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commit a6cab8293d3fa1e1370f056d5e625ff7f95d4b48 Author: Afonso Oliveira <[email protected]> AuthorDate: Wed Sep 23 17:41:39 2026 +0100 Documentation/erbium: Add ET-Minion core diagram and references. Add the ET-Minion core diagram from the Erbium documentation (aifoundry-org/erbium, Apache-2.0) and a short description of the ET-Minion neighborhood, as suggested in review. Link the Erbium core, interrupt, memory map and UART documentation and ET-platform, and note that silicon uses a 10 MHz mtime while the emulator default is 2 MHz. Signed-off-by: Afonso Oliveira <[email protected]> --- .../erbium/boards/minion/erbium-minion-core.png | Bin 0 -> 83208 bytes .../risc-v/erbium/boards/minion/index.rst | 28 ++++++++++++++++++++- 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/Documentation/platforms/risc-v/erbium/boards/minion/erbium-minion-core.png b/Documentation/platforms/risc-v/erbium/boards/minion/erbium-minion-core.png new file mode 100644 index 00000000000..93bc885e576 Binary files /dev/null and b/Documentation/platforms/risc-v/erbium/boards/minion/erbium-minion-core.png differ diff --git a/Documentation/platforms/risc-v/erbium/boards/minion/index.rst b/Documentation/platforms/risc-v/erbium/boards/minion/index.rst index 6717a69de4e..4fd4a20d537 100644 --- a/Documentation/platforms/risc-v/erbium/boards/minion/index.rst +++ b/Documentation/platforms/risc-v/erbium/boards/minion/index.rst @@ -4,6 +4,19 @@ Erbium Minion .. tags:: chip:erbium, arch:risc-v, vendor:aifoundry +.. figure:: erbium-minion-core.png + :align: center + :alt: ET-Minion core block diagram + + ET-Minion core (source: `aifoundry-org/erbium + <https://github.com/aifoundry-org/erbium>`__, Apache-2.0). + +The Erbium CPU subsystem is one ET-Neighborhood of eight dual-threaded +RV64IMFC ET-Minion cores (16 harts), derived from the Esperanto ET-SoC-1, +together with a PLIC, a CLINT-style machine timer and a shared instruction +cache. Erbium silicon is not yet available, so this board targets the +``erbium_emu`` system emulator. NuttX runs on hart 0. + Memory and interrupts ===================== @@ -15,7 +28,10 @@ stack. The linker checks that the image and idle stack fit in MRAM. The PLIC at ``0xa0000000`` provides sources 1 through 6; UART0 uses source 3. Receive and transmit use interrupts, without periodic polling. The machine timer uses ``mtime`` at ``0x80f40200`` and ``mtimecmp`` at -``0x80f40208``. Its default frequency is 2 MHz in the emulator. +``0x80f40208``. ``CONFIG_ERBIUM_MTIMER_FREQ`` defaults to 2 MHz, the +emulator's timer rate. The Erbium documentation specifies a 10 MHz +``mtime`` (one tick every 100 ns) on silicon, so set this option to match +the target. Toolchain ========= @@ -138,3 +154,13 @@ for low-level console debugging. The emulator reads host input into its finite RX FIFO immediately. Feeding a long command through a pipe can overrun that FIFO. Automated console tests should pace input, for example by waiting for each echoed character. + +References +========== + +* `Erbium documentation <https://erbium.readthedocs.io/en/latest/>`_ +* `ET-Minion core <https://erbium.readthedocs.io/en/latest/minion/>`_ +* `Interrupts and PLIC source IDs <https://erbium.readthedocs.io/en/latest/interrupts/>`_ +* `CPU memory map <https://erbium.readthedocs.io/en/latest/cpu_mm/>`_ +* `UART <https://erbium.readthedocs.io/en/latest/uart/>`_ +* `ET-platform, including erbium_emu <https://github.com/aifoundry-org/et-platform>`_
