1686bb6c9e
Drives the speed of the four application cores. The rate is set to any of the operating points the vendor validates, all of which share a core voltage, so this touches no regulator. The cores run from the PLL being reprogrammed, so they park on a slower clock first, through a selector the vendor names as glitch free. While parked the PLL is stopped, given new dividers, restarted and watched until it locks; if it never locks the cores stay parked, since returning them to an unlocked PLL does not fail safely. Above a gigahertz the bus ratio must be two to one before the cores return: the bus fabric does not reach beyond about eight hundred megahertz. That is the one step in the sequence software cannot recover from, so the mux is moved before the ratio. The rate is measured rather than derived. The cores are counted against the crystal derived time counter and the result reported beside what the clock tree computes, because the manual and the vendor's code number the CPU PLL's outputs differently. The core selector's parent is cpupll_fout1, and the three CPU PLL outputs are marked CLK_GET_RATE_NOCACHE since this driver reprograms that PLL at run time. Assisted-by: Claude:claude-opus-5 Signed-off-by: Justin Hammond <justin@dynam.ac> |
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| dummy | ||
| fs | ||
| graphics | ||
| include | ||
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| net | ||
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| pass1 | ||
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| AUTHORS | ||
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| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
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| LICENSE | ||
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| 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.