Summary: Add Initial support to pico2 (Arm Cortex M) #12518

psiddh · 2025-07-15T21:05:56Z

Test Plan:
1\ executorch/examples/rpi/build_firmware_pico.sh

2\ Flash the firmware

Hold BOOTSEL
Plug in Pico 2
Mounts as RPI-RP2
Copy executorch_pico.uf2 to that drive

3\ Check that LED light blinks 10 times (with 500 ms interval) , indicating that inference has been successful

Summary

[PLEASE REMOVE] See CONTRIBUTING.md's Pull Requests for ExecuTorch PR guidelines.

[PLEASE REMOVE] If this PR closes an issue, please add a Fixes #<issue-id> line.

[PLEASE REMOVE] If this PR introduces a fix or feature that should be the upcoming release notes, please add a "Release notes: " label. For a list of available release notes labels, check out CONTRIBUTING.md's Pull Requests.

Test plan

[PLEASE REMOVE] How did you test this PR? Please write down any manual commands you used and note down tests that you have written if applicable.

pytorch-bot · 2025-07-15T21:05:59Z

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/12518

📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

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github-actions · 2025-07-15T21:06:39Z

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backends/raspberry_pi/pico2/CMakeLists.txt

@@ -0,0 +1,40 @@
+cmake_minimum_required(VERSION 3.13)


backends/raspberry_pi/arm-cortex-m0plus-toolchain.cmake

+
+if(NOT DEFINED EXECUTORCH_BUILD_ARM_BAREMETAL)
+  # If not defined, assume we're building standalone
+  set(EXECUTORCH_BUILD_ARM_BAREMETAL ON)


backends/raspberry_pi/pico2/main.cpp

@@ -0,0 +1,129 @@
+#include "pico/stdio_usb.h"


backends/raspberry_pi/pico2/main.cpp

+  }
+}
+
+int main() {


backends/raspberry_pi/pico2/main.cpp

+#include <executorch/runtime/platform/runtime.h>
+
+// Declare your model data (from simple_addmodule_pte.c)
+extern const uint8_t model_pte[] __attribute__((aligned(8)));


digantdesai · 2025-07-21T11:25:27Z

backends/raspberry_pi/pico2/simple_addmodule_pte.c

@@ -0,0 +1,38 @@
+__attribute__((aligned(8))) const unsigned char model_pte[] = {


OK for now, but for the tutorial we should generate --> pte to pte.h --> include.

Added explicit comments in README on how to generate this header (also left comments in the file), This way Users can generate their own hex array and replace the contents

backends/raspberry_pi/syscall_stubs.c

+ * We are adding a custom syscall_stubs.c file to provide dummy implementations for syscalls that are not 
+ * available on the Pico platform. This is necessary because the Pico does not have an operating system, 
+ * and therefore does not support standard C library functions like _exit, _sbrk, _read, etc.
+ * By adding these stubs, we can resolve linker errors that occur when building our project for the Pico. 


backends/raspberry_pi/CMakeLists.txt

+include(${CMAKE_SOURCE_DIR}/tools/cmake/Codegen.cmake)
+
+target_sources(executorch_core PRIVATE ${CMAKE_CURRENT_LIST_DIR}/syscall_stubs.c)
+gen_selected_ops(LIB_NAME "portable_ops_lib" ROOT_OPS "aten::add.out")


digantdesai

Looks great. Esp how standalone this is from rest of the ExecuTorch. Does it make sense for it to live in https://github.com/pytorch-labs/executorch-examples

TBH we can land in executorch/examples, I was thinking long term if we want to build more around it.

CMakeLists.txt


 if(EXECUTORCH_BUILD_ARM_BAREMETAL)
  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backends/arm)
+  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/examples/arm/rp_pi)


CMakeLists.txt


 if(EXECUTORCH_BUILD_ARM_BAREMETAL)
  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backends/arm)
+  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/examples/arm/rp_pi)


examples/arm/rp_pi/README.md

+
+### (Pre-requisistes) Prepare the Environment for Arm
+1. See <a href="docs/source/backends-arm-ethos-u.md"/> for instructions on setting up the environment for Arm.
+2. Make sure you have the toolchain configured correctly.


