Debugger does not connect. Can it be RDP level 2 or "secure mode"?

[Pavel A.]

I got two these STM32H750 boards. Wired up a ST-LINK, and one of them works fine.

But the second one is not accessible by debugger.

Following is output of CubeIDE debugger:

STMicroelectronics ST-LINK GDB server. Version 5.3.2
Copyright (c) 2019, STMicroelectronics. All rights reserved.
 
Starting server with the following options:
 Persistent Mode : Disabled
 Logging Level : 1
 Listen Port Number : 61234
 Status Refresh Delay : 15s
 Verbose Mode : Disabled
 SWD Debug : Enabled
 
Target no device found
 
Error in initializing ST-LINK device.
Reason: No device found on target

And this is output of CubeProgrammer:

STM32CubeProgrammer API v2.1.0
ST-LINK SN : xxxxxxxxxxxxxxxxxxx
 ST-LINK FW : V2J34S7
Voltage : 1.57V
Error: ST-LINK error (DEV_TARGET_CMD_ERR)
ST-LINK SN : xxxxxxxxxxxxxxxxxxxxxx
ST-LINK FW : V2J34S7
Voltage : 0.55V
Error: ST-LINK error (DEV_TARGET_CMD_ERR)
ST-LINK SN : xxxxxxxxxxxxxxxxx
ST-LINK FW : V2J34S7
Voltage : 0.00V
Error: No STM32 target found!

The board is alive, it runs some pre-installed firmware that blinks the LEDs. Looks exactly as the other (good) one.

Can it be a symptom of level 2 activated, or the new STM32H75x "secure mode"?

Thanks,

-- pa

[S.Ma]

Have you tried mass erase?

[Pavel A.]

> Have you tried mass erase?

No. Cannot connect with any tool: programmer, ST-LINK utility.

[Bob S]

I don't have direct H7 experience,m but on other STM32 families, when RDP2 (or RDP1) protection is set the ST-Link will still connect and "see" the device, it just won't let you do much. Since you are seeing "no device found" I would suspect the SWI interface. Though looking at the schematic from the other thread there isn't anything there except header/connector and CPU. Double-check the solder joints???

[Tesla DeLorean]

Voltage seems very low. Check connection soldering and continuity of both VCC and GND.​

[Pavel A.]

Yep. Soldering it was ((