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Csound runs on various embedded platforms, enabling standalone audio devices and hardware instruments.

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Bela

Bela is a low-latency audio platform for embedded audio applications, running on BeagleBone boards.

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Requirements

  • Bela board (BeagleBone-based)
  • Cross-compilation toolchain for armhf
  • Xenomai (real-time extensions)

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Two deployment options

Csound for Bela is provided in two forms:
  1. BelaCsound.cpp: C++ functions (setup(), render(), cleanup()) for Bela C++ projects, requiring linking to the Csound library
  2. belacsound: Standalone executable built with CMake using -DBUILD_BELA=1

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Build on Bela board

Building directly on the Bela board as root: 
# Copy custom configuration
cp Bela/Custom.cmake.bela-<your-version> Custom.cmake

# Configure and build
mkdir build && cd build
cmake .. -DBUILD_BELA=1 -DUSE_DOUBLE=0 \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_INSTALL_PREFIX=/usr/ \
  -DCMAKE_CXX_FLAGS="-Werror=unused-command-line-argument" \
  -DCMAKE_C_FLAGS="-Werror=unused-command-line-argument"

make && make install
sudo ldconfig
If CMake fails finding headers, re-run with --debug-trycompile.

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Cross-compilation setup

For cross-compiling from a Linux host:

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Step 1: Install toolchain

On Debian/Ubuntu: 
sudo apt-get install arm-linux-gnueabihf-g++ \
  crossbuild-essential-armhf \
  libsndfile1-dev:armhf \
  libasound-dev:armhf

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Step 2: Build Xenomai for armhf

Follow Xenomai documentation to build for ARM architecture.

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Step 3: Build Bela libraries

Build libbela and libbelaextra for armhf. The crosscompile-setup.sh script can guide you through this process.

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Step 4: Cross-compile Csound

cmake -DCMAKE_TOOLCHAIN_FILE=../Bela/crosscompile.cmake \
  -DUSE_DOUBLE=0 \
  -DBUILD_BELA=1 \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_INSTALL_PREFIX=/usr/ \
  -DBELA_HOME="$HOME/Bela" \
  ..

make
make install
The BELA_HOME variable points to your local Bela repository (defaults to ~/Bela).

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Toolchain file

The Bela/crosscompile.cmake configures cross-compilation: 
SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc)
SET(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++)
SET(CMAKE_FIND_ROOT_PATH /usr/arm-linux-gnueabihf)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mfloat-abi=hard -mfpu=neon")

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Create Debian package

After building with -DCMAKE_INSTALL_PREFIX=/usr/: 
cpack -G DEB \
  -D CPACK_DEBIAN_PACKAGE_ARCHITECTURE="armhf" \
  -D CPACK_PACKAGE_CONTACT="Your Name <[email protected]>" \
  -D CPACK_STRIP_FILES=true

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Using in Bela projects

Example Bela render function: 
#include <Bela.h>
#include "BelaCsound.cpp"

extern "C" Csound* csound;

bool setup(BelaContext* context, void* userData) {
    // Initialize Csound
    if (!setupCsound("test.csd", context)) {
        return false;
    }
    return true;
}

void render(BelaContext* context, void* userData) {
    // Render Csound audio
    renderCsound(context);
}

void cleanup(BelaContext* context, void* userData) {
    cleanupCsound();
}

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Daisy

Daisy is a platform for creating standalone audio devices based on the STM32H750 ARM Cortex-M7 microcontroller.

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Requirements

  • arm-none-eabi toolchain: ARM cross-compiler
  • CMake: Build system
Install toolchain:

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Build libcsound.a

From the top-level Csound source directory: 
mkdir build
cd build

cmake .. \
  -DCMAKE_INSTALL_PREFIX=../Daisy \
  -DCUSTOM_CMAKE=../Daisy/Custom.cmake \
  -DCMAKE_TOOLCHAIN_FILE=../Daisy/crosscompile.cmake

make
make install
This builds the static library libcsound.a and installs it with headers under Daisy/lib and Daisy/include.

