Add copyrights and improve example sketches

- Add Meta copyright headers to all files
- HelloExecuTorch: uses core ET runtime only (portable ops, no backend)
- KeywordSpotting: uses Cortex-M backend with CMSIS-NN accelerated ops
- Clarify the distinction in sketch comments

Author: psiddh

examples/arduino/ExecuTorchArduino.h

@@ -1,21 +1,21 @@
-#pragma once
+/*
+ * 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.
+ */
 
-// ExecuTorchArduino — ExecuTorch runtime for Arduino boards
-//
-// This header configures ExecuTorch for the Arduino build environment
-// and exposes the native ET C++ API. There is no wrapper — use
-// Program::load(), Method::execute(), etc. directly.
+#pragma once
 
 // Arduino's custom <new> header omits <exception>, which breaks
 // std::bad_variant_access in <variant>. Include it first.
 #include <exception>
 
-// ExecuTorch build configuration for Arduino
 #define C10_USING_CUSTOM_GENERATED_MACROS
 #define ET_ENABLE_DEPRECATED_CONSTANT_BUFFER 0
 #define FLATBUFFERS_MAX_ALIGNMENT 1024
 
-// Core runtime headers
 #include <executorch/runtime/platform/runtime.h>
 #include <executorch/runtime/executor/program.h>
 #include <executorch/runtime/executor/method.h>

examples/arduino/README.md

@@ -1,3 +1,11 @@
+<!---
+  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.
+--->
+
 # ExecuTorch Arduino Library
 
 Run PyTorch models on Arduino microcontrollers using ExecuTorch.

examples/arduino/build_arduino_library.sh

@@ -1,4 +1,10 @@
 #!/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.
+
 # build_arduino_library.sh — Assemble the ExecuTorch Arduino library
 # from sources in this repository.
 #

examples/arduino/examples/HelloExecuTorch/HelloExecuTorch.ino

@@ -1,19 +1,48 @@
+/*
+ * 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.
+ */
+
 // HelloExecuTorch — Minimal ExecuTorch sketch
 //
-// Initializes the ExecuTorch runtime and prints confirmation over Serial.
-// Use this to verify the library compiles and runs on your board before
-// loading a model.
+// Initializes the ExecuTorch runtime and loads a model using the core
+// ET library (portable ops only, no hardware-specific backends).
+// Use this to verify the library works on your board.
 
 #include <ExecuTorchArduino.h>
+#include "model.h"
+
+using executorch::extension::BufferDataLoader;
+using executorch::runtime::MemoryAllocator;
+using executorch::runtime::Program;
+using executorch::runtime::Result;
+
+alignas(16) static uint8_t arena[32 * 1024];
 
 void setup() {
   Serial.begin(115200);
   delay(2000);
 
-  Serial.println("=== ExecuTorch Arduino ===");
+  Serial.println("=== HelloExecuTorch ===");
 
   executorch::runtime::runtime_init();
   Serial.println("Runtime initialized.");
+
+  auto loader = BufferDataLoader(model_pte, model_pte_size);
+  Result<Program> program = Program::load(&loader);
+  if (program.ok()) {
+    Serial.println("Model loaded OK!");
+    Serial.print("  Size: ");
+    Serial.print(model_pte_size);
+    Serial.println(" bytes");
+    Serial.print("  Methods: ");
+    Serial.println(program->num_methods());
+  } else {
+    Serial.println("ERROR: Model load failed");
+  }
 }
 
 void loop() {

examples/arduino/examples/KeywordSpotting/KeywordSpotting.ino

@@ -1,20 +1,31 @@
-// KeywordSpotting — DS-CNN keyword spotting with ExecuTorch
+/*
+ * 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.
+ */
+
+// KeywordSpotting — DS-CNN inference with ExecuTorch + CMSIS-NN
 //
-// Runs a quantized DS-CNN model (MLPerf Tiny KWS benchmark) on hardcoded
-// MFCC test inputs and prints the detected keyword.  The model classifies
-// 12 keywords: silence, unknown, yes, no, up, down, left, right, on, off,
-// stop, go.
+// Runs a quantized DS-CNN model (MLPerf Tiny KWS benchmark) using the
+// Cortex-M backend with CMSIS-NN accelerated int8 ops.  The model
+// classifies 12 keywords: silence, unknown, yes, no, up, down, left,
+// right, on, off, stop, go.
 //
-// The model uses CMSIS-NN accelerated int8 ops on Cortex-M boards.
+// This example demonstrates:
+//   - Loading a .pte model with cortex_m::* ops (CMSIS-NN backend)
+//   - Setting up memory allocators for constrained devices
+//   - Running inference and reading output tensors
 //
-// Prerequisites:
-//   - model.h       : DS-CNN .pte exported with CortexMQuantizer, as a C array
-//   - test_inputs.h : MFCC features from real audio, as float arrays
+// Required files (not included, generate with export_model.py):
+//   - model.h       : DS-CNN .pte exported with CortexMQuantizer
+//   - test_inputs.h : MFCC features from real audio samples
 
