I've just bought Nucleo-H745ZI-Q board, installed STM32CubeIDE and generated first project with FreeRTOS and blinking LED on PE1. It also worked, I could download compiled firmware and debug it. Nothing else was connected to Nucleo.

[AKise]

I wanted to try it once more again and STM32CubeIDE can't upload anything and shows me a message it can't connect to target MCU. What should it mean? How can it go broken??? I am very disappointed, nothing connected and MCU is out now. Are you really serious???

[Piranha]

No worries, that is just ST's idiot made software examples. Look for a "connect under reset" and configuring DBGMCU_CR register.

P.S. H7 is the most complex and therefore most inappropriate series for a beginner.

[Tilen MAJERLE]

Nucleo boards uses DCDC configuration for power, while (I can only assume) you have configured it (by default) to use internal LDO config. This is one of the potential problems you may face.

If you have started your project from board selector for Nucleo-H745, this setting has been properly adjusted. Configuration is under RCC -> Supply source

[AKise]

Yes, I have used the default settings of the STM32CubeIDE, it means HSI clock and PWR_LDO_SUPPLY. But why could it destroy the possibility to flash the MCU permanently?

[AKise]

Hello, thank you for you reply, but I have already configured the ST-Link connection as "connect under reset", it doesn't help at all.

I have also controlled the clock of the default project (I really think it's a stupid idea not to mount the external oscillator to save some cents), everything was just fine (HSI clock chosen), I have also selected Flash1 as a destination, so far so good. It works till I have disconnected the board, afterwards no blinking at all. And no connection to target also. I haven't even used any of the pins or connectors of the board. And I am not a beginner, I have already worked with a lot of ST MCUs and MCUs from other manufacturers.

[Tilen MAJERLE]

Remote power from Nucleo board, bridge pins 5 and 7 on CN11 connector (VDD and BOOT0 pin), then apply power to the board.

Go to STM32CubeProgrammer, connect to the board and erase flash.

[AKise]

Thank you, I can reflash the board now. But after the board is disconnected I can't access the MCU again and have to repeat this action with BOOT0 pin. What is the reason of such behavior? I have already reconfigured the power supply to POWER_EXTERNAL_SOURCE_SUPPLY, but it seems not to help with the problem.

[Tilen MAJERLE]

Do not solder pins 5 and 7, only bridge when you need to erase if you entered dead-lock. In CubeMX, you have to use DIRECT_SMPS option.

[AKise]

I haven't soldered this pins, I just use a jumper to close them. So I can re-enter the flashing after connecting pins and also can debug the firmware, but after disconnecting the board it probably goes to the dead-lock again. Where can I find the DIRECT_SMPS option? I don't see it under RCC tab of the embedded Cube (it means CubeMX integrated within STM32CubeIDE).

[Tilen MAJERLE]