variants: Add new Arduino boards (STM32 boards)

[soburi]

Add support for Giga R1, Portenta H7, Opta, and Nicla Vision.

We have confirmed that these compiles when used in combination with
https://github.com/arduino/zephyr/tree/zephyr-arduino-v4.2.0.
We will incorporate the changes for the migration to version 4.4 separately in the near future.
arduino#522 (comment)

Wi-Fi and relocation have been disabled compared to the original.

The functionality of analog pins to which no GPIO function has been assigned is incomplete in some boards; needs to fix separately.

As I do not have the actual boards, I have only verified the compilation.

[Copilot]

Pull request overview

This PR adds new STM32H747 M7-based Arduino board variants (GIGA R1, Portenta H7, Opta, Nicla Vision) to ArduinoCore-zephyr, including variant sources, Zephyr devicetree overlays, and per-board Kconfig fragments to enable required peripherals and pin mappings.

Changes:

• Introduces new STM32 variants with board-specific variant.{h,cpp}, overlays (.overlay), and Zephyr config (.conf) for Portenta H7, Opta, Nicla Vision, and GIGA R1.
• Adds “pure analog pin” wrappers for boards where some analog pins must not be used as digital pins.
• Adjusts SPI declarations by undefining SPI1..SPI8 in libraries/SPI/SPI.h to avoid macro collisions.

Reviewed changes

Copilot reviewed 32 out of 32 changed files in this pull request and generated 17 comments.

Show a summary per file

File	Description
variants/common/gpio_lowlevel_stm32.h	Adds STM32 low-level GPIO compatibility macros for Arduino-style APIs.
variants/arduino_portenta_h7_stm32h747xx_m7/variant.h	Defines Portenta variant pin constants and includes pure-analog handling.
variants/arduino_portenta_h7_stm32h747xx_m7/variant.cpp	Implements Portenta variant init and 1200-bps reset hook.
variants/arduino_portenta_h7_stm32h747xx_m7/skip_these_examples.txt	Variant-specific example exclusions for Portenta.
variants/arduino_portenta_h7_stm32h747xx_m7/pure_analog_pins.h	Portenta analog-only pin type wrapper.
variants/arduino_portenta_h7_stm32h747xx_m7/pure_analog_pins.cpp	Portenta analogRead overload for analog-only pins.
variants/arduino_portenta_h7_stm32h747xx_m7/known_example_issues.txt	Variant-specific known failing examples list for Portenta.
variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.overlay	Portenta devicetree overlay for peripherals/pins/partitions.
variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf	Portenta Zephyr config enabling required subsystems.
variants/arduino_opta_stm32h747xx_m7/variant.h	Adds Opta variant header stub.
variants/arduino_opta_stm32h747xx_m7/variant.cpp	Implements Opta 1200-bps reset hook.
variants/arduino_opta_stm32h747xx_m7/skip_these_examples.txt	Variant-specific example exclusions for Opta.
variants/arduino_opta_stm32h747xx_m7/known_example_issues.txt	Variant-specific known failing examples list for Opta.
variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.overlay	Opta devicetree overlay for peripherals/pins/partitions.
variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.conf	Opta Zephyr config enabling required subsystems.
variants/arduino_nicla_vision_stm32h747xx_m7/variant.h	Defines Nicla Vision variant constants and includes pure-analog handling.
variants/arduino_nicla_vision_stm32h747xx_m7/variant.cpp	Implements Nicla variant init and 1200-bps reset hook.
variants/arduino_nicla_vision_stm32h747xx_m7/skip_these_examples.txt	Variant-specific example exclusions for Nicla Vision.
variants/arduino_nicla_vision_stm32h747xx_m7/pure_analog_pins.h	Nicla Vision analog-only pin type wrapper.
variants/arduino_nicla_vision_stm32h747xx_m7/pure_analog_pins.cpp	Nicla Vision analogRead overload for analog-only pins.
variants/arduino_nicla_vision_stm32h747xx_m7/known_example_issues.txt	Variant-specific known failing examples list for Nicla Vision.
variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.overlay	Nicla Vision devicetree overlay for peripherals/pins/partitions.
variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.conf	Nicla Vision Zephyr config enabling required subsystems.
variants/arduino_giga_r1_stm32h747xx_m7/variant.h	Defines GIGA R1 variant constants and includes STM32 GPIO low-level header.
variants/arduino_giga_r1_stm32h747xx_m7/variant.cpp	Implements GIGA R1 1200-bps reset hook.
variants/arduino_giga_r1_stm32h747xx_m7/skip_these_examples.txt	Variant-specific example exclusions for GIGA R1.
variants/arduino_giga_r1_stm32h747xx_m7/pure_analog_pins.h	GIGA R1 analog-only pin type wrapper (A8–A11).
variants/arduino_giga_r1_stm32h747xx_m7/pure_analog_pins.cpp	GIGA R1 analogRead overload for analog-only pins.
variants/arduino_giga_r1_stm32h747xx_m7/known_example_issues.txt	Variant-specific known failing examples list for GIGA R1.
variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.overlay	GIGA R1 devicetree overlay for peripherals/pins/partitions.
variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.conf	GIGA R1 Zephyr config enabling required subsystems.
libraries/SPI/SPI.h	Avoids SPIx macro collisions by undefining SPI1..SPI8 before extern declarations.

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