I got two STM32H735 Discovery kits (STM32H735G-DK) and broke them somehow by connecting both via USB at the same time.

A) What causes these problems and what can be done to avoid them?
B) What can be done to revive the boards?

Question

I performed the following steps:1) Set JP7 to STLK2) Connect USB -> Demo starts correctly3) Flash a simple self-written code (sets LED to state of user-button) via OpenOCD -> ST-Link works4) Flash a second self-written code (sets both LED to state of user-button) via OpenOCD -> works -> my own code did not break flashing5) Performed Steps 1-4 with a second Eval board -> works6) Copied the OpenOCD config twice and added the two serial numbers of the boards7) Connected both boards via USB (no other connection) and tried adressing them separately -> did not work8) Disconnected both boards, reconnected one, retried step 4 -> did not work. The button/LED-Program does not work any more.Since I couldn't rule out damages like ESD, I bought two new boards.9) Flashed board #3 -> works10) Flashed board #4 -> works11) Connected boards #3 and #4 (connected with CAN-wires in this case) WITHOUT flashing -> boards don't start up any more12) STM32CubeProgrammer does find the ST-LINK, but not the MCU.Further notes:* Pressing the reset button does not change anything on the boards now.* Holding reset during CubeProgrammer run has no effect.* Specifying -rst or -hardRst has no effect.* The flashing itself does not seem to be the problem, because it occurred between two steps where no flashing occurred.* Since it is reproducible by connecting two boards, external influences can be dismissed.* Output of CubeProgrammer and dmesg:-------------------------------------------------------------------
 STM32CubeProgrammer v2.7.0 
 -------------------------------------------------------------------
 