examples/arm/rp_pi/arm-cortex-m0plus-toolchain.cmake

+if(NOT DEFINED EXECUTORCH_BUILD_ARM_BAREMETAL)
+  # If not defined, assume we're building standalone
+  set(EXECUTORCH_BUILD_ARM_BAREMETAL ON)
+endif()


examples/arm/rp_pi/pico2/CMakeLists.txt

+)
+add_compile_definitions(C10_USING_CUSTOM_GENERATED_MACROS)
+
+# Set correct flags for Pico (Cortex-M0+)


examples/arm/rp_pi/pico2/CMakeLists.txt

+    ${BAREMETAL_BUILD_DIR}/kernels/portable/libportable_ops_lib.a
+    -Wl,--no-whole-archive
+    ${BAREMETAL_BUILD_DIR}/kernels/portable/libportable_kernels.a
+    pico_stdlib


examples/arm/rp_pi/pico2/CMakeLists.txt

+#set(CMAKE_C_FLAGS "-Os -ffunction-sections -fdata-sections")
+set(CMAKE_EXE_LINKER_FLAGS "-Wl,--gc-sections")


examples/arm/rp_pi/pico2/main.cpp

+
+// Make sure blink_indicator is defined somewhere, or add a stub if not
+void blink_indicator(uint pin, int times, int delay_ms = 100) {
+    for (int i = 0; i < times; ++i) {


examples/arm/rp_pi/pico2/simple_addmodule_pte.c

@@ -0,0 +1,47 @@
+/* Copyright (c) Meta Platforms, Inc. and affiliates.


digantdesai · 2025-08-20T10:01:38Z

examples/arm/raspberry_pi/pico2/CMakeLists.txt

@@ -0,0 +1,59 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.


I do not remember what we agreed on for the home for this? Given we might also enable this for RISCv (not just arm)

moved to examples/rpi

digantdesai · 2025-08-20T10:02:17Z

examples/arm/raspberry_pi/pico2/simple_model_pte.c

@@ -0,0 +1,111 @@
+/* Copyright (c) Meta Platforms, Inc. and affiliates.


let'e generate the pte and use pte_to_header.py?

Yes , forgot to check-in in last iter, this is script: pte_to_array.py. Users can pass any model of their choice , this script converts the pte to hex array and bakes it into final pico2 firmware.

digantdesai · 2025-08-20T10:03:56Z

examples/arm/raspberry_pi/pico2/README.md

@@ -0,0 +1,86 @@
+## Overview


Too much code in the readme for my taste. Likey get outdated and broken soon. I would write a script and ask users to use that. If you want we can put that script in CI as well (until PTE generation and runner bin building)

Fixed README, all the steps now happens in this one single script : executorch/examples/rpi/build_firmware_pico.sh (forgot to add this script in the last iter)

digantdesai · 2025-08-20T10:05:51Z

examples/arm/raspberry_pi/pico2/main.cpp

+  float input_data_0[4] = {4.0, 109.0, 13.0, 123.0};
+  float input_data_1[4] = {9.0, 27.0, 11.0, 8.0};


can we take these from bundleio? And also verify the output?
And take input index from cmdline (optionally)?

There is no cmdline interface for pico2 (baremetal ). I

have added the validation step in this iter,.

bundleio is a great idea. Do you think we can add bundleio support as followup change to this ?

digantdesai

Thanks @psiddh. Looking much cleaner now. Left some more comments.

mergennachin · 2025-08-20T14:50:54Z

examples/arm/raspberry_pi/pico2/CMakeLists.txt

@@ -0,0 +1,59 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+# Copyright 2023-2025 Arm Limited and/or its affiliates.


why is this Copyright Arm? Did they contribute code this?

Fixed. (removed)

mergennachin · 2025-08-20T14:53:42Z

examples/arm/raspberry_pi/pico2/CMakeLists.txt

@@ -0,0 +1,59 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.


Agree, let's put in a dedicated raspberry pi folder under examples so that we can be flexible in the future

examples/rpi (or raspi)

mergennachin · 2025-08-20T14:59:36Z

examples/arm/raspberry_pi/pico2/simple_model_pte.h

@@ -0,0 +1,21 @@
+/* Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ * Copyright 2023-2025 Arm Limited and/or its affiliates.


examples/arm/raspberry_pi/pico2/simple_model_pte.c

Test Plan: 1 Build pico2 firmware executorch/examples/rpi/build_firmware_pico.sh 2. Flash the firmware : 'executorch_pico.uf2' 3. Verify that it successfully runs / infers the simple add module Reviewers: Subscribers: Tasks: Tags:

digantdesai

Let's try to address these comments before the branch cut?

digantdesai · 2025-09-08T16:41:09Z

examples/rpi/pico2/CMakeLists.txt

@@ -0,0 +1,143 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.


nit s/rpi/raspberrypi

digantdesai · 2025-09-08T16:41:42Z

examples/rpi/pte_to_array.py

@@ -0,0 +1,207 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.


