romdhane
ST Employee

Hello @nobody ,


First let me thank you for posting and welcome to the ST Community.

For more investigation I suggest that you provide your ioc.File.







Good morning,

As requested I added the .ioc file. The ioc file is from the example DSI_ULPM_DataClock (STMicroelectronics/STM32CubeU5: Full Firmware Package for the STM32U5 series: HAL+LL drivers, CMSIS, BSP, MW, plus a set of Projects (examples and demos) running on all boards provided by ST (Nucleo, Evaluation and Discovery Kits). (

I did following steps:

  1. opened the .ioc
  2. change the "Video Mode" to "Non Burst Mode with Sync"
  3. added some "null Packet size"
  4. saved
  5. change back the "Video Mode" to "Burst Mode"
  6. saved
  7. checked the .ioc file with the notepad++ (see printscreen), where the "null Packet size" variable is still available


Thanks in advance


Hello @nobody ,

After investigation, I can confirm that this behavior does not affect the functionality of this peripheral.

Even the video mode is set to Burst Mode, you can find that the generated code includes this instruction.

[ VidCfg.NullPacketSize = 0; ] in main.c.