Summary: Add Initial support to pico2 (Arm Cortex M)

examples/rpi/build_firmware_pico.sh

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+#!/bin/bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+#!/bin/bash
+# build_firmware_pico.sh
+# Simple script to cross-compile ExecuTorch and build Pico2 firmware with optional model input
+
+set -e
+
+# Paths
+ROOT_DIR="$(cd "$(dirname "$0")/../.." && pwd)"  # examples/rpi/ -> root dir
+PICO2_DIR="${ROOT_DIR}/examples/rpi/pico2"
+BUILD_DIR="${PICO2_DIR}/build"
+EXECUTORCH_BUILD_DIR="${ROOT_DIR}/cmake-out"
+
+# Default model
+DEFAULT_MODEL="default_model.pte"
+
+usage() {
+  echo "Usage: $0 [--clean] [--model=path/to/model.pte]"
+  echo "  --clean           Clean build directories"
+  echo "  --model=FILE      Specify model file to embed (relative to pico2/)"
+  exit 1
+}
+
+# Parse args
+MODEL_INPUT=""
+CLEAN_BUILD=0
+
+for arg in "$@"; do
+  case $arg in
+    --clean)
+      CLEAN_BUILD=1
+      shift
+      ;;
+    --model=*)
+      MODEL_INPUT="${arg#*=}"
+      shift
+      ;;
+    *)
+      usage
+      ;;
+  esac
+done
+
+# Clean if requested
+if [ $CLEAN_BUILD -eq 1 ]; then
+  echo "Cleaning build directories..."
+  rm -rf "${EXECUTORCH_BUILD_DIR}" "${BUILD_DIR}"
+  echo "Clean complete."
+  exit 0
+fi
+
+# Step 1: Cross compile ExecuTorch from root dir
+echo "Cross compiling ExecuTorch baremetal ARM..."
+
+cmake -B "${EXECUTORCH_BUILD_DIR}" \
+  -DCMAKE_TOOLCHAIN_FILE="${ROOT_DIR}/examples/arm/ethos-u-setup/arm-none-eabi-gcc.cmake" \
+  -DTARGET_CPU=cortex-m0plus \
+  -DEXECUTORCH_BUILD_ARM_BAREMETAL=ON \
+  -DEXECUTORCH_PAL_DEFAULT=minimal \
+  -DEXECUTORCH_DTYPE_SELECTIVE_BUILD=ON \
+  -DCMAKE_BUILD_TYPE=MinSizeRel \
+  -DEXECUTORCH_ENABLE_LOGGING=OFF \
+  -DEXECUTORCH_SELECT_ALL_OPS=OFF \
+  -DEXECUTORCH_BUILD_EXECUTOR_RUNNER=OFF \
+  -DCMAKE_INSTALL_PREFIX="${EXECUTORCH_BUILD_DIR}" \
+  "${ROOT_DIR}"
+
+cmake --build "${EXECUTORCH_BUILD_DIR}" --target install -j$(nproc)
+
+echo "ExecuTorch cross compile complete."
+
+# Step 2: Build firmware for Pico2 with model input
+
+cd "${PICO2_DIR}"
+
+if [ -n "$MODEL_INPUT" ]; then
+  # Use specified model
+  if [ ! -f "${MODEL_INPUT}" ]; then
+    echo "Error: Specified model file '${MODEL_INPUT}' not found in pico2 directory."
+    exit 1
+  fi
+  echo "Building firmware with model: ${MODEL_INPUT}"
+  cmake -B "${BUILD_DIR}" -DPICO_BOARD=pico2 -DINPUT_MODEL="./${MODEL_INPUT}" -DCMAKE_BUILD_TYPE=Release
+else
+  # Use default model
+  echo "Building firmware with default model: ${DEFAULT_MODEL}"
+  cmake -B "${BUILD_DIR}" -DPICO_BOARD=pico2 -DINPUT_MODEL="./${DEFAULT_MODEL}" -DCMAKE_BUILD_TYPE=Release
+fi
+
+cmake --build "${BUILD_DIR}" -j$(nproc)
+
+echo "Firmware build complete. Output in ${BUILD_DIR}, Binary: executorch_pico.uf2"

