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Associate
October 20, 2025
Solved

STM32WB5 transparent mode issue

  • October 20, 2025
  • 2 replies
  • 278 views

Hello everyone,

 

I am strugling with a STM32WB5MMGH that I am using with transparent mode.

 

I am using the STM32WB5MMGH on a custom board with a STM32L4R9VIT6. The goal of the project is to use the STM32WB5 as a bridge to send data from a smartphone app to the L4. I use LPUART to cummunicate between the two MCU.

From my understanding the transparent mode is the best for my application as it will redirect the data from the phone directly to the LPUART.

 

The issue that i'm facing is that when I run the WB in transparent mode it's not advertizing (I use NRFconnect).

I use stm32wb5x_BLE_Stack_full_extended_fw.bin stack as mentioned in the transparent mode exemple readme.

 

The WB was advertizing when I use stm32wb5x_BLE_Stack_full_fw.bin stack with a custom template server. It means that my hardware is OK (The LPUART work fine too when I didn't use the WB as a BLE project).

 

I don't really know what I am doing wrong here.

 

Any help would be great!

 

Best regards,

Best answer by FilipKremen

Hello,

for BLE TM application, it's necessary to start the advertising with HCI command, it's not enabled from application start.

 

Best regards,

Filip Kremen

2 replies

FilipKremen
ST Employee
November 5, 2025

Hello,

could please send me the log from STM32CubeMonitorRF when you click on "start advertising"?

Thank you.

Best regards,

Filip Kremen

Associate
November 5, 2025

Hello,

 

Thank you a lot for your answer.

Actually I'm  not able to use STM32CubeMonitorRF as I can't connect my board to a computer via UART (I only have a SWD connection on my custom board).

800px-Connectivity_WBA_TM_connection.png

My understanding is that I can use the Transparent mode to cummunicate with an another STM32 via UART (as explain in AN5289 8.1.2 and shown in the image above).

If so, I am able to send data to the STM32WB from a STM32L4 via LPUART.

 

You say that I need to click on "start advertising" on STM32CubeMonitorRF. So, does it means that even if I don't use STM32CubeMonitorRF I need to send a command (with HCI?) to start the advertising?

 

Best regards,

 

Baptiste

FilipKremen
FilipKremenBest answer
ST Employee
November 10, 2025

Hello,

for BLE TM application, it's necessary to start the advertising with HCI command, it's not enabled from application start.

 

Best regards,

Filip Kremen