Digital Synth PRA32-U v3.3.2

4-Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v3.3.2 (2026-03-14):
  • Fix "pra32-u-make-sample-wav-file.cc"
  • Tested with Arduino-Pico version 5.5.1
• v3.3.1 (2026-03-13):
  • Improve customizability
  • Tested with Arduino-Pico version 5.5.1
• v3.3.0 (2026-03-12):
  • Fix a problem with EG/Amp Sustain level not changing in note on states
  • Fix a problem with the meaning of the Filter Resonance control value (Parameter Guide also modified)
  • PRA32-U Editor: Improve stability when using Hairless MIDI<->Serial Bridge on Windows
  • Fix documentation
  • Discontinue the binary release of "Digital-Synth-PRA32-U-PWM-Audio.uf2"
  • Other improvements
  • Tested with Arduino-Pico version 5.5.1

Known Issues

• When using PWM Audio, signal discontinuity occurs approximately every 60-80 milliseconds
  • Click noise is particularly noticeable in the high frequency band and sine waves

Notes

• Waveshare Pico-Audio Rev2.1 Version is CURRENTLY NOT RECOMMENDED
  • No sound unless using Arduino-Pico 4.4.0

Special Thanks

• PRA32-U Editor for Renoise by plantssystem

Digital Synth PRA32-U v3.3.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v3.3.1 (2026-03-13):
  • Improve customizability
  • Tested with Arduino-Pico version 5.5.1
• v3.3.0 (2026-03-12):
  • Fix a problem with EG/Amp Sustain level not changing in note on states
  • Fix a problem with the meaning of the Filter Resonance control value (Parameter Guide also modified)
  • PRA32-U Editor: Improve stability when using Hairless MIDI<->Serial Bridge on Windows
  • Fix documentation
  • Discontinue the binary release of "Digital-Synth-PRA32-U-PWM-Audio.uf2"
  • Other improvements
  • Tested with Arduino-Pico version 5.5.1

Known Issues

• When using PWM Audio, signal discontinuity occurs approximately every 60-80 milliseconds
  • Click noise is particularly noticeable in the high frequency band and sine waves

Digital Synth PRA32-U v3.3.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v3.3.0 (2026-03-12):
  • Fix a problem with EG/Amp Sustain level not changing in note on states
  • Fix a problem with the meaning of the Filter Resonance control value (Parameter Guide also modified)
  • PRA32-U Editor: Improve stability when using Hairless MIDI<->Serial Bridge on Windows
  • Fix documentation
  • Discontinue the binary release of "Digital-Synth-PRA32-U-PWM-Audio.uf2"
  • Other improvements
  • Tested with Arduino-Pico version 5.5.1

Known Issues

• When using PWM Audio, signal discontinuity occurs approximately every 60-80 milliseconds
  • Click noise is particularly noticeable in the high frequency band and sine waves

Digital Synth PRA32-U v3.2.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Known Issues

• When using PWM Audio, signal discontinuity occurs approximately every 60-80 milliseconds
  • Click noise is particularly noticeable in the high frequency band and sine waves

Change History

• v3.2.0 (2025-05-11):
  • Renew High Pass Filter: No noise when changing Resonance
  • Fix a problem with Voice Assign Mode not being set to Mode 2 when the value is 1
  • PRA32-U with Panel: Fix a problem with Sustain Pedal being displayed as On when the value is 1
  • Fix documentation
  • Other improvements
  • Tested with Arduino-Pico version 4.5.3

Digital Synth PRA32-U v3.1.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v3.1.0 (2025-01-19):
  • Add the Voice Assign Mode [1|2] parameter
    • Old versions is equivalent to Mode 2
  • Sine Wave (Phase Modulation): Change the unit of Frequency Ratio from 0.25 to 0.5
  • Sine Wave (Phase Modulation): Improve Frequency Ratio to change smoothly
  • Extend Osc 2 Pitch range (-5 to +7 -> -12 to +12 semitone)
  • Extend Pitch modulation range by EG Osc Amt and LFO Osc Amt (-24 to +24 -> -30 to +30 semitone)
  • PRA32-U with Panel: Change MIDI clock and commands not to be transmitted via USB MIDI
    • To avoid freeze problem when transmitting and receiving USB MIDI at the same time
  • PRA32-U with Panel: Add the Filter EG Amt parameter to the EG pages as well
  • PRA32-U with Panel: Rename the parameter name Seq Pattern to Seq Mode
  • PRA32-U with Panel: Reduce memory usage
    • Fix an issue where emulated EEPROM would not work with some compilation options
  • Other improvements
  • Tested with Arduino-Pico version 4.4.1
    • Overclock to 153.6 MHz (instead of 147.6 MHz)
• v3.0.0 (2024-11-13):
  • Change Control Numbers: Osc 1 Wave 102 to 14, Voice Mode 14 to 102
  • Mixer Noise is not disabled even if Osc 2 Wave is Nos (Noise)
  • Change Preset programs: Change Delay Mode to S (Stereo Delay)
  • Rename PRA32-U CTRL to PRA32-U Editor
  • Officially support the option PRA32-U with Panel
    • Faster OLED display updates
    • Change the page layout and the default pages
    • Change the specification of Panel Scale parameter
    • Change the specification of Seq Last Step parameter and rename Seq Last Step to Seq Num Steps (Number of Steps)
    • Add Panel Pitch Ofst (Pitch Offset) parameter
    • Add Seq On Steps parameter
    • Add Seq Rand Pitch (Randomize Pitch 0-7) function
    • Add Seq Rand Velo (Randomize Velo 0-7) function
    • Fix Seq Gate Time behavior
  • Tested with Arduino-Pico version 4.2.0

