Why Compilation Is Slow in Arduino IDE for ESP32 Projects
Complex ESP32 Framework:
The ESP32 platform (via the esp32 core by Espressif) includes a large codebase with support for Wi-Fi, Bluetooth, FreeRTOS, and peripherals. Compiling this framework, especially with libraries like BLEMidi, requires significant processing, as it involves compiling many source files and linking them.
Library Dependencies:
Libraries like Arduino-BLE-MIDI add additional code that must be compiled. If the library includes many source files or dependencies, it increases compilation time.
Verbose Compilation Output:
The Arduino IDE’s default settings enable verbose output during compilation, which can slow down the process slightly due to the overhead of printing detailed logs to the console.
Hardware Limitations:
If your computer has limited CPU power, low RAM, or a slow storage drive (e.g., HDD instead of SSD), compilation times can increase significantly.
Incremental Compilation Limitations:
The Arduino IDE does not always optimize incremental builds effectively. Even small code changes may trigger a full recompilation of the sketch and libraries, especially for ESP32 projects.
Preprocessor and Header Files:
The Arduino IDE preprocesses .ino files, converting them to valid C++ and including necessary headers. This process, combined with complex header dependencies in libraries, can add overhead.
Optimization Settings:
The default optimization level for ESP32 in the Arduino IDE (-Os for size optimization) can sometimes lead to longer compilation times compared to other settings, as the compiler works to minimize the binary size.
Ways to Improve Compilation Speed in Arduino IDE
Here are practical steps to reduce compilation times for your ESP32 project:
1. Upgrade Your Hardware
Use an SSD: If you’re using a hard disk drive (HDD), switching to a solid-state drive (SSD) can significantly reduce file access times during compilation.
Increase RAM: Ensure your computer has at least 8GB of RAM (16GB or more is ideal) to handle the memory demands of compiling large projects.
Faster CPU: A multi-core CPU with higher clock speeds will speed up compilation. If you’re using an older or low-power CPU, consider upgrading.
2. Optimize Arduino IDE Settings
Disable Verbose Output:
Go to File > Preferences in the Arduino IDE.
Uncheck Show verbose output during: Compilation (leave Upload checked if you want upload details).
This reduces the time spent writing logs to the console, though it won’t affect the actual compilation process significantly.
Enable Parallel Compilation:
In File > Preferences, check if there’s an option to enable parallel compilation (available in Arduino IDE 2.x). This allows the IDE to use multiple CPU cores, speeding up the process.
Alternatively, add the following to your platform.txt file (located in the ESP32 core folder, e.g., ~/.arduino15/packages/esp32/hardware/esp32/2.x.x/platform.txt):
textcompiler.c.extra_flags=-j
compiler.cpp.extra_flags=-j
This enables parallel compilation explicitly.
3. Use Arduino IDE 2.x
The Arduino IDE 2.x is faster than the older 1.x versions due to its modernized build system and better integration with the ESP32 core.
Action: If you’re using Arduino IDE 1.x (e.g., 1.8.x), download and switch to Arduino IDE 2.x from the Arduino website. It’s available for Windows, macOS, and Linux and offers improved performance and features like better code completion.
4. Optimize Your Code and Libraries
Minimize Library Usage:
Review the Arduino-BLE-MIDI library and ensure you’re using the latest version from GitHub. Older versions may include unnecessary code.
If possible, remove unused library features or functions by commenting out or excluding parts of the library not needed for your project (requires modifying the library source, so proceed with caution).
Reduce Code Size:
Avoid unnecessary includes or large data structures. In your code, the Player_Data array (byte Player_Data[MAX_DIVISIONS][MAX_NOTES_PER_DIV][3]) is relatively large (64 × 2 × 3 = 384 bytes). If you can reduce MAX_DIVISIONS or MAX_NOTES_PER_DIV without affecting functionality, it may slightly reduce compilation time.
Use Conditional Compilation:
Wrap debug code in #ifdef directives to exclude it from release builds:
cpp#define DEBUG 1
#if DEBUG
void manage_Serial_Out_Display() {
// Debug code here
}
#endif
Set IsDebugging = false and disable debug-related code to reduce compilation overhead.
5. Switch to PlatformIO
Why: PlatformIO, an alternative to the Arduino IDE, offers a more efficient build system with better incremental compilation, dependency management, and support for parallel builds. It’s particularly effective for ESP32 projects.
How to Switch:
Install Visual Studio Code (VS Code) from code.visualstudio.com.
Install the PlatformIO extension in VS Code.
Create a new PlatformIO project, selecting the ESP32 DevKitC4 board.
Copy your sketch (.ino file) into the src folder of the PlatformIO project and convert it to a .cpp file (rename it, e.g., main.cpp).