ST-LINK SN : 004500413438510C34313939
ST-LINK FW : V3J7M2
Board : STM32H735G-DK
Voltage : 3,29V
Error: No STM32 target found!
2nd connect tentative with a lower frequency (8MHz)
ST-LINK SN : 004500413438510C34313939
ST-LINK FW : V3J7M2
Board : STM32H735G-DK
Voltage : 3,30V
Error: No STM32 target found![624399.372547] usb 1-2: new high-speed USB device number 90 using xhci_hcd
[624399.521018] usb 1-2: config 1 interface 2 altsetting 0 endpoint 0x84 has an invalid bInterval 255, changing to 11
[624399.521497] usb 1-2: New USB device found, idVendor=0483, idProduct=374e, bcdDevice= 1.00
[624399.521501] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[624399.521504] usb 1-2: Product: STLINK-V3
[624399.521506] usb 1-2: Manufacturer: STMicroelectronics
[624399.521508] usb 1-2: SerialNumber: 003200273438510734313939
[624399.539360] usb-storage 1-2:1.1: USB Mass Storage device detected
[624399.539572] usb-storage 1-2:1.1: device ignored
[624399.553135] cdc_acm 1-2:1.2: ttyACM0: USB ACM device
[624405.442207] usb 1-2: USB disconnect, device number 90
[624413.572612] usb 1-2: new high-speed USB device number 91 using xhci_hcd
[624413.721031] usb 1-2: config 1 interface 2 altsetting 0 endpoint 0x84 has an invalid bInterval 255, changing to 11
[624413.721513] usb 1-2: New USB device found, idVendor=0483, idProduct=374e, bcdDevice= 1.00
[624413.721517] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[624413.721520] usb 1-2: Product: STLINK-V3
[624413.721522] usb 1-2: Manufacturer: STMicroelectronics
[624413.721525] usb 1-2: SerialNumber: 003200273438510734313939
[624413.739405] usb-storage 1-2:1.1: USB Mass Storage device detected
[624413.739733] usb-storage 1-2:1.1: device ignored
[624413.753289] cdc_acm 1-2:1.2: ttyACM0: USB ACM device
[624526.776538] usb 1-2: USB disconnect, device number 91
[624558.720923] usb 1-2: new high-speed USB device number 92 using xhci_hcd
[624558.873348] usb 1-2: config 1 interface 2 altsetting 0 endpoint 0x84 has an invalid bInterval 255, changing to 11
[624558.873833] usb 1-2: New USB device found, idVendor=0483, idProduct=374e, bcdDevice= 1.00
[624558.873837] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[624558.873840] usb 1-2: Product: STLINK-V3
[624558.873843] usb 1-2: Manufacturer: STMicroelectronics
[624558.873846] usb 1-2: SerialNumber: 003200273438510734313939
[624558.892870] usb-storage 1-2:1.1: USB Mass Storage device detected
[624558.893205] usb-storage 1-2:1.1: device ignored
[624558.917493] cdc_acm 1-2:1.2: ttyACM0: USB ACM device
[624591.435057] usb 1-2: USB disconnect, device number 92
[624611.384936] usb 1-1: new high-speed USB device number 93 using xhci_hcd
[624611.533421] usb 1-1: config 1 interface 2 altsetting 0 endpoint 0x84 has an invalid bInterval 255, changing to 11
[624611.533904] usb 1-1: New USB device found, idVendor=0483, idProduct=374e, bcdDevice= 1.00
[624611.533907] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[624611.533911] usb 1-1: Product: STLINK-V3
[624611.533913] usb 1-1: Manufacturer: STMicroelectronics
[624611.533916] usb 1-1: SerialNumber: 003200273438510734313939
[624611.896936] usb-storage 1-1:1.1: USB Mass Storage device detected
[624611.897262] usb-storage 1-1:1.1: device ignored
[624611.929503] cdc_acm 1-1:1.2: ttyACM0: USB ACM device
[624625.020963] usb 1-2: new high-speed USB device number 94 using xhci_hcd
[624625.169325] usb 1-2: config 1 interface 2 altsetting 0 endpoint 0x84 has an invalid bInterval 255, changing to 11
[624625.169805] usb 1-2: New USB device found, idVendor=0483, idProduct=374e, bcdDevice= 1.00
[624625.169809] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[624625.169812] usb 1-2: Product: STLINK-V3
[624625.169814] usb 1-2: Manufacturer: STMicroelectronics
[624625.169817] usb 1-2: SerialNumber: 004500413438510C34313939
[624625.533826] usb-storage 1-2:1.1: USB Mass Storage device detected
[624625.534232] usb-storage 1-2:1.1: device ignored
[624625.534745] cdc_acm 1-2:1.2: ttyACM1: USB ACM device
[624631.559510] usb 1-2: USB disconnect, device number 94
[624636.444603] usb 1-1: USB disconnect, device number 93
[624649.009002] usb 1-1: new high-speed USB device number 95 using xhci_hcd
[624649.157507] usb 1-1: config 1 interface 2 altsetting 0 endpoint 0x84 has an invalid bInterval 255, changing to 11
[624649.158122] usb 1-1: New USB device found, idVendor=0483, idProduct=374e, bcdDevice= 1.00
[624649.158123] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[624649.158123] usb 1-1: Product: STLINK-V3
[624649.158124] usb 1-1: Manufacturer: STMicroelectronics
[624649.158124] usb 1-1: SerialNumber: 004500413438510C34313939
[624649.521403] usb-storage 1-1:1.1: USB Mass Storage device detected
[624649.521754] usb-storage 1-1:1.1: device ignored
[624649.522314] cdc_acm 1-1:1.2: ttyACM0: USB ACM device

Tesla DeLorean · Accepted Answer

Are these boards powered from the same power domain, with well bonded common grounds?

You could try Switching (SW1?) the boards to boot from ROM (BOOT0=HIGH), completely cycle the power (removed ALL connections) a couple of times, and then see if the STM32 Target can be found, if so erase the device.

KNeus.1 · Answer

The first time, the boards did not have any direct connection. Both only had the single USB connection to the PC.

I tried your suggestion and I was able to perform a full erase and now I can get a connection again. Thank you a lot!

Digging more, I found out that this deadlock seems to be common when messing up the SMPS/LDO configuration: https://community.st.com/s/question/0D50X0000BD2xd9/cubemx-is-missing-the-pwrdirectsmpssupply-option-under-rccsupplysource

Apparently, it wasn't because I connected two boards, but because I disconnected/power-cycled them during this process.

I took the default parameters from the discovery kit example provided by CubeMX - but apparently they don't work...

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