Six Operator FM synth object for Teensy audio library.
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Holger Wirtz 8c677ceb4b Removeing direct handling from checkSystemExclusive() due to let the main code react on this check. 2 months ago
examples Several fixes for example program and 12 months ago
src Removeing direct handling from checkSystemExclusive() due to let the main code react on this check. 2 months ago
tools Fixes for 11 months ago
.gitignore Initial commit 1 year ago
LICENSE-APACHE2.txt Initial commit 1 year ago
LICENSE-GPL3.txt Initial commit 1 year ago Added methods for compressor. 3 months ago
keywords.txt Several fixes and improvements for supporting SYSEX on other platforms than Teensy. 2 months ago Cleanup. 12 months ago


Synth_Dexed is a port of the Dexed sound engine ( as library for the Teensy-3.5/3.6/4.x with an audio shield. Dexed ist heavily based on . Synth_Dexed ist SYSEX compatible with a famous 6-OP FM synth and is used in MicroDexed (


MicroDexed is licensed on the GPL v3. The msfa component (acronym for music synthesizer for android, see stays on the Apache 2.0 license to able to collaborate between projects.

Credits & thanks

  • Dexed engine by Pascal Gauthier (asb2m10)
  • DX Synth engine (as part of Dexed): Raph Levien and the msfa team
  • PPPlay : Great OPL3 implementation, with documented code :D
  • Thierry Pottier: for extreme testing, discussing about different options, images and many good suggestions for UI handling
  • Lars Pelz: Testing and documentation
  • Mark (@positionhigh) for testing


See example sketch.


AudioSynthDexed(uint8_t max_notes, uint16_t sample_rate);

// Global methods
void activate(void);
void deactivate(void);
void setMonoMode(bool mode);
bool getMonoMode(void);
void setRefreshMode(bool mode);
bool getRefreshMode(void);
void setMaxNotes(uint8_t n);
uint8_t getMaxNotes(void);
void doRefreshVoice(void);
bool decodeVoice(uint8_t* data, uint8_t* encoded_data);
bool encodeVoice(uint8_t* encoded_data);
bool getVoiceData(uint8_t* data_copy);
void setVoiceDataElement(uint8_t address, uint8_t value);
uint8_t getVoiceDataElement(uint8_t address);
void loadInitVoice(void);
void loadVoiceParameters(uint8_t* data);
uint8_t getNumNotesPlaying(void);
uint32_t getXRun(void);
uint16_t getRenderTimeMax(void);
void resetRenderTimeMax(void);
void ControllersRefresh(void);
void setCompressor(bool comp);
bool getCompressor(void);
void setCompressorPreGain_dB(float32_t pre_gain);
void setCompressorAttack_sec(float32_t attack_sec);
void setCompressorRelease_sec(float32_t release_sec);
void setCompressorThresh_dBFS(float32_t thresh_dBFS);
void setCompressionRatio(float32_t comp_ratio);
float32_t getCompressorPreGain_dB(void);
float32_t getCompressorAttack_sec(void);
float32_t getCompressorRelease_sec(void);
float32_t getCompressorThresh_dBFS(void);
float32_t getCompressionRatio(void);

// Sound methods
void keyup(int16_t pitch);
void keydown(int16_t pitch, uint8_t velo);
void setSustain(bool sustain);
bool getSustain(void);
void panic(void);
void notesOff(void);
void resetControllers(void);
void setMasterTune(int8_t mastertune);
int8_t getMasterTune(void);
void setPortamentoMode(uint8_t portamento_mode, uint8_t portamento_glissando, uint8_t portamento_time);
void setPBController(uint8_t pb_range, uint8_t pb_step);
void setMWController(uint8_t mw_range, uint8_t mw_assign, uint8_t mw_mode);
void setFCController(uint8_t fc_range, uint8_t fc_assign, uint8_t fc_mode);
void setBCController(uint8_t bc_range, uint8_t bc_assign, uint8_t bc_mode);
void setATController(uint8_t at_range, uint8_t at_assign, uint8_t at_mode);
void setModWheel(uint8_t value);
uint8_t getModWheel(void);
void setBreathController(uint8_t value);
uint8_t getBreathController(void);
void setFootController(uint8_t value);
uint8_t getFootController(void);
void setAftertouch(uint8_t value);
uint8_t getAftertouch(void);
void setPitchbend(int16_t value);
int16_t getPitchbend(void);
void setPitchbendRange(uint8_t range);
uint8_t getPitchbendRange(void);
void setPitchbendStep(uint8_t step);
uint8_t getPitchbendStep(void);
void setModWheelRange(uint8_t range);
uint8_t getModWheelRange(void);
void setModWheelTarget(uint8_t target);
uint8_t getModWheelTarget(void);
void setFootControllerRange(uint8_t range);
uint8_t getFootControllerRange(void);
void setFootControllerTarget(uint8_t target);
uint8_t getFootControllerTarget(void);
void setBreathControllerRange(uint8_t range);
uint8_t getBreathControllerRange(void);
void setBreathControllerTarget(uint8_t target);
uint8_t getBreathControllerTarget(void);
void setAftertouchRange(uint8_t range);
uint8_t getAftertouchRange(void);
void setAftertouchTarget(uint8_t target);
uint8_t getAftertouchTarget(void);
void setFilterCutoff(float cutoff);
float getFilterCutoff(void);
void setFilterResonance(float resonance);
float getFilterResonance(void);
void setGain(float gain);
float getGain(void);

