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Debugging Nucleo-H723ZG with Segger J-Link?


I am trying to debug my Nucleo H723ZG board using the CN5 (MIPI10) and a Segger J-Link Pro. But I have tried both methods described in the UM2407 6.3.3 "Using an external debug tool to program and debug the on-boards
STM32H7" and neither allows the J-Link to connect to H7. When I attempt to start a debugging session, I get the following error message:


And the J-Link startup dialog looks like this:




SEGGER J-Link GDB Server V7.84e Command Line Version

JLinkARM.dll V7.84e (DLL compiled Feb  1 2023 16:41:41)

Command line: -port 2331 -s -device STM32H723ZG -endian little -speed 4000 -if swd -vd
-----GDB Server start settings-----
GDBInit file:                  none
GDB Server Listening port:     2331
SWO raw output listening port: 2332
Terminal I/O port:             2333
Accept remote connection:      localhost only
Generate logfile:              off
Verify download:               on
Init regs on start:            off
Silent mode:                   off
Single run mode:               on
Target connection timeout:     0 ms
------J-Link related settings------
J-Link Host interface:         USB
J-Link script:                 none
J-Link settings file:          none
------Target related settings------
Target device:                 STM32H723ZG
Target device parameters:      none
Target interface:              SWD
Target interface speed:        4000kHz
Target endian:                 little

Connecting to J-Link...
J-Link is connected.
Firmware: J-Link Pro V4 compiled Sep 22 2022 15:00:37
Hardware: V4.00
S/N: 174403180
Feature(s): RDI, FlashBP, FlashDL, JFlash, GDB
Checking target voltage...
Target voltage: 3.32 V
ERROR: Failed to listen at socket (Err = -1)
ERROR: Failed to open listener port 2331
Restoring target state and closing J-Link connection...
Shutting down...
Failed to open listener port 2331




This appears to be an issue with the GDB server, but I can't figure out why? Or perhaps it might be that the CPU is not running?

Any thoughts would be appreciated.






the CN5 connects to the onboard st-linkV3 . did you disable this ? 

so dont connect j-link , use the onboard st-linkV3 , connect PC to CN1 USB (micro usb probably).

is it (still) working?

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"so dont connect j-link , use the onboard st-linkV3 ,"

I need to use the J-link for more complex dual-board debugging. I don't want to use the on-board ST-Link.

"the CN5 connects to the onboard st-linkV3"

..not according to the documentation. CN5 is the MIPI debugging connector as shown below. 


"did you disable this ? "

I did jumper the STLINK-RST pin, but this appears to also disable the power supplied to the CPU. My J-Link cannot connect to the CPU.

Again, I prefer to use the more powerful J-Link Pro for debugging. How can I do this with the Nucleo board?



ok, so you want/need j-link...hmm.

look at circuit:

jumper the STLINK-RST pin, ok. but seems, hse + lse not fitted on board, so you cannot run with external clocks, except you have mount them on board + connect (solder bridges); (and st-link under reset -> no clock to H7 cpu !)

then decide, how to power it...and st-link needs to be powered also, even in reset, because connects also to cn5.

you should get connect with j-link, "under reset", because cpu starting then on internal HSI clock.

so: some work, to run it with j-link. 🙂

If you feel a post has answered your question, please click "Accept as Solution".

Probably move jumper from JP3 to JP1. And JP2 to CHGR if using USB-C to power.

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Tesla, "Probably move jumper from JP3 to JP1. And JP2 to CHGR if using USB-C to power"

This does let the J-Link to connect to the MCU, but as mentioned by Ascha, the chip is now not receiving a clock from the debugger. Seems a bit confusion that the documentation clearly implies that this can be done.

6.3.3 Using an external debug tool to program and debug the on-boards
There are two basic ways to support an external debug tool:
1.Keep the embedded STLINK-V3E running.
Power on the STLINK-V3E at first until the COM LED lights RED. Then connect your external debug tool through the MIPI-10 debug connector (CN5).
2. Set the embedded STLINK-V3E in the high-impedance state:
When the STLK_RST jumper (JP1) is ON, the embedded STLINK-V3E is in the RESET state, and all GPIOs are in high impedance. Then it is possible to connect the external debug tool to the debug connector (CN5).