Add the Arduino-BLE-MIDI library to your project by including it in the platformio.ini file:
ini[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps = lathoub/Arduino-BLE-MIDI
Build and upload the project from PlatformIO.
Benefits:
PlatformIO caches compiled objects, making subsequent builds much faster.
It supports multi-core compilation by default.
It provides better dependency resolution, avoiding redundant compilations.
6. Adjust ESP32 Build Settings
Change Optimization Level:
In the Arduino IDE, the default optimization is -Os (optimize for size). Switching to -O2 (optimize for speed) can sometimes reduce compilation time at the cost of larger binary size.
Edit the platform.txt file for the ESP32 core (e.g., ~/.arduino15/packages/esp32/hardware/esp32/2.x.x/platform.txt) and change:
textcompiler.c.flags=-Os …
compiler.cpp.flags=-Os …
to:
textcompiler.c.flags=-O2 …
compiler.cpp.flags=-O2 …
Be cautious, as this may increase the binary size and could affect memory usage on the ESP32.
Disable Unused Features:
If your project doesn’t use Wi-Fi, disable it in the ESP32 core by setting psram or other features to minimal settings in platformio.ini (for PlatformIO) or by modifying the build configuration. This requires advanced knowledge of the ESP32 framework.
7. Clean the Build Cache
Sometimes, the Arduino IDE’s build cache becomes corrupted or bloated, leading to longer compilation times.
Action:
In Arduino IDE, go to File > Preferences and note the “Sketchbook location.”
Navigate to that folder and delete the build or temporary folders (e.g., ~/.arduino15/packages/esp32/hardware/esp32/2.x.x/build).
Rebuild your project. This forces a clean compile, which may resolve issues with stale cache files.
8. Use a Faster Compiler Toolchain
The ESP32 core uses the xtensa-esp32-elf-gcc compiler. Ensure you’re using the latest version of the ESP32 core (check in Boards Manager for updates to “esp32” by Espressif Systems).
PlatformIO allows you to experiment with different toolchain versions, which may offer performance improvements.
9. Test with a Minimal Sketch
To isolate whether the issue is with your code or the environment, compile a minimal ESP32 sketch:
cpp#include
void setup() {
Serial.begin(115200);
}
void loop() {
Serial.println(“Test”);
delay(1000);
}
If this compiles quickly, the issue is likely related to your code or the Arduino-BLE-MIDI library. If it’s still slow, the problem lies in your IDE setup or hardware.
Expected Compilation Time
On a modern computer (e.g., quad-core CPU, 16GB RAM, SSD), a typical ESP32 sketch with a few libraries should take 10–30 seconds to compile.
Your project, with the Arduino-BLE-MIDI library and a moderately complex sketch, might take 30–60 seconds on average.
If compilation takes several minutes, it’s likely due to one of the factors above (e.g., slow hardware, verbose output, or inefficient build system).
Recommendations for Your Specific Case
Given your ESP32 project with the Arduino-BLE-MIDI library:
Switch to Arduino IDE 2.x: This is the easiest way to improve compilation speed without changing your workflow significantly.
Try PlatformIO: If you’re comfortable with VS Code, PlatformIO will likely cut compilation times in half due to its caching and parallel build capabilities.
Disable Verbose Output: This will make the process feel faster by reducing console output.
Check Hardware: If you’re using an older computer or HDD, consider upgrading to an SSD or a faster machine.
Update ESP32 Core and Library:
In Arduino IDE, go to Tools > Board > Boards Manager, search for “esp32,” and ensure you have the latest version (e.g., 2.x.x or higher).
Check for updates to the Arduino-BLE-MIDI library via the Library Manager or GitHub.
Test Compilation Time: After applying these changes, time the compilation of your sketch (e.g., use a stopwatch or check the IDE’s status bar). If it’s still slow (>60 seconds), share the exact time and your computer specs (CPU, RAM, storage type) for further diagnosis.
Example Workflow with PlatformIO
If you decide to try PlatformIO:
Install VS Code and the PlatformIO extension.
Create a new project for the ESP32 DevKitC4.
Replace the default main.cpp with your corrected sketch (from my previous response).
Add the Arduino-BLE-MIDI library to platformio.ini:
ini[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps = lathoub/Arduino-BLE-MIDI
Build the project using the PlatformIO toolbar in VS Code. The first build may take 30–60 seconds, but subsequent builds should be faster (10–20 seconds) due to caching.
If Issues Persist
Share More Details: Provide your computer specs (CPU, RAM, HDD/SSD), Arduino IDE version, ESP32 core version, and the exact compilation time (in seconds).
Check for Errors: If compilation fails or produces warnings, share them to identify potential issues.
Profile the Build: If you’re using PlatformIO, enable verbose mode (pio run -v) to see which step takes the most time (e.g., compiling specific library files).