Unable to connect to STM32F373C via SWD using STM32F072B-Discovery as ST-Link

[hartle1707]

 

Hi all,

I'm having trouble connecting to an STM32F373C on a custom PCB via STM32CubeProgrammer, using an STM32F072B-Discovery board as a standalone ST-Link/V2. The custom PCB is an open source synthesiser module and was manufactured by JLCPCB - many others have built this PCB with no issues. I've followed the correct procedure for using the Discovery board as an external ST-Link (removed CN5 jumpers, opened SB10), and wired CN4 to my PCB's dedicated SWD header which has RESET, SWCLK, SWDIO and GND pins.

**Setup:**
- Programmer: STM32F072B-Discovery (ST-Link/V2), CN5 jumpers removed, SB10 opened
- Target: STM32F373C on custom PCB
- Connection: Via dedicated SWD header (RESET, SWCLK, SWDIO, GND). Discovery board connected to Macbook using Mini USB to USB C cable.
- Software: STM32CubeProgrammer, SWD mode, various frequencies tried down to 480 kHz
- Reset modes tried: Software reset, Hardware reset, Connect under reset

**Error in CubeProgrammer:**
ST-LINK SN: 38FF68063050453420251743
ST-LINK FW: V2J46S0
Voltage: 2.92V
Error: Unable to get core ID
Error: No STM32 target found
```

**Power supply.**

- VDD, VDDA, VBAT, VDDSD and VREFSD+ pins on the STM32 have been probed and confirmed at 3.3V.

**BOOT0:** Pulled directly to GND.

**Steps already taken:**
- Swapped SWDIO and SWCLK wires
- Tried connecting with NRST disconnected (3 wire SWD only)
- Tried all reset modes
- Tried reducing SWD frequencies
- Confirmed all power rails at correct voltages
- Confirmed no missing components on PCB

I have attached pictures of the STM32CubeProgrammer error, PCB schematic, physical PCB and the ST Link connection.

Are there any other pins I should read voltages from? Are there any components I may have incorrectly ordered or orientated which could be causing the problem? The PCB should in theory work as it was once mass produced, I haven’t modified the design, and many others have had it manufactured with no issues.

Thanks

[Andrew Neil]

Did you follow carefully the User Manual instructions - particularly about SB10:

https://www.st.com/resource/en/user_manual/um1690-discovery-kit-for-stm32f0-series-microcontrollers-with-stm32f072rb-stmicroelectronics.pdf#page=13

via: https://www.st.com/en/evaluation-tools/32f072bdiscovery.html#documentation

 

While it should be possible to use the Disco board as an STLink, this does come with a few issues which complicate things.

Therefore I would strongly recommend that you get a  genuine standalone STLink:

 

 

PS: 

Sorry, I missed this bit:

I've followed the correct procedure for using the Discovery board as an external ST-Link (removed CN5 jumpers, opened SB10)

 

But you do seem to have omitted the VDD_TARGET connection.

Are you sure you have the pin numbering correct, and the wiring correct to the target?

Can you connect using CubeProgrammer?

Are you sure that the Target STM32F373C is correctly mounted, is getting correct supplies, etc?

 

I would still recommend getting a genuine standalone STLink.

[hartle1707]

Yes I have followed the instructions in the User Manual. The SWD connector is wired up correctly, I have removed the jumper from CN5 and I have removed the solder bridge from SB10 in order to use the NRST pin (confirmed with a multimeter).

I have tried connecting VDD_TARGET to the 3.3v rail on the PCB using one of the empty through hole part pads.

I have confirmed 3.3v is being supplied to VDD, VDDA, VBAT, VDDSD and VREFSD+ on the STM32.

Are there any other volatages on the STM32 you would recommend testing?

I have already tried a standalone STLink, albeit a clone. This gave me the same "target not found" error, so I purchased the discovery board which the original manufacturer recommends to flash the STM32. 

I will try a genuine standalone STLink if there is no obvious troubleshooting I can try first. What was supposed to be a DIY project to save some money is turning into quite an expensive endeavour!

[Andrew Neil]

CubeIDE is known to refuse to connect when using a fake/clone STLink.

 

Can you connect using CubeProgrammer?

Are you sure that the Target STM32F373C is correctly mounted, is getting correct supplies, etc?

 

It’s a shame that the board shorts BOOT0 to ground - otherwise you could try using the bootloader ...

[AScha.3]

As you have not connected rst, only setting “software reset” will work.

Try with the “clone” , stick, and verify swd + swc , not puzzled.

With CubeProgrammer it looks like this: 

...and after : connect :

Show, what its telling.

btw I use V. 2.19.0 , maybe try this version.

[hartle1707]

I have tried every combination of normal, hot plug, under reset, software reset, hardware reset etc. Every time I get the same ‘target not found’ error which you can see in the screenshot of my original post. 

I am really only interested in troubleshooting the PCB or the connection to the STLink at this stage as I have tried everything else.

[Andrew Neil]

I have tried every combination of normal, hot plug, under reset, software reset, hardware reset etc

Is that using CubeIDE, or CubeProgammer?