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Fahad Mirza
Visitor II
June 21, 2017
Question

ST-Link/V2 and ST-Link/V2-1 issue

  • June 21, 2017
  • 4 replies
  • 2504 views
Posted on June 21, 2017 at 18:03

I have a custom board with STM32L051 on it. I am using an example from ST (I-Cube_lrwan). For some reason, once I load the firmware I cannot access the MCU anymore using ST-Link Utility and ST-Link/V2. It always throw 'Cannot connect to target'. But if I press the reset button before I press 'Connect' (in ST-Link Utility) and release the button right after I press 'Connect' , ST-Link/V2 can find my MCU.

But... when I use ST-Link/V2-1 from a Nucleo Board, it works perfectly. To me, its like ST-Link/V2-1 can reset the MCU properly where ST-Link/V2 cannot for some reason.

Can anyone suggest me what should I do if I want to use ST-Link/V2, in my case?

#st-link
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    4 replies

    B
    Bogdan Golab
    Visitor II
    June 21, 2017
    Posted on June 21, 2017 at 22:50

    I would try to upgrade the ST-LINK firmware first. Use the build-in ST-Link capability to do it. Sometimes you will need to reconnect the usb cable to enter the programming mode.

    O
    Olivier GALLIEN
    Technical Moderator
    June 22, 2017
    Posted on June 22, 2017 at 10:07

    Hi

    fahadmirza

    ‌

    Do you select 'Connect under reset' mode in ST-Link Utility ?

    Does you firmware enter any low power mode or change SWD GPIO settings which can explain you can't reconnect with a normal system reset ?

    Olivier

    B
    Bogdan Golab
    Visitor II
    June 22, 2017
    Posted on June 22, 2017 at 15:05

    Sometimes you need to connect to the device under reset.

    I am talking about upgrading the firmware on ST-LINK programmer (not the target MCU).

    F
    Fahad MirzaAuthor
    Visitor II
    June 22, 2017
    Posted on June 22, 2017 at 18:34

    Hello

    Golab.Piotr

    ,

    It has the updated FW. At least that's what ST-Link is showing me (FW ver: V2.JS7 STM32+STM8 Debugger). Nucleo ST-Link FW version is V2.JM17 STM32 Debug+Mass storage

    Hi

    GALLIEN.Olivier

    ‌,

    Yes, the HW goes to low power mode (STOP mode) and change the SWDIO and SWCLK pins to analog. I did get the warning on ST-Link Utility ('Device is disconnected') right after I flash FW. For a long period of time I thought this was the problem and that's why I was using the external RESET button to flash my MCU.

    But... the ST-Link from Nucleo can access my MCU, with low-power and changed pin configuration. That's why I was wondering what are the differences between these two ST-Links

    N.B. My Nucleo board has ST-Link/V2-1 (that's what datasheet says) and the separate programmer is ST-Link/V2. And I am using 'Connect under reset'.

    O
    Olivier GALLIEN
    Technical Moderator
    June 23, 2017
    Posted on June 23, 2017 at 10:23

    For a connect under reset the ST-LINK drive the NRST signal of the MCU. 

    On Standalone V2 probe the CN3.15 is driven and should be connected to NRST of your MCU.

    Is it the case ? 

    F
    Fahad MirzaAuthor
    Visitor II
    June 23, 2017
    Posted on June 23, 2017 at 18:51

    I am not sure which pin is CN3.15. The ST-Link I have is shown below. RST is connected with my MCU's NRST.

    0690X00000607KiQAI.png

    I hope I am not having issues because it is not made by ST. Do you think that's a possibility?

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