I cannot connect ST-LINK/V2

[YIshi.1]

I created a new board using STM32L431CBT6. The initial programming of the board was successful. However, once a program was written, I found that it couldn't be modified again. I suspected it might be related to Boot settings, so I tried changing Boot0 to High, NRST to Low, and various other attempts, but ultimately I couldn't access it. I thought it might be because I didn't set Debug to Serial Wire in SYS, but it seems unrelated.

I am using STM32CubeProgrammer as the tool. When I try to access the board using a Chinese-made (purchased on Amazon) ST-LINK/V2, I cannot access it. However, writing was possible on the first attempt with this device.

Simply connecting it, the Serial number becomes corrupted, and it cannot be connected. 

Therefore, to check if ST-LINK is properly connected, I change Shared to Enable. 

Updating Media

Then, the Serial number is displayed correctly. However, when I try to connect in this state, it says there is no target.

So, when I revert Shared to Disable and attempt to reconnect, the Serial number disappears (returns to the original single-digit value), and an error "UR connection mode is defined with the HWrst reset mode" occurs. 

At this point, I decided to check my Nucleo-F401RE. It recognizes it properly and connects without any issues. Boot0 remains Low, and it connects without needing any resets.

So, I considered using the ST-Link part (the longer side) of this board to connect to the STM32L431CBT6 board I made by removing the ST-Link Jumper. In this case, it recognizes it properly, and the device is correctly identified.

In the end, does it mean that the ST-Link/V2 purchased on Amazon is not working properly? The packaging appears to be genuine ST product.

[STTwo-32]

Hello @YIshi.1 

If you are using a genuine product, it should work normally without any problem if you are doing the necessary configurations. To make sure it is a genuine product, take a look at this post.

Best Regards.

STTwo-32 

[Tesla DeLorean]

As you programmed it once, probably not an issue with the ST-LINK/V2

Custom board? Show relevant portion of the schematic.

Pull BOOT0 HIGH, and power cycle the board.

[YIshi.1]

I bought below one.

https://www.amazon.co.jp/gp/product/B0BV9QP9D2/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

Standard STMicroelectronics distributors are below(I can access them).

DigiKey/RS-COMPONENTS

After purchasing from them, I'll try again and report it.

Thank you.

[YIshi.1 · Accepted solution]

There was a delay due to shipping problems in the US, but I received the official ST-Link/V2 today (purchased from the DigiKey site from the ST official site).

After connecting, there were no problems at all.
I pulled down the Boot0 pin at 10K, didn't touch nBoot1 (didn't change it, left it at its initial value), and didn't change the Debug mode, so there was no problem at all (There was a site that told you to set it to 'Serial Wire', but you don't have to do anything).).

Below is the initial screen of CubeProgrammer. ST-Link/V2 is recognized from the beginning.

According to the product description of the device I bought on Amazon, it does not say that it is compatible with STM32-related software. So it may not be a complete counterfeit product.

I will post a photo of the device for reference.
The one on the left is the official product, and the one on the right is the one I bought on Amazon.They look exactly the same, but operate differently.