jsanchez-2g opened a new pull request, #19904:
URL: https://github.com/apache/nuttx/pull/19904
## Summary
Fix HSI48 and clock recovery system configuration required for crystal-less
USB
device operation on STM32F0 and STM32L0.
The fixes:
- Enable the CRS peripheral clock whenever HSI48 is in use, while retaining
support for boards that explicitly select CONFIG_STM32_CRS.
- Enable the CRS frequency error counter together with automatic trimming.
- Enable the SYSCFG clock when VREFINT is enabled on STM32L0.
- Write SYSCFG_CFGR3 after setting ENBUFVREFINTHSI48; previously the HSI48
voltage-reference bit was updated only in a local variable.
- Select USB SOF as the CRS synchronization source for NUCLEO-L073RZ.
Before these changes, USB device registers could appear correctly configured,
and the host could detect the D+ pull-up, but the 48 MHz clock was not
usable:
the controller did not latch USB reset in USB_ISTR and never raised its USB
interrupt.
## Impact
- New feature added: NO. Bug fixes only.
- User adaptation required: NO.
- Build impact: NO.
- Hardware impact: YES. STM32F0, STM32L0, and the shared HSI48 M0 helper,
which also supports STM32U0.
- Documentation update required: NO. Board configuration documentation is
included with the corresponding board-support PRs.
- Security impact: NO.
- Compatibility impact: Existing HSI48 users retain their selected behavior;
the CRS is now correctly enabled and able to trim the oscillator.
## Testing
Build host:
- Linux 6.18.33.2-microsoft-standard-WSL2
- arm-none-eabi-gcc 13.2.1
Hardware:
- ST NUCLEO-F072RB
- ST NUCLEO-L073RZ
Before:
- On NUCLEO-L073RZ, SYSCFG_CFGR3 read 0x00000000 because SYSCFG was
unclocked. USB_ISTR never latched host reset, and USB IRQ 47 never fired.
- Both board USB-device configurations failed enumeration when tested from
pristine apache/master plus board support.
After:
- NUCLEO-L073RZ: SYSCFG_CFGR3 enables VREFINT and the HSI48 reference;
CRS_CR enables CEN and AUTOTRIMEN; NSH and USB CDC/ACM enumeration pass.
- NUCLEO-F072RB: NSH and USB CDC/ACM enumeration pass.
- Both results were reproduced from a clean upstream NuttX plus upstream
NuttX Apps checkout after the signed histories were rebuilt.
Validation:
- ./tools/checkpatch.sh -g apache/master...usb/hsi48-crs-standalone
- File-mode checkpatch passed for all changed files.
- Real hardware build, flash, NSH, and enumeration tests passed on both
boards.
## PR verification Self-Check
- [x] This PR introduces one functional area: HSI48/CRS clock recovery fixes.
- [x] All commits include a description, Signed-off-by, and Assisted-by
trailers.
- [x] Source passes checkpatch.
- [x] Real hardware build and runtime testing was completed.
- [x] This PR is ready for review.
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