 #include <ExecuTorchArduino.h>
 #include "model.h"
-#include "test_inputs.h"
 
+using executorch::aten::ScalarType;
 using executorch::extension::BufferDataLoader;
 using executorch::runtime::Error;
 using executorch::runtime::EValue;
@@ -40,9 +51,9 @@ void setup() {
   delay(2000);
 
   Serial.println("=== ExecuTorch Keyword Spotting ===");
-  Serial.print("Model size: ");
+  Serial.print("Model: ");
   Serial.print(model_pte_size);
-  Serial.println(" bytes");
+  Serial.println(" bytes (DS-CNN int8, CMSIS-NN)");
 
   executorch::runtime::runtime_init();
   Serial.println("Runtime initialized.");
@@ -60,16 +71,23 @@ void loop() {
   const char* method_name = nullptr;
   {
     auto r = program->get_method_name(0);
-    if (!r.ok()) { Serial.println("ERROR: no methods"); delay(5000); return; }
+    if (!r.ok()) {
+      Serial.println("ERROR: no methods");
+      delay(5000);
+      return;
+    }
     method_name = *r;
   }
 
   auto meta = program->method_meta(method_name);
-  if (!meta.ok()) { Serial.println("ERROR: method_meta"); delay(5000); return; }
+  if (!meta.ok()) {
+    Serial.println("ERROR: method_meta failed");
+    delay(5000);
+    return;
+  }
 
   MemoryAllocator method_allocator(sizeof(method_pool), method_pool);
 
-  // Allocate planned buffers
   size_t n_planned = meta->num_memory_planned_buffers();
   Span<uint8_t>* spans = static_cast<Span<uint8_t>*>(
       method_allocator.allocate(n_planned * sizeof(Span<uint8_t>)));
@@ -85,33 +103,34 @@ void loop() {
 
   auto method = program->load_method(method_name, &mm);
   if (!method.ok()) {
-    Serial.print("ERROR: load_method failed: 0x");
+    Serial.print("ERROR: load_method: 0x");
     Serial.println((int)method.error(), HEX);
     delay(5000);
     return;
   }
 
-  // Run inference
   Error status = method->execute();
   if (status != Error::Ok) {
-    Serial.print("ERROR: execute failed: 0x");
+    Serial.print("ERROR: execute: 0x");
     Serial.println((int)status, HEX);
     delay(5000);
     return;
   }
 
-  // Read output
   EValue output;
   method->get_outputs(&output, 1);
   if (output.isTensor()) {
     auto tensor = output.toTensor();
     int best = 0;
     float best_val = -1e9f;
     for (int i = 0; i < kNumClasses && i < tensor.numel(); i++) {
-      float val = (tensor.scalar_type() == executorch::aten::ScalarType::Float)
+      float val = (tensor.scalar_type() == ScalarType::Float)
           ? tensor.const_data_ptr<float>()[i]
           : static_cast<float>(tensor.const_data_ptr<int8_t>()[i]);
-      if (val > best_val) { best_val = val; best = i; }
+      if (val > best_val) {
+        best_val = val;
+        best = i;
+      }
     }
     Serial.print("Detected: ");
     Serial.println(kLabels[best]);

examples/arduino/library.properties

@@ -1,3 +1,9 @@
+# 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.
+
 name=ExecuTorchArduino
 version=0.1.0
 author=Meta Platforms

examples/arduino/platform_stubs.c

@@ -1,7 +1,14 @@
+/*
+ * 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.
+ */
+
 // Platform stubs for Arduino LLEXT environment.
 // These C library functions are not exported by the Zephyr kernel's
-// LLEXT symbol table but are referenced by the ExecuTorch runtime
-// and CMSIS-NN.
+// LLEXT symbol table but are referenced by the ExecuTorch runtime.
 
 #include <stdarg.h>
 #include <stdio.h>

zephyr/samples/hello-executorch/boards/arduino_uno_q.conf

@@ -1,3 +1,9 @@
+# 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.
+
 # Arduino Uno Q — STM32U585 (Cortex-M33, DSP, no MVE, no Ethos-U)
 # 2 MB flash, 786 KB SRAM — plenty of room for DS-CNN int8 (50 KB .pte).
 #