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Custom CMake configuration

The Daisy/Custom.cmake configures a minimal Csound build: 
set(CMAKE_BUILD_TYPE "Release")
set(BARE_METAL ON)
set(BUILD_STATIC_LIBRARY ON)
set(USE_LIBSNDFILE OFF)
set(USE_ALSA OFF)
set(USE_JACK OFF)
set(USE_PORTMIDI OFF)
set(USE_PORTAUDIO OFF)
set(USE_PULSEAUDIO OFF)
set(USE_DOUBLE OFF)  # 32-bit floats for embedded
set(BUILD_MULTI_CORE OFF)
set(BUILD_UTILITIES OFF)
set(BUILD_CSOUND_COMMAND OFF)
set(REQUIRE_PTHREADS OFF)

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Toolchain file

The Daisy/crosscompile.cmake sets up ARM Cortex-M7 compilation.

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Using in Daisy projects

Add to your Daisy Makefile: 
# Csound library and headers
CSOUND_DIR = path/to/csound/Daisy

C_INCLUDES += \
    -I$(CSOUND_DIR)/include/csound

LDFLAGS += \
    -L$(CSOUND_DIR)/lib \
    -lcsound
Example Daisy code: 
#include "daisy_pod.h"
#include "csound.h"

using namespace daisy;

DaisyPod hw;
CSOUND* csound;

void AudioCallback(AudioHandle::InputBuffer in,
                   AudioHandle::OutputBuffer out,
                   size_t size) {
    // Perform one k-cycle
    csoundPerformKsmps(csound);
    
    // Get output buffer
    MYFLT* csOut = csoundGetSpout(csound);
    int nchnls = csoundGetNchnls(csound);
    
    // Copy to Daisy output
    for (size_t i = 0; i < size; i++) {
        out[0][i] = csOut[i * nchnls];
        out[1][i] = csOut[i * nchnls + 1];
    }
}

int main(void) {
    hw.Init();
    hw.SetAudioBlockSize(32);
    
    // Create Csound instance
    csound = csoundCreate(NULL);
    
    // Compile embedded CSD code
    csoundCompileOrc(csound, "sr = 48000\nksmps = 32\nnchnls = 2\n0dbfs = 1\n");
    csoundCompileOrc(csound, "instr 1\nasig oscil 0.5, 440\nouts asig, asig\nendin");
    csoundReadScore(csound, "i 1 0 -1");
    
    csoundStart(csound);
    
    hw.StartAudio(AudioCallback);
    
    while (1) {
        // Main loop
    }
}

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Example projects

The Daisy/DaisyCsoundExamples directory contains example projects:
  • DaisyCsoundProcess: Basic audio processing
  • DaisyCsoundMidi: MIDI input handling
  • DaisyCsoundGenerative: Generative synthesis
  • DaisyPodSynth: Complete synthesizer

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Other embedded platforms

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Zynq

Csound can run on Xilinx Zynq SoC devices. See Zynq/README.md for details.

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Raspberry Pi

Csound runs on Raspberry Pi using standard Linux builds: 
sudo apt-get install csound
Or build from source using Linux instructions with appropriate ARM compiler flags.

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Embedded optimization tips

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Use 32-bit floats

-DUSE_DOUBLE=0
32-bit floats reduce memory usage and improve performance on embedded processors.

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Minimize opcodes

Build only required opcodes to reduce binary size: 
set(BUILD_DEPRECATED_OPCODES OFF)
set(BUILD_OSC_OPCODES OFF)

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Optimize buffer sizes

Match hardware buffer sizes: 
<CsOptions>
-b 32    ; Match hardware buffer
-B 128   ; Output buffer
</CsOptions>

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Disable unnecessary features

set(USE_LIBSNDFILE OFF)  # No file I/O needed
set(BUILD_UTILITIES OFF)  # No command-line tools
set(BUILD_MULTI_CORE OFF) # Single-core optimization

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Real-time performance

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Priority settings

Set real-time thread priority in your application: 
#include <pthread.h>
#include <sched.h>

void setRealtimePriority() {
    struct sched_param param;
    param.sched_priority = 99;
    pthread_setschedparam(pthread_self(), SCHED_FIFO, &param);
}

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Xenomai (Bela)

Bela uses Xenomai for hard real-time performance. The build process automatically configures this.

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Memory constraints

Embedded systems have limited RAM. Monitor memory usage: 
// Check memory usage
size_t memUsed = csoundGetKsmps(csound) * 
                 csoundGetNchnls(csound) * 
                 sizeof(MYFLT);
Keep CSD files simple and avoid large tables or buffers.

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