STM32H745: No device found on target on a custom board

[Hank_Schrader]

Hello,
I designed a custom PCB using the STM32H745IIT6 (LQFP176) and I cannot connect to the MCU using SWD with an ST-LINK V2. I always get “Error in final launch sequence / No device found on target”.

Hardware summary:

• VDD, VDDA, VREF+ → 3.3V

• VCAP1/2/3 → 2.2 µF

• VDDLDO → not connected

• BOOT0 → GND

• NRST → 10k pull-up + 100nF

• Board current consumption: 8.5 mA

SWD wiring:

• SWCLK → PA14

• SWDIO → PA13

• NRST → NRST

• GND → GND

• 3.3V → board 3.3V rail (sense)

• SWO not connected

• 10k resistors on SWCLK/SWDIO were removed for testing.

Observations:

• PA13 measures ~0.38–0.42 V when ST-LINK is not connected (floating)

• ST-LINK LED stays red (never turns green)

• CubeIDE: SWD, “Connect under reset”, 1000 kHz

• CubeMX power mode:  PWR_DIRECT_SMPS_SUPPLY.
  
  

Question:

What could cause SWD to fail with this configuration?

[AScha.3]

Hi,

> What could cause SWD to fail with this configuration?

Most times hardware, power setting vs real setup; or wrong connected/bad soldering/contacts.

So whats at Vcap ? (core voltage)

+

try connect with CubeProgrammer , under reset. (your V2 is genuine or a "stick" ? this might not work.)

[Andrew Neil]

Welcome to the forum.

Please see How to write your question to maximize your chances to find a solution for best results.

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@Hank_Schrader wrote:

I cannot connect to the MCU using SWD with an ST-LINK V2. ?

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Is it a genuine SY-Link?

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

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@Hank_Schrader wrote:

 I always get “Error in final launch sequence / No device found on target”.?

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Where, exactly, do you get that?

Please show the full log, and screenshots of any pop-up messages.

See:

How to solve connection errors when connecting and programming the STM32 target board.

How to solve debugger connection issues.

[mƎALLEm · Accepted solution]

Hello @Hank_Schrader and welcome to the ST community,

You said:

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@Hank_Schrader wrote:

• CubeMX power mode:  PWR_DIRECT_SMPS_SUPPLY.

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But according to your schematic, SMPS is almost not connected.

From the RM0399 / figure 22, this is the hardware configuration for the direct SMPS:

The question is, how did you design your board? did you refer to any reference design? 

NUCLEO-H755 board schematics for example?

The following are the different HW power config listed in the reference manual. Did you refer to the documentations: reference manual, the datasheet or the AN4938 before starting your design?:

[Hank_Schrader]

Hi Andrew, thanks for your reply.

My ST-LINK V2 is genuine.
I still get “No device found on target”, even when using CubeProgrammer with “Connect under Reset”.

My board uses an STM32H745BI with only a 3.3 V LDO (no SMPS).
Some power pins like VDDLDO_x, VDDSMPS, VBAT were left unconnected, so I think this wrong power configuration might be preventing VCORE from powering up, causing the SWD error.

VCAP pins have 2.2 µF.

I can provide logs/screenshots if needed.

Thanks.

[mƎALLEm]

The question has been answered. Your issue is in your HW especially the power config. The follow-up is here