16e3c8c6de
The SYSCFG peripheral clock was gated on CONFIG_STM32_SYSCFG, but that symbol is not defined by the STM32L0 Kconfig (only stm32h7 declares it), so RCC_APB2ENR_SYSCFGEN was never set on this chip. With SYSCFG unclocked every write performed by vrefint_enable() is discarded and SYSCFG_CFGR3 reads back as 0x00000000. VREFINT and, in particular, the ENBUFVREFINTHSI48 reference for the HSI48 oscillator are therefore never enabled. HSI48 still reports HSI48RDY, but it runs without its voltage reference and the 48MHz clock supplied to the USB device controller is unusable: the controller cannot sample the bus, never latches a reset condition in USB_ISTR, and never raises its interrupt. The result is a USB device that is configured correctly in every visible register yet never enumerates. VREFINT is configured exclusively through SYSCFG_CFGR3, so enable the SYSCFG clock whenever CONFIG_STM32_VREFINT is selected. Observed on NUCLEO-L073RZ (STM32L073RZ): before: SYSCFG_CFGR3 = 0x00000000, no enumeration after: SYSCFG_CFGR3 non-zero, device enumerates as CDC/ACM Assisted-by: GitHub Copilot:claude-opus-5 Signed-off-by: jsanchez-2g <jsanchez@2g-eng.com> |
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| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.