8770fbea0f
Adds a driver for the external QSPI PSRAM hanging off QMI chip select 1, such as the 8 MiB APS6404 fitted on the Pimoroni Pico Plus 2. rp23xx_psramconfig() assigns the CS1 pin, reads the device ID over the QMI direct interface to confirm an APS6404-family part (KGD 0x5D), resets it into quad mode and programs the QMI M1 timing/read/write formats so the region at 0x11000000 becomes directly addressable and writable. Because driving the QMI in direct mode stalls execute-in-place from the flash, the detection and (re)configuration code runs from RAM (.time_critical) with interrupts disabled; the command bytes are selected with immediates rather than a .rodata table for the same reason. The register values follow the Raspberry Pi Pico SDK setup_psram(). The detection routine only keeps the QMI DIRECT_CSR synchronization that is strictly necessary. Each candidate busy-wait was removed one at a time and re-verified on hardware: the post-enable "cooldown" waits, the READ_ID TXEMPTY wait (redundant with the BUSY wait after it), and a fixed nop delay proved unnecessary and are omitted. The three BUSY waits that remain -- after the quad-mode nudge, after each READ_ID byte, and after each reset/quad-enable command -- are required and carry a comment explaining that the frame must finish shifting before the chip select is deasserted, and what breaks otherwise (garbage ID reads, or the shared QMI bus wedging). rp23xx_psram_restore() re-applies the M1 configuration and is meant to be called from the flash write path, which goes through the bootrom and reconfigures the shared QMI for chip select 0. rp23xx_heaps.c is wired into the build and now uses the detected size, so the PSRAM is exposed to the memory manager (added to the main heap, used as a separate heap, or as the user heap) and is skipped cleanly when no PSRAM is present. Enabled by default on the pimoroni-pico-2-plus:nsh configuration, where it adds the 8 MiB to the main heap. A documentation page for the Pimoroni Pico Plus 2 is added alongside the other rp23xx boards, covering its serial console, LED, the external PSRAM and how it is exposed to the heap, the supported capabilities and the available configurations, with a photo of the board. Tested on Pimoroni Pico Plus 2 hardware: detection reports the 8 MiB APS6404, the region is read/write across its whole range (ramtest word, half-word and byte passes, marching/pattern/address-in-address), and the heap reports the extra 8 MiB. Assisted-by: Claude Code:claude-opus-4-8 Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com> |
||
|---|---|---|
| .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.