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Getting ST-LINK-V3 MODS to run after previous used of nucleoboards.

Senior III


i was hoping, that the Link-V3 would just work, after i used nucleo boards already. But i was dissapointed. I use the GDB server, and it says:

ST-Link enumeration failed

Error in initializing ST-LINK device.
Reason: ST-LINK DLL error.

I just checked a Nucleo board, and there is no problem.

The installation of the driver worked without errors.




Accepted Solutions
Senior III


While trying many things, i disconnectes NRST. But i still can program the target.

I had to enter the frequency in the gdb server comman line!

View solution in original post


Can you connect with STM32CubeProgrammer? If not, at which stage does it fail? Does the ST-link show its serial number? Does the target voltage show up and is it valid?

Since this is custom hardware, was it ever working correctly or is this a first try? Does it have power, are pins connected correctly, is VCAP correct, etc?

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It now works. I think i may have to turn / plugin the cables in a certain order.

But i now have this Error:

Error message from debugger back end:
Error finishing flash operation
Error finishing flash operation

I asked 6 questions, you answered 0 of them. If you want help by me, you're going to have to pitch in a bit more.

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Since the original error message is gone, i did not consider answering the question. But i do so now:

- I dont know i which way i should connect with the programmer.

- The GDB server now works, but running the cube programmer, it reads the ST-LINKV3 serial number and firmewareversion. It shows a voltage of 0.01V, but i confirmed, that the target has its 3.3V.

The current error massage is: "Error: No STM32 target found! If your product embeds Debug Authentication ..."

It is the first connect of this prototype. I was already wondering, why NRST was not on this ST-LINK.


I found out, that it is recognized, when the target is powered off.

What is VCAP?

Okay, it sounds like the computer can see the ST-Link okay and that the problem is between the st-link and the target mcu. Is that wired up correctly?

Since STM32CubeProgrammer reports that the target voltage is 0.01 V, perhaps the target isn't powered. I know you said that it is, but then we need to answer why STM32CubeProgrammer disagrees. Can you provide the schematic? Can you probe the T_VCC pin directly to see if it's reported?

T_NRST is pin 31 on that device and should be connected to NRST on the target chip.

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I have verified, that the labels are connected to the right pin. They also have a 5k resistor before the target.

I could verify, that there is a clock on the clock line, and some data on the DIO line.

One very interesting thing: there is a reset pulse right in the middle of a datapacket! That not so optimal.

When making the programmeradapterboard, i got a bit confused, because there is no NRST pin there. Also i could not find informations about how to connect it.

The physically connectivity to the MCU and the involvement of the resistors would be a lot more helpful here.

The ST-LINK should be able to sample and report the target voltage correctly.

The connectivity to the MCU should be pretty direct and straight forward




VCC to T_VCC to drive the target pins at the correct voltage


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What does the "T_" stand for?

Senior III

I have now made more measurements:

The signal have the right levels without a T_VCC connection.