Digital Synth PRA32-U v3.0.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v3.0.0 (2024-11-13):
  • Change Control Numbers: Osc 1 Wave 102 to 14, Voice Mode 14 to 102
  • Mixer Noise is not disabled even if Osc 2 Wave is Nos (Noise)
  • Change Preset programs: Change Delay Mode to S (Stereo Delay)
  • Rename PRA32-U CTRL to PRA32-U Editor
  • Officially support the option PRA32-U with Panel
    • Faster OLED display updates
    • Change the page layout and the default pages
    • Change the specification of Panel Scale parameter
    • Change the specification of Seq Last Step parameter and rename Seq Last Step to Seq Num Steps (Number of Steps)
    • Add Panel Pitch Ofst (Pitch Offset) parameter
    • Add Seq On Steps parameter
    • Add Seq Rand Pitch (Randomize Pitch 0-7) function
    • Add Seq Rand Velo (Randomize Velo 0-7) function
    • Fix Seq Gate Time behavior
  • Tested with Arduino-Pico version 4.2.0

Digital Synth PRA32-U v2.6.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.6.1 (2024-09-22):
  • Fix Bug: PWM Audio: Notes are played a whole tone higher
  • Other improvements
• v2.6.0 (2024-09-15):
  • Extend "Delay Time" range (20-300 to 1-333.3 ms)
  • Update the option PRA32-U with Panel to Prototype 3 (experimental)
    • Add the parameter "Seq Step Note" (Quarter Note, Eighth Note, Sixteenth Note)
    • "Panel Play Pitch" and "Seq Pitch 0-7" displays reflect "Panel Transpose" (but not "Seq Transpose")
    • Fix "Panel Scale", "Panel Transpose", and "Seq Transpose" update timing in "Seq Pattern" Reverse and Bounce
    • Fix a problem with "Seq Pattern" displaying incorrectly when the value is 1
  • PRA32-U CTRL, PRA32-U with Panel: Add ms display of "Delay Time"
  • Fix MIDI Implementation Chart
  • Other improvements
  • Tested with Arduino-Pico version 4.0.2

Digital Synth PRA32-U v2.6.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Bugs

• PWM Audio: Notes are played a whole tone higher

Change History

• v2.6.0 (2024-09-15):
  • Extend "Delay Time" range (20-300 to 1-333.3 ms)
  • Update the option PRA32-U with Panel to Prototype 3 (experimental)
    • Add the parameter "Seq Step Note" (Quarter Note, Eighth Note, Sixteenth Note)
    • "Panel Play Pitch" and "Seq Pitch 0-7" displays reflect "Panel Transpose" (but not "Seq Transpose")
    • Fix "Panel Scale", "Panel Transpose", and "Seq Transpose" update timing in "Seq Pattern" Reverse and Bounce
    • Fix a problem with "Seq Pattern" displaying incorrectly when the value is 1
  • PRA32-U CTRL, PRA32-U with Panel: Add ms display of "Delay Time"
  • Fix MIDI Implementation Chart
  • Other improvements
  • Tested with Arduino-Pico version 4.0.2

Digital Synth PRA32-U v2.5.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.5.1 (2024-09-08):
  • Fix a problem with noise in PRA32-U CTRL Recall operation when PWM Audio is used
    • This problem occurred when 3 or 4 notes were playing in Poly Mode and PRA32_U_USE_DEBUG_PRINT was commented out (default)
  • Add description to Delay Time in Parameter Guide
• v2.5.0 (2024-09-04):
  • PRA32-U with Panel: Support MIDI Clock and Start/Stop Commands transmission
  • Fix "pra32-u-make-sample-wav-file.cc"
  • Other changes
  • Tested with Arduino-Pico version 4.0.1

Digital Synth PRA32-U v2.5.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.5.0 (2024-09-04):
  • PRA32-U with Panel: Support MIDI Clock and Start/Stop Commands transmission
  • Fix "pra32-u-make-sample-wav-file.cc"
  • Other changes
  • Tested with Arduino-Pico version 4.0.1

