STM32F103RBT6 MCU not detected by programmer – BOOT0 pin tied to GND on custom PCB

[asking]

Hello everyone,

I have designed a custom PCB using STM32F103RBT6 and I’m facing a serious issue:
The MCU is not getting detected by the programmer.

Symptom:

When connecting via SWDIO, SWCLK, 3.3 V, and GND, both STM32CubeProgrammer and ST‑Link Utility fail to detect the target.

Power rails are verified: 3.3 V present at VDD pins, proper decoupling capacitors placed close to supply pins.

No shorts observed on the board.

Important hardware details:

Boot0 pin (on my design) is directly tied to GND by mistake – I’m wondering if this could block programming or reset behavior.

NRST pin has a 10 kΩ pull‑up to 3.3 V as recommended.

BOOT0 is pulled low (GND) on the board without Resistor, any problem?

Any advice would be greatly appreciated!
schematic snippet attached.

 

 

Thank you in advance for your help.

[Tesla DeLorean]

You don't need to remove the pull-up to measure the static state.

[asking]

Measured Voltage is 3.329V on pull up with resistor and without resistor. Also i have connected VDD to VBAT, still controller is not responding to programmer same error.

[asking]

Connected VDDA directly to VDD, it worked! means TL431 was not able to supply enough current required for operation.

[STOne-32]

Hi @asking ,

Great to see , you are able to find the root-cause !  well done.

Ciao

STOne-32.