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Associate III
February 16, 2026
Solved

STM32WBA64CIUx USART BOOTLOADER

  • February 16, 2026
  • 3 replies
  • 374 views

Hi, I have a problem with activating USART bootloader.

I use USART1. Please for details about how to going in bootloader mode. Pattern 12 in  AN2606 is super complicated for me. I use now boot pin. I put it to GND and power ON . By me MCU going in bootloader mode, software put it with J-link is not started, but STM programmer show : Activating device: KO.Please, verify the boot mode configuration and check serial port configuration. Reset your device then try again..

Please for details how to put in USART1 boot mode.

 

 

Best answer by Brussl

So after 1 week test and attempts I find problem. NEED TO CONNECT VDDUSB to VCC! This is without logic for me. I don't use USB hardware in chip.

I can't find in documents something about that.

 

3 replies

TDK
Super User
February 16, 2026

AN2606 has details for putting the chip into bootloader mode. Here they are:

TDK_0-1771249183792.png

Yes, this is complicated, but it reflects reality. Use STM32CubeProgrammer with an SWD connection to examine the state of the option bytes. There are only 5-6 values relevant here. Look up what they are for your chip and write down the values.

Ensure the pins you are using are supported. Ensure parity is set to even.

If still stuck, post pictures of your setup.

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BrusslAuthor
Associate III
February 16, 2026

Ok. I see first line :

TZEN = 1 = 0, Boot0(pin) = 0, nSWBoot0(bit) = 1 and NSBOOTADD0 [24:0] = Address(1)

nSWboot0(bit) is 1.

Boot0 pin will put to GND.

TZEN as I see doesn't matter.

What must be Address(1) ?

 

 

TDK
Super User
February 16, 2026

> What must be Address(1) ?

The superscript (1) refers to footnote 1. Look at the footnote (1) for what it needs to be:

TDK_1-1771254154147.png

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TDK
Super User
February 16, 2026

It won't help if I rewrite what it already says in AN2606.

If you want to debug, you'll need to post specifics of your setup. What pins, what board is this, what interfaces are connected. Note that the bootloader will connect to whatever talks with it first.

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BrusslAuthor
Associate III
February 17, 2026

Brussl_0-1771313833673.png

Brussl_1-1771313880742.png

Brussl_2-1771313934915.png

USB to Uart is tested on many devices.

So what should be setup bits and NSBOOTADD0 and NSBOOTADDR1 ?

Can some other pin to confuse the boot sequence ?

 

Tnx in advance

 

BrusslAuthor
Associate III
February 19, 2026

Some idea ?

TDK
Super User
February 19, 2026

I looked, nothing is jumping out at me. You should ensure other pins used by the bootloader are silent when it enters the bootloader. Putting a logic analyzer on the RX line may shed some light.

Based on your description, it sounds like it's entering the bootloader reliably but not responding on USART1 all of the time.

> The new interesting is i some time can connect it.

So sometimes it is working, which suggests connections are correct. Could there be noise on other bootloader supported interfaces?

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BrusslAuthorBest answer
Associate III
February 23, 2026

So after 1 week test and attempts I find problem. NEED TO CONNECT VDDUSB to VCC! This is without logic for me. I don't use USB hardware in chip.

I can't find in documents something about that.