use the one we already have from arm. if you want you can make it a devtools utils.

digantdesai · 2025-09-08T16:41:59Z

examples/rpi/build_firmware_pico.sh

+# build_firmware_pico.sh
+# Simple script to cross-compile ExecuTorch and build Pico2 firmware with optional model input
+
+set -e


Suggested change

set -e

set -eu

digantdesai · 2025-09-08T16:43:07Z

examples/rpi/build_firmware_pico.sh

+  cmake -B "${BUILD_DIR}" -DPICO_BOARD=pico2 -DINPUT_MODEL="./${DEFAULT_MODEL}" -DCMAKE_BUILD_TYPE=Release
+fi
+
+cmake --build "${BUILD_DIR}" -j$(nproc)


FWIW nproc won't work on a macos

digantdesai · 2025-09-08T16:43:47Z

examples/rpi/pico2/README.md

@@ -0,0 +1,45 @@
+# Overview


let's make a web doc as well? it can be same content. Add a picture or gif too :)

digantdesai · 2025-09-08T16:44:23Z

examples/rpi/pico2/model_pte.c

@@ -0,0 +1,18 @@
+/*


why do we need to check these model_pte.[ch] files in?

digantdesai · 2025-09-08T16:45:10Z

examples/rpi/pico2/main.cpp

+}
+
+void wait_for_usb() {
+  const int kMaxRetryCount = 10;


don't hardcode values, default args or consts may be? count as well as delay

digantdesai · 2025-09-08T16:45:27Z

examples/rpi/pico2/main.cpp

+  executorch::extension::BufferDataLoader loader(model_pte, model_pte_len);
+  auto program_result = Program::load(&loader);
+  if (!program_result.ok()) {
+    printf("Failed to load model: %d\n", (int)program_result.error());


use ET_LOG? Do we need any PAL changes?

digantdesai · 2025-09-08T16:46:43Z

examples/rpi/pico2/main.cpp

+  float input_data_0[4] = {4.0, 109.0, 13.0, 123.0};
+  float input_data_1[4] = {9.0, 27.0, 11.0, 8.0};


Use bundled IO. Hardcoding input doesn't work well with random PTEs.

digantdesai · 2025-09-08T16:47:18Z

examples/rpi/pico2/main.cpp

+    blink_indicator(INDICATOR_PIN_1, 10);
+    return false;
+  }
+  return true;


use bundle io and compare outputs

psiddh requested review from kirklandsign and larryliu0820 as code owners July 15, 2025 21:05

facebook-github-bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Jul 15, 2025

psiddh self-assigned this Jul 15, 2025

psiddh marked this pull request as draft July 15, 2025 21:07

psiddh mentioned this pull request Jul 15, 2025

Cross Compile Executorch for Arm Cortex M h/w (Raspberry PI Pico 2) and infer a simple model #11913

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larryliu0820 reviewed Jul 15, 2025

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@@ -0,0 +1,40 @@

cmake_minimum_required(VERSION 3.13)

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#include "pico/stdio_usb.h"

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}

}

int main() {

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Enable Pico2 support for ExecuTorch #13680

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Merge branch 'main' into pico2_poc

34cdc6b

psiddh merged commit cfd9b68 into main Sep 5, 2025
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		@@ -0,0 +1,38 @@
		__attribute__((aligned(8))) const unsigned char model_pte[] = {

		#set(CMAKE_C_FLAGS "-Os -ffunction-sections -fdata-sections")
		set(CMAKE_EXE_LINKER_FLAGS "-Wl,--gc-sections")

		@@ -0,0 +1,47 @@
		/* Copyright (c) Meta Platforms, Inc. and affiliates.

		@@ -0,0 +1,59 @@
		# Copyright (c) Meta Platforms, Inc. and affiliates.

		@@ -0,0 +1,111 @@
		/* Copyright (c) Meta Platforms, Inc. and affiliates.

		float input_data_0[4] = {4.0, 109.0, 13.0, 123.0};
		float input_data_1[4] = {9.0, 27.0, 11.0, 8.0};

		@@ -0,0 +1,143 @@
		# Copyright (c) Meta Platforms, Inc. and affiliates.

		@@ -0,0 +1,207 @@
		# Copyright (c) Meta Platforms, Inc. and affiliates.

Summary: Add Initial support to pico2 (Arm Cortex M) #12518

Summary: Add Initial support to pico2 (Arm Cortex M) #12518

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🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/12518

❌ 2 New Failures

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psiddh commented Jul 15, 2025 •

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