[Controller] Added board config for custom controller STeMCell (updated)

[sadekbaroudi]

Description

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[sadekbaroudi]

This pull request is based on the previous pull request by @Mariappan ( #16287 )

I have updated it to latest develop, and added a commit to support the changes to pindefs. I have tested on a few fingerpunch keyboards using the stemcell.

[keyboard-magpie]

I have been using this with a stemcell for the last week, without issue. RGB features and i2c pointing device included. EEPROM features appear to be working appropriately although have not tested VIA only lighting options.

The PR, I believe, addresses all the issues raised in the "stuck" PR #16287 , but I am unsure of the etiquette surrounding merging this ahead of the stuck PR.

[sadekbaroudi]

Oh, just to explicitly note, some of the objections in the last PR were addressed by creating this feature: #16598

I am also leveraging this so we don't need to use the STMC=yes and can instead use the standardized CONVERT_TO=stemcell

[zvecr]

Some of the changes still fall under the same issues as #17711, where specifying the full board/chibos config files wants to be avoided.

For EEPROM, it would be to avoid STEMCELL_tinyuf2 linker script and be solved more generically for BOOTLOADER = tinyuf2

[zvecr]

This doesnt belong in pin defs

Suggested change

	# ifndef SERIAL_USART_DRIVER
	# define SERIAL_USART_DRIVER SD2
	# endif

[zvecr]

This doesnt belong in pin defs

Suggested change

	#define I2C1_SCL_PIN D0
	#define I2C1_SDA_PIN D1
	#define FEE_PAGE_BASE_ADDRESS 0x08008000

[sadekbaroudi]

Some of the changes still fall under the same issues as #17711, where specifying the full board/chibos config files wants to be avoided.

For EEPROM, it would be to avoid STEMCELL_tinyuf2 linker script and be solved more generically for BOOTLOADER = tinyuf2

For reference, I assume this conversation is relevant, so linking it here:
#16287 (comment)

I don't know enough about how this part of the codebase works, so deferring to @Mariappan to chime in.

As a side note, I'm happy to contribute and/or fix myself, but some more detailed guidance would be very helpful!

[sigprof]

The EEPROM emulation should work with BOOTLOADER = tinyuf2 if you use

EEPROM_DRIVER = wear_leveling
WEAR_LEVELING_DRIVER = legacy

(WEAR_LEVELING_DRIVER = embedded_flash currently does not support F4x1 chips.)

STEMCELL_tinyuf2.ld does not seem to be needed — it's effectively the same as STM32F401xC_tinyuf2.ld (and if the real chip is F411, the RAM size is wrong), except it also defines flash regions for the bootloader and EEPROM backing store, but those regions are not actually used anywhere.

Board config should be inherited from a ChibiOS definition, like in GENERIC_STM32_F411XE; the only problem is mcuconf.h, which is also copied in full in existing converters like QMK_PM2040, so this one may need to remain as is for now.

[sadekbaroudi]

@Mariappan has started working on #16287 again, so I'll stop using this PR, and defer to that one. If it's okay, I'll keep this one open until that one gets merged in. But for now, this one is on pause.

Please let me know if anyone has any objections to this.

[zvecr]

replaced by #16287