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STM32F446 Custom board, Target Not Found using STLinkV3-Set

Associate III

I have a custom STM32 Board that is supposed to act as a flight computer. Currently I am having trouble connecting to the STM32F4 chip over SWD.

I am using a STLinkV3.

I can read the following voltages:

  • Vdd = 2.4V
  • Vda = 3.3V
  • Boot0 = 2.4V
  • Boot1 = GND
  • NRST 2.4V
  • Vcap = 1.3V

I get the following error when connecting over openocd:


xPack Open On-Chip Debugger 0.12.0+dev-01312-g18281b0c4-dirty (2023-09-04-22:32)
Licensed under GNU GPL v2
For bug reports, read
Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : clock speed 2000 kHz
Info : STLINK V3J13M4B5S1 (API v3) VID:PID 0483:374F
Info : Target voltage: 3.300200
Error: init mode failed (unable to connect to the target)


And the following error when trying to connecting using STM32CubeIDE:


Starting server with the following options:
        Persistent Mode            : Disabled
        Logging Level              : 1
        Listen Port Number         : 61234
        Status Refresh Delay       : 15s
        Verbose Mode               : Disabled
        SWD Debug                  : Enabled

Target no device found

Error in initializing ST-LINK device.
Reason: No device found on target.


My power system might be limiting current supply to the board to 50mA. Which when looking into it should be fine.
The STLinkV3-Set is detected by my computer, as seen in the following image.


The full schematic is attached as a file to this post.

Same is true for the full definition image of the printed board.

Any suggestions or help would be greatly appreciated, I am basically at my wits end with this.


Karl Yamashita
Lead II

Your BOOT0 should be pulled low, not high. 

I wanted to use the System Memory when configuring the bootloader, is there a particular reason that would be a bad idea when connecting over SWD?

I have a way to set the Boot0 pin to low using one of the switches. So I will try that!