cores: arduino: Bump to 0.53.1

[soburi]

Bump cores/arduino to https://github.com/arduino/ArduinoCore-zephyr @0.53.1.

Including following features:

Including the following features:

• Support for Serial USB
• Support for DAC
• ITOA implementation
• C++ language support (abi/new)
• Multithread support
• UART Improvements

All of these are new features, and there is no downgrading of existing functionality.
It would be better to improve the #ifdef isolation in main.cpp, but there are no problems with operation as it is.

[soburi]

@pillo79 @facchinm

I have one request: as these files do not include an SPDX identifier, could we explicitly assign a license to them?
Zephyr is quite finicky about this sort of thing...

cores/arduino/time_macros.h
cores/arduino/overloads.h
cores/arduino/new.h
loader/bootanimation.h
loader/llext_exports.c
loader/fixups.c
loader/matrix.inc

[pillo79]

Thank you SO MUCH for taking the time to do all of this. I always meant to start upstreaming but we've not at a stable point yet so it isn't easy to stop and look back.

We started using clang-format as a code formatting tool and that complicated this effort even more. But I see this PR is using Zephyr style, please tell me you didn't have to change all the formatting by hand? 👀
(I always meant to raise this in Discord to agree on a format and just use that. Would you like to propose something?)

Thanks for pointing out the files with missing licenses - will fix them ASAP.

Is cores/arduino now perfectly synced with 0.53? I could start experimenting with using ArduinoCore-zephyr as a proper Zephyr module in our loader build, separating the two in a much cleaner way.

Again thanks for the effort! 👏

[soburi]

We started using clang-format as a code formatting tool and that complicated this effort even more. But I see this PR is using Zephyr style, please tell me you didn't have to change all the formatting by hand? 👀 (I always meant to raise this in Discord to agree on a format and just use that. Would you like to propose something?)

I addressed only files that has diff here. I believe these gone into the Arduino style now.
IMO, after the merger, we'll also need to split up the all-in-one zephyrCommon.cpp.
So, this is a temporary issue, so I don't think it's something to worry about.
However, I'm concerned that the current .clang-format doesn't look very clean. We'll need to improve .clang-format with refer the zephyr's one and the rules a bit more.

Thanks for pointing out the files with missing licenses - will fix them ASAP.

This is beyond my control, so I appreciate your help. Also, I think the issue under libraries needs to be discussed as a separate issue.

Is cores/arduino now perfectly synced with 0.53? I could start experimenting with using ArduinoCore-zephyr as a proper Zephyr module in our loader build, separating the two in a much cleaner way.

With this patch series, there are almost no differences in core/arduino. However, there are a few patches that should be apply to arduino-repo from here. Since the loader build is independent, I don't think there's any problem with simply incorporating them, but I'll proceed with this in a separate PR.

[Copilot]

Pull request overview

This PR bumps the Arduino core for Zephyr from its current version to 0.53.1, bringing substantial new functionality and improvements to the Arduino API implementation on Zephyr RTOS.

Changes:

• Enhanced serial communication with USB CDC support, improved flow control, and better buffer management
• Added new Arduino-compatible APIs including C++ new/delete operators, itoa functions, and time macros
• Implemented DAC support alongside existing ADC/PWM capabilities with resolution control
• Introduced USB device stack integration with proper descriptor management and CDC ACM handling
• Improved code formatting and consistency across all files with standardized brace placement

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 19 comments.

Show a summary per file

File	Description
cores/arduino/zephyrSerial.h	Adds USB CDC support, availableForWrite method, flush implementation, and improved formatting
cores/arduino/zephyrSerial.cpp	Implements non-blocking write with yielding, flush mechanism, ring buffer reset on begin, and USB CDC integration
cores/arduino/zephyrPrint.h	Reformats code with consistent brace style and spacing
cores/arduino/zephyrPrint.cpp	Fixes spacing issues in operators and reformats for consistency
cores/arduino/zephyrCommon.cpp	Adds DAC support, analog resolution control, 64-bit cycle counter support, and guard conditions for empty GPIO configurations
cores/arduino/usb_device_descriptor.c	New file implementing USB device descriptors and configuration for the new USB stack
cores/arduino/time_macros.h	New file providing Arduino-compatible clock cycle conversion macros
cores/arduino/threads.cpp	New file implementing static thread initialization support
cores/arduino/overloads.h	New file declaring DAC and analog resolution getter functions
cores/arduino/new.h	New compatibility header redirecting to standard new header
cores/arduino/new.cpp	New file implementing C++ new/delete operators with malloc/free
cores/arduino/new	New standard header declaring C++ memory allocation operators
cores/arduino/main.cpp	Adds USB Serial initialization, static threads, variant initialization, and entry point for LLEXT
cores/arduino/itoa.cpp	New file implementing itoa/ltoa/utoa/ultoa conversion functions
cores/arduino/apiCommon.cpp	Reformats code for consistency
cores/arduino/abi.cpp	New file implementing ABI stubs for C++ runtime support
cores/arduino/USB.cpp	New file implementing USB CDC serial with baud rate change detection and device stack support
cores/arduino/SerialUSB.h	New header defining SerialUSB_ class for USB CDC communication
cores/arduino/CMakeLists.txt	Adds new source files USB.cpp, itoa.cpp, and threads.cpp to build
cores/arduino/Arduino.h	Adds DAC support, analog resolution APIs, USB serial header, helper macros for pin mapping
Kconfig	Adds USB device configuration options for manufacturer, product, VID, and PID

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