examples/rpi/pico2/CMakeLists.txt

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+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the LICENSE
+# file in the root directory of this source tree.
+
+cmake_minimum_required(VERSION 3.13)
+
+# Include FetchContent for Pico SDK
+include(FetchContent)
+
+FetchContent_Declare(
+  pico_sdk
+  GIT_REPOSITORY https://github.com/raspberrypi/pico-sdk.git
+  GIT_TAG 2.0.0
+)
+
+FetchContent_MakeAvailable(pico_sdk)
+set(PICO_SDK_PATH ${pico_sdk_SOURCE_DIR})
+include(${PICO_SDK_PATH}/pico_sdk_init.cmake)
+
+project(executorch_pico C CXX ASM)
+pico_sdk_init()
+
+set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../../..)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Configure input model file
+set(INPUT_MODEL
+    "default_model.pte"
+    CACHE STRING "Input PTE model file to embed"
+)
+
+# Convert relative paths to absolute
+if(NOT IS_ABSOLUTE "${INPUT_MODEL}")
+  set(INPUT_MODEL "${CMAKE_CURRENT_SOURCE_DIR}/${INPUT_MODEL}")
+endif()
+
+message(STATUS "Using model file: ${INPUT_MODEL}")
+
+# Validate model file exists
+if(NOT EXISTS "${INPUT_MODEL}")
+  message(FATAL_ERROR "Model file '${INPUT_MODEL}' does not exist.")
+endif()
+
+# Create model_pte.c if it doesn't exist
+set(MODEL_PTE_C "${CMAKE_CURRENT_SOURCE_DIR}/model_pte.c")
+if(NOT EXISTS "${MODEL_PTE_C}")
+  file(
+    WRITE "${MODEL_PTE_C}"
+    "#include \"model_pte.h\"\n"
+    "\n"
+    "const uint8_t model_pte[] __attribute__((aligned(8))) = {\n"
+    "    // Model data will be injected here\n"
+    "};\n"
+    "\n"
+    "const unsigned int model_pte_len = sizeof(model_pte);\n"
+  )
+  message(STATUS "Created initial model_pte.c")
+endif()
+
+# Use a stamp file instead of declaring model_pte.c as OUTPUT
+set(MODEL_STAMP "${CMAKE_CURRENT_BINARY_DIR}/model_pte.stamp")
+
+add_custom_command(
+  OUTPUT ${MODEL_STAMP}
+  COMMAND python3 ${EXECUTORCH_ROOT}/executorch/examples/rpi/pte_to_array.py
+          --model ${INPUT_MODEL} --file ${MODEL_PTE_C}
+  COMMAND ${CMAKE_COMMAND} -E touch ${MODEL_STAMP}
+  DEPENDS ${INPUT_MODEL}
+          ${EXECUTORCH_ROOT}/executorch/examples/rpi/pte_to_array.py
+  COMMENT "Injecting PTE data from '${INPUT_MODEL}' into model_pte.c"
+  VERBATIM
+)
+
+# Target to ensure model injection happens
+add_custom_target(inject_model_data ALL DEPENDS ${MODEL_STAMP})
+
+# Check if source files exist
+if(NOT EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/main.cpp")
+  message(FATAL_ERROR "main.cpp not found in ${CMAKE_CURRENT_SOURCE_DIR}")
+endif()
+
+# Create the executable
+add_executable(
+  executorch_pico main.cpp ${MODEL_PTE_C} # Use the full path to be explicit
+)
+
+# Ensure model data is injected before building
+add_dependencies(executorch_pico inject_model_data)
+
+# Set correct target properties for Pico2/RP2350
+set_target_properties(
+  executorch_pico PROPERTIES SUFFIX ".elf" OUTPUT_NAME "executorch_pico"
+)
+
+# Configure Pico-specific settings
+pico_enable_stdio_usb(executorch_pico 1)
+pico_enable_stdio_uart(executorch_pico 0)
+
+# Set correct flags for Pico2 (RP2350)
+target_compile_options(
+  executorch_pico PRIVATE -mcpu=cortex-m33 -mfloat-abi=soft -mthumb
+)
+
+target_include_directories(
+  executorch_pico
+  PRIVATE ${EXECUTORCH_ROOT} ${EXECUTORCH_ROOT}/executorch/third-party
+          ${EXECUTORCH_ROOT}/executorch/runtime/core/portable_type/c10
+)
+
+target_compile_definitions(
+  executorch_pico
+  PRIVATE C10_USING_CUSTOM_GENERATED_MACROS EXECUTORCH_ENABLE_LOGGING=OFF
+          EXECUTORCH_PAL_DEFAULT=minimal
+)
+
+# Optimization flags
+target_compile_options(
+  executorch_pico PRIVATE -Os -ffunction-sections -fdata-sections
+)
+
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--gc-sections")
+
+set(BAREMETAL_BUILD_DIR ${EXECUTORCH_ROOT}/executorch/cmake-out/)
+
+# Link ExecuTorch and Pico libraries
+target_link_libraries(
+  executorch_pico
+  PRIVATE ${BAREMETAL_BUILD_DIR}/lib/libexecutorch.a
+          ${BAREMETAL_BUILD_DIR}/lib/libexecutorch_core.a
+          -Wl,--whole-archive
+          ${BAREMETAL_BUILD_DIR}/lib/libportable_ops_lib.a
+          -Wl,--no-whole-archive
+          ${BAREMETAL_BUILD_DIR}/lib/libportable_kernels.a
+          pico_stdlib
+          pico_stdio_usb
+)
+
+# Only add extra outputs if the target builds successfully
+if(TARGET executorch_pico)
+  pico_add_extra_outputs(executorch_pico)
+endif()

