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Explorer II
March 19, 2025
Solved

Most basic setup for SWD to work?

  • March 19, 2025
  • 3 replies
  • 778 views

Hello, i need help with na stm32l031k6, I want to just start the processor and read it with an st-link v2, I have connected BOOT0 to GND(i haven't added a 10k resistor, but that shouldn't be the problem ), NRST with pull-up 1k to VDD, VDDA and VDD are connected together. From what I read online I can pass without the external crystal because there is an internal one. So when I connect the VDD to 3v3 on the st-link, the GND to the st-link GND, SWCLK to PA14, SWDIO to PA13 and the chip isn't recognized. I have ruled out an faulty st link because it recognizes a blue pill f103 board. Please tell me if I am forgetting something

    This topic has been closed for replies.
    Best answer by LubO_o

    Turns out I have switched the SWDIO and SWCLK pins, otherwise everything worked!

     

    3 replies

    Super User
    March 19, 2025

    Rather than try to describe your circuit in words, please use a schematic - it's far clearer.

    You also need some decoupling caps.

    See the datasheet and AN4467 for power supply connections.

    https://www.st.com/resource/en/datasheet/stm32l031k6.pdf

    https://www.st.com/resource/en/application_note/an4467-getting-started-with-stm32l0xx-hardware-development-stmicroelectronics.pdf

     


    @LubO_o wrote:

     From what I read online I can pass without the external crystal because there is an internal one


    Correct (although, strictly, it's not a crystal - it's an RC oscillator)

     


    @LubO_o wrote:

     when I connect the VDD to 3v3 on the st-link


    What ST-Link do you have?

    Note that a genuine ST-Link does not provide power to the target

    See: How to recognize a genuine ST-LINK/V2 versus a cloned one

    In particular: https://community.st.com/t5/stm32-mcus/how-to-recognize-a-genuine-st-link-v2-versus-a-cloned-one/tac-p/703663/highlight/true#M965

     

    PS:


    @LubO_o wrote:

     the chip isn't recognized


    Using what tools?

    Show any error messages & logs you get.

     

    Note that keeping your wiring short & tidy is important. Wiring should be kept short, neat, and direct - with the minimum of joints.

    Be particularly wary of solderless breadboards, cheap "dupont" style headers, etc:

    https://community.st.com/t5/others-hardware-and-software/quot-no-device-found-on-target-quot-trying-to-flash-xm125-radar/m-p/782641/highlight/true#M31139 

     

    More tips on resolving debugger connection issues here:

    https://community.st.com/t5/stm32-mcus/how-to-solve-debugger-connection-issues/tac-p/698105/highlight/true#M956 

     

    Super User
    March 20, 2025

    The minimum required connections are GND, SWDIO, SWCLK, and the chip must be powered.

    Perhaps a bad programmer or mismatched connections. Works on F103 doesn't mean it works on other chips.

    LubO_oAuthorAnswer
    Explorer II
    March 22, 2025

    Turns out I have switched the SWDIO and SWCLK pins, otherwise everything worked!