Unable to connect BlackPill via ST-link

[LucaLauro]

Hi,

When trying to connect the board via ST-link in CubeProgrammer i get the error: "No STM32 target found!..."; can't figure out what problem is preventing ST-link from finding the target.

BlackPill is working properly, i can use it via DFU, but I would like to use debug.

I tested the ST-link dongle with a NUCLEOF303RET6 and it works fine.

Then i tried using the onboard ST-link of the NUCLEO to connect the BlackPill (with the correct configuration) and had the same problem; so i think the problem may be in the BlackPill (could it be an incorrect code in the identification registers?).

I also tried different bootloaders, although i don't think they can make a difference in this case.

Board: WeAct BlackPill V3.0, MCU: F411CEU6 (original), SWDIO and SWCLK correctly configured on pins PA13 and PA14 (SWD configuration), target voltage 3.28V.

ST-link: V2 dongle, MCU: F103C8T6 (original), tried with reset pin connected, tried with various firmware versions (now v2J45S7).

CubeProgrammer: no mode and reset mode works, tried various versions (now v2.17.0). (ST-link Utility too).

What am I missing?

Thanks for your time.

[Tesla DeLorean]

That the part is not actually authentic?

Perhaps un-powered? Perhaps wrong pins?

Does it present as a DFU "STM32 BOOT DEVICE" if connected via USB and BOOT0=HIGH ?

[LucaLauro]

Thanks for your attention,

it seems an original F411 to me, maybe i'm wrong, it seems to have UFQFPN48 package correct marking layout at least.

https://www.st.com/resource/en/technical_note/tn1433-reference-device-marking-schematics-for-stm32-microcontrollers-and-microprocessors-stmicroelectronics.pdf

When connected to the ST-link it is correctly powered and the ST-link reset pulse signal works.

When connected via USB with DFU mode selected (BOOT0=HIGH) it's shown as "STM32 BOOTLOADER", a serial number is recognized too.

[Tesla DeLorean]

Ok, can you use the DFU method to program it?

On the ST-LINK side there's either a power or connectivity issue. If this is an ST-LINK off a NUCLEO, make sure the local target is disconnected.

Power the Black-Pill from same USB host as ST-LINK.

3V3 to Pin 1 (of 20-pin header)

GND to Pin 4 (or other EVEN GND pins)

SWCLK to Pin 9

SWDIO to Pin 7

Double check connectivity too PA13/PA14

[LucaLauro]

As mentioned in the first post, DFU works perfectly and i can use the BlackPill in this way.

ST-link dongle works with the F303 on the NUCLEO, but the NUCLEO ST-link (in external target configuration) gives the same error with the BlackPill. This is what made me think that the problem lies in the BlackPill.

Furthermore, the power supply from ST-link works, because programs in the F411 memory starts when the ST-link power is connected, the detected target voltage is 3.28V and, if it didn't, I wouldn't have been able to program the F303RET6 on the NUCLEO.

Something prevents the F411 to be recognized by both the ST-link dongle and the NUCLEO ST-link.

[Tesla DeLorean]

>>Something prevents the F411 to be recognized by both the ST-link dongle and the NUCLEO ST-link.

Yeah, you'll have to unpick that circuit to make a determination as to WHY

Check for continuity, check for inopportune capacitors in the path, drop the connection speed / mode

Wire up NRST so "Connect Under Reset" has some purchase..

[LucaLauro · Accepted solution]

Some time ago, after checking the board, I noticed two pads not soldered correctly, coincidentally they were pin 36 (VDD) and pin 34 (PA13 of the UFQFPN48 package); but I left the hardware work as a last try, being the most risky.

Having considered all possible causes of malfunction not strictly hardware-related I decided to check this case too, trying to add solder where it was missing.

After adding it... surprise! it works flawlessly in every mode.
Seems that it was just a faulty solder, despite it being an original WeAct BlackPill.

Thanks so much for your time.