examples/rpi/pico2/README.md

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+# Overview
+This document outlines the steps required to run a simple Add Module on the Pico2 microcontroller using executorch.
+
+## (Pre-requisistes) Prepare the Environment for Arm
+1. See <a href="https://docs.pytorch.org/executorch/main/tutorial-arm.html#set-up-the-developer-environment"/> for instructions on setting up the environment for Arm.
+2. Make sure you have the toolchain configured correctly.
+```bash
+which arm-none-eabi-gcc
+--> return something like executorch/examples/arm/ethos-u-scratch/arm-gnu-toolchain-13.3.rel1-x86_64-arm-none-eabi/bin/arm-none-eabi-gcc
+```
+
+## Build Pico2 Firmware with Executorch
+
+This step involves two sub steps
+
+1. Cross Compile Executorch for Arm Cortex M, Pico2 target
+2. Build the firmware with the input model provided (If not provided, it will use the default_model.pte)
+
+Use the following command to build the firmware:
+``` bash
+executorch/examples/rpi/build_firmware_pico.sh --model=<path_to_model.pte>
+```
+
+### Flash Firmware
+Hold the BOOTSEL button on the Pico2 and connect it to your computer; it will mount as RPI-RP2. Copy the executorch_pico.uf2 file to this drive.
+
+### Verify Execution
+Check that the Pico2's LED blinks 10 times at 500 ms interval to confirm successful firmware execution.
+The Pico2's LED should blink 10 times at 500 ms intervals, indicating successful firmware execution. If connected via serial, you should see:
+
+```bash
+Method loaded [forward]
+Output: 13.000000, 136.000000, 24.000000, 131.000000
+```
+
+### Debugging via Serial Terminal
+On macOS or Linux, open a serial terminal with:
+```bash
+screen /dev/tty.usbmodem1101 115200
+```
+
+Replace /dev/tty.usbmodem1101 with your device path. This terminal shows program logs and errors. If
+the LED blinks 10 times at 100 ms intervals, your program hit an error state—check the logs here.
+
+These steps complete running the simple model on Pico2 using ExecuTorch.