How do I regain ST-Link connectivity with Nucleo-H745ZI-Q with BOOT_CM7 = 0 and BOOT_CM4 = 1

[Yoichi Shinoda]

While fiddling with H745 board to investigate how dual core works, after modifying option byte to BOOT_CM7 = 0 and BOOT_CM4, STM32CubeProgrammer (nor STLINK-gdbserver) refuses to connect to the board with "Error: No STM32 target found". The ST-Link itself is okay. Here is a log from the programmer.

22:31:39 : ST-LINK SN : 002F003D3137510E39383538
22:31:39 : ST-LINK FW : V3J5M2
22:31:39 : Voltage : 3.30V
22:31:39 : No STM32 target found!
22:31:39 : ST-LINK SN : 002F003D3137510E39383538
22:31:39 : ST-LINK FW : V3J5M2
22:31:39 : Voltage : 3.30V
22:31:39 : Error: No STM32 target found!

How do I regain access to the board?

[flyingchris]

I would be interested in the patch too. I'm running into the same problem here.

[RBharol]

I had the same issue. After I disabled CM7 boot, the STLink won't connect. I am using STM32H745I-DISCO board. I did this to work around it.

1) Removed power and Enabled BOOT 1. Please note that all you have to do is short the pads on R144. No need to remove R143 and put on R144. It is too tiny to handle. You will mess with pads and make it unusable. Just short R144 pads with some solder. It will put it in BOOT1 mode.

2) Power up and connect. Open STLink Utility (not the STLink programmer) and in Target->Settings select the Access port to 'access port 3'.

3) Connect.

4) Got to 'Target->Option Bytes' and Enable M7 Boot. Erase flash.

5) Now you should be able to connect via STLink Programmer as well.

6) Once confirmed connection, power off and Un-Short the R144 pads. It should now work.

[YVeda.1]

Can I get the patch or is it already deployed in the current release v2.7.0?

I am facing a similar problem with the NUCLEO-H745QI board where the STM32CubeProgrammer is not detecting the target, getting `No STM32 target is found` error. This happened after programming the code generated by CubeMx with Max clock frequency.

Not sure the problem I'm facing is similar to this thread.

[Houda GHABRI]

Hi @YVeda.1​ ,

Yes it is already implemented in V2.7.0.

Do not hesitate to open a new thread if the issue still exists for you.

Houda

[jhochreiter]

*** me.
I also bricked my NUCLEO-H755ZI-Q eval board with modifying option byte to BOOT_CM7 = 0 and BOOT_CM4 = 1
Connected via ST-Link on USB port.
STM32CubeProgrammer v2.16.0 cannot recover the situation:
Error: ST-LINK error (DEV_CONNECT_ERR)
Any hints?

[Aouse_KHALAF]

Hi Houda GHABRI , 

I have the same problem with my NUCLEO-H745ZI-Q. Can you please share the solution with me?

Best regards

[jhochreiter]

Use the cube programmer and set the access port to 3 to communicate with the M4.
Erase the M4 Flash, if you have troubles because of clock settings.