// Voice configuration methods
void setOPAll(uint8_t ops);
void setOP(uint8_t op, bool state);
bool getOP(uint8_t op);
void setOPRateAll(uint8_t rate);
void setOPLevelAll(uint8_t level);
void setOPRateAllCarrier(uint8_t step, uint8_t rate);
void setOPLevelAllCarrier(uint8_t step, uint8_t level);
void setOPRateAllModulator(uint8_t step, uint8_t rate);
void setOPLevelAllModulator(uint8_t step, uint8_t level);
void setOPRate(uint8_t op, uint8_t step, uint8_t rate);
uint8_t getOPRate(uint8_t op, uint8_t step);
void setOPLevel(uint8_t op, uint8_t step, uint8_t level);
uint8_t getOPLevel(uint8_t op, uint8_t step);
void setOPKeyboardLevelScalingBreakPoint(uint8_t op, uint8_t level);
uint8_t getOPKeyboardLevelScalingBreakPoint(uint8_t op);
void setOPKeyboardLevelScalingDepthLeft(uint8_t op, uint8_t depth);
uint8_t getOPKeyboardLevelScalingDepthLeft(uint8_t op);
void setOPKeyboardLevelScalingDepthRight(uint8_t op, uint8_t depth);
uint8_t getOPKeyboardLevelScalingDepthRight(uint8_t op);
void setOPKeyboardLevelScalingCurveLeft(uint8_t op, uint8_t curve);
uint8_t getOPKeyboardLevelScalingCurveLeft(uint8_t op);
void setOPKeyboardLevelScalingCurveRight(uint8_t op, uint8_t curve);
uint8_t getOPKeyboardLevelScalingCurveRight(uint8_t op);
void setOPKeyboardRateScale(uint8_t op, uint8_t scale);
uint8_t getOPKeyboardRateScale(uint8_t op);
void setOPAmpModulationSensity(uint8_t op, uint8_t sensitivity);
uint8_t getOPAmpModulationSensity(uint8_t op);
void setOPKeyboardVelocitySensity(uint8_t op, uint8_t sensitivity);
uint8_t getOPKeyboardVelocitySensity(uint8_t op);
void setOPOutputLevel(uint8_t op, uint8_t level);
uint8_t getOPOutputLevel(uint8_t op);
void setOPMode(uint8_t op, uint8_t mode);
uint8_t getOPMode(uint8_t op);
void setOPFrequencyCoarse(uint8_t op, uint8_t frq_coarse);
uint8_t getOPFrequencyCoarse(uint8_t op);
void setOPFrequencyFine(uint8_t op, uint8_t frq_fine);
uint8_t getOPFrequencyFine(uint8_t op);
void setOPDetune(uint8_t op, uint8_t detune);
uint8_t getOPDetune(uint8_t op);
void setPitchRate(uint8_t step, uint8_t rate);
uint8_t getPitchRate(uint8_t step);
void setPitchLevel(uint8_t step, uint8_t level);
uint8_t getPitchLevel(uint8_t step);
void setAlgorithm(uint8_t algorithm);
uint8_t getAlgorithm(void);
void setFeedback(uint8_t feedback);
uint8_t getFeedback(void);
void setOscillatorSync(bool sync);
bool getOscillatorSync(void);
void setLFOSpeed(uint8_t speed);
uint8_t getLFOSpeed(void);
void setLFODelay(uint8_t delay);
uint8_t getLFODelay(void);
void setLFOPitchModulationDepth(uint8_t depth);
uint8_t getLFOPitchModulationDepth(void);
void setLFOAmpModulationDepth(uint8_t delay);
uint8_t getLFOAmpModulationDepth(void);
void setLFOSync(bool sync);
bool getLFOSync(void);
void setLFOWaveform(uint8_t waveform);
uint8_t getLFOWaveform(void);
void setLFOPitchModulationSensitivity(uint8_t sensitivity);
uint8_t getLFOPitchModulationSensitivity(void);
void setTranspose(uint8_t transpose);
uint8_t getTranspose(void);
void setName(char* name);
void getName(char* buffer);