Add support for NUCLEO-H755ZI-Q board

[Igor-Misic]

This pull request for board NUCLEO-H755ZI-Q servers as tutorial on how to add new board to IMBootloader.

How to add new board?

Add the new board to the Makefile (RAM support is optional, depending on whether you want it to be able to run from RAM):

nucleo_h755zi:
	${MAKE} stm32h7xx BOARD=NUCLEO_H755ZI BOARD_FILE_NAME=$@

nucleo_h755zi_ram:
	${MAKE} stm32h7xx_ram BOARD=NUCLEO_H755ZI BOARD_FILE_NAME=$@

In this case, we had an STM32H755ZI MCU, which is slightly different from previously supported H7 MCUs. This one has two cores, so we needed to enable the STM32 HAL for it. This change can be seen in the Makefile.stm32h7xx file.

ifeq ($(BOARD), NUCLEO_H755ZI)
  C_DEFS += \
  -DCORE_CM7 \
  -DSTM32H755xx

The NUCLEO-H755ZI-Q board uses an integrated SMPS (Switched-Mode Power Supply) as its power source. To provide flexibility, we added an option to the board_config.h file to choose between LDO and SMPS power modes.

The standard board configuration defines two LEDs and a button, if present. In this case, we added a blue button to trigger bootloader entry on boot.

#ifdef NUCLEO_H755ZI
#define LED1_Pin                GPIO_PIN_0
#define LED1_Port               GPIOB
#define LED2_Pin                GPIO_PIN_1
#define LED2_Port               GPIOE
#define LED_ON                  GPIO_PIN_SET
#define LED_OFF                 GPIO_PIN_RESET
#define BL_BUTTON_Pin           GPIO_PIN_13              //!< Button for entering in BL if pressed at boot time
#define BL_BUTTON_Port          GPIOC
#define BL_BUTTON_ON            GPIO_PIN_SET
#define BL_BUTTON_OFF           GPIO_PIN_RESET
#define BL_BUTTON_PRESS_TIME    500u                    //!< Time in [ms] needed for button to be pressed to enter in BL
#define PWR_SUPPLY              PWR_DIRECT_SMPS_SUPPLY

And don't forget to add board information to board_info.h

#ifdef NUCLEO_H755ZI
#define PRODUCT_TYPE    (const char*)("IMProject_demo-nucleo_h755zi")   // Maximum allowed size is 100 characters (101 bytes)

Finally, add the board to the README.md file and update the compile.yml file to include it in the compilation process with each pull request.

How to test it?

Example of writing an IMLedBlink application for NUCLEO-H755ZI-Q
IMProject/IMLedBlink#5