How is it possible to power the Nucleo-144 board with an external NEGATIVE power supply (VDD= 0V, VSS= -3v3)?

[TDK]

Voltage is relative. As long as VDD - VSS = 3.3V, it will work. However, if you have other things connected to the board that think VDD = GND, you're going to have issues.

Information on powering the board from 3.3V is in the user manual:

https://www.st.com/resource/en/user_manual/dm00244518-stm32-nucleo144-boards-mb1137-stmicroelectronics.pdf

[HLabi.1]

According to Table 7 (page 19) and paragraph "External power supply input: + 3.3 V" (page 23), there are two possibilities:

- ST-LINK PCB is cut

- SB3 and SB111 OFF (ST-LINK not powered)

So my question is: If I cut the ST-LINK/V2-1 PCB from the board, is it possible to use the ST-LINK/V2-1 (removed) to program and debug the same board (I removed from)?

According to Table 5 (page 22) and STM32CubeMX:  

VDD_TARGET --> 3V3

SWCLK   --> PA14 

GND    --> GND

SWDIO   --> PA13

NRST    --> NRST

Is it correct to connect the pins as shown in the picture?

[TDK]

Yes, it is. Note that the programmer and the board will need the same ground. I'm unsure if SWDIO/SWCLK are broken out into pins somewhere, but provided you can get at those somehow, you can program the board.

[HLabi.1]

I made the connections as shown in the picture. LD4 and LD6 are turned ON.

I tried to run a test program on the board.

I chose the "GPIO_EXTI" from the repository (..\STM32Cube\Repository\STM32Cube_FW_F4_V1.25.2\Projects\STM32F429ZI-Nucleo\Examples\GPIO\GPIO_EXTI).

After running the program, the microcontroller fails on "HAL_RCC_OscConfig(&RCC_OscInitStruct)".

The same problem if I choose another example from the repository.

[TDK]

The clock source used in that example (and probably others) comes from the ST-Link, which you've cut off, so no clock source.

https://github.com/STMicroelectronics/STM32CubeF4/blob/master/Projects/STM32F429ZI-Nucleo/Examples/GPIO/GPIO_EXTI/Src/main.c#L111

You'll need to modify it to use the internal HSI instead.

[HLabi.1]

I replaced HSE with HSI:

//RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;

 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;

But it didnt work. I have the same problem.

[TDK]

Generate a working HSI clock initialization with CubeMX and copy it over to the example code. Changing one random line and hoping for the best isn't a recipe for success.

[HLabi.1]

CubeMX uses nearly the same configuration.

Here is the only difference:

 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_HSE;

RCC_OscInitStruct.HSIState = RCC_HSI_ON; 

RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;

It doesn't work either.

[TDK · Accepted solution]

> RCC_OSCILLATORTYPE_HSE
Don’t try to initialize the HSE. Your board doesn’t have one. Also dont use it as the PLL source.