Digital Synth PRA32-U v2.4.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.4.1 (2024-09-01):
  • PRA32-U with Panel: Fix a problem with MIDI clock being processed even when sequencer is stopped
  • PRA32-U with Panel: Fix a problem where Start/Stop MIDI commands are processed even when Seq Clock Src is Internal
  • Fix MIDI Implementation Chart
  • Tested with Arduino-Pico version 4.0.1
• v2.4.0 (2024-08-25):
  • Increase the output level using Extra Amp and Limiter
  • For safety, change the mode of the PWM audio output pins to OUTPUT_12MA
  • Update the option PRA32-U with Panel to Prototype 2 (experimental)
    • Change the page structure (Add the page groups A, B, C, and D)
    • Change the specification of "Panel Scale"
    • Add the parameter "Panel MIDI Ch" (Basic Channel)
    • Add Step Sequencer Mode ("Seq") to "Panel Play Mode"
    • Add the option PRA32_U_KEY_INPUT_PIN_MODE (default: INPUT_PULLDOWN)
    • Add the functions "Write Panel Prms", "Read Panel Prms", and "Init Panel Prms"
  • PRA32-U CTRL: Change the Note ON velocity to 64
  • Other changes
  • Tested with Arduino-Pico version 3.9.5

Digital Synth PRA32-U v2.4.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.4.0 (2024-08-25):
  • Increase the output level using Extra Amp and Limiter
  • For safety, change the mode of the PWM audio output pins to OUTPUT_12MA
  • Update the option PRA32-U with Panel to Prototype 2 (experimental)
    • Change the page structure (Add the page groups A, B, C, and D)
    • Change the specification of "Panel Scale"
    • Add the parameter "Panel MIDI Ch" (Basic Channel)
    • Add Step Sequencer Mode ("Seq") to "Panel Play Mode"
    • Add the option PRA32_U_KEY_INPUT_PIN_MODE (default: INPUT_PULLDOWN)
    • Add the functions "Write Panel Prms", "Read Panel Prms", and "Init Panel Prms"
  • PRA32-U CTRL: Change the Note ON velocity to 64
  • Other changes
  • Tested with Arduino-Pico version 3.9.5

Digital Synth PRA32-U v2.3.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.3.1 (2024-04-21):
  • Abolish the option to write user programs to the flash when using PWM audio due to performance problem uncovered
  • Tested with Arduino-Pico version 3.7.2
• v2.3.0 (2024-04-21):
  • Allow user programs to be written to the flash when using I2S DAC without mute-off pin
  • Add the option to write user programs to the flash when using PWM audio (for Raspberry Pi Pico/H/W/WH)
  • Add the option PRA32_U_I2S_SWAP_LEFT_AND_RIGHT
  • Add the option PRA32-U with Panel, Prototype 1 (experimental)
  • Change the default program #0 to #8
  • Use core 1 for Debug Print
  • Other changes
  • Tested with Arduino-Pico version 3.7.2

Digital Synth PRA32-U v2.2.2

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.2.2 (2024-02-10):
  • Fix a bug that the parameters are not written to the flash when using I2S DAC, even if PRA32_U_I2S_DAC_MUTE_OFF_PIN is defined
  • Tested with Arduino-Pico version 3.7.0
• v2.2.1 (2024-02-04):
  • No more need to install Adafruit TinyUSB Library separately from Arduino-Pico
• v2.2.0 (2024-01-26):
  • Use error diffusion for PWM audio output by default
  • Eliminate noise when PWM audio output is silent
  • Change the display of PRA32-U CTRL
  • Modify Presets;
  • Tested with Adafruit TinyUSB Library version 2.3.3
• v2.1.0 (2024-01-14):
  • Reduce noise from PMIC (Turn off RT6150 Power Save);
  • Support Osc 1 Sine Wave Phase Modulation (Osc 1 Shape and Osc 1 Morph);
  • Add the function of writing the parameters to Program #8-15 and the flash;
  • Modify Presets;
  • Add JSON files for PRA32-U CTRL;
  • Use core 0 for main processing;
  • Rename constant macros;
  • Officially support PWM audio output option;
  • Rename Serial MIDI to UART MIDI;
  • Enable UART MIDI to be used at the same time as USB MIDI;
  • Use Serial1 for Debug Print and Serial2 for UART MIDI;
  • Raspberry Pi Pico/RP2040 core version 3.6.3 is recommended
• v2.0.1 (2024-01-05):
  • Fix Ping Pong Delay to start from the left
  • Fix Parameter Guide (Filter Resonance)
• v2.0.0 (2024-01-04):
  • Add Delay Mode (Ping Pong Delay);
  • Support Breath Controller (Breath Filter Amt and Breath Amp Mod);
  • Support Note ON Velocity (EG Velocity Sensitivity and Amp Velocity Sensitivity);
  • Modify EG and Amp EG;
  • Modify Presets;
  • Change the control numbers of Control Changes (Voice Mode: 27 -> 14, LFO Wave: 18 -> 12, Filter Mode: 86 -> 78, EG Amp Mod: 87 -> 28, and Chorus Mix: 93 -> 27);
  • Change the meanings of the values of Control Changes (Osc 1 Wave, Osc 2 Wave, EG Osc Dst, Voice Mode, LFO Wave, LFO Osc Dst, Filter Mode, EG Amp Mod, Release = Decay, Breath Amp Mod, and Delay Mode);
  • Increase DMA buffer size (audio latency: 2.7 ms -> 5.3 ms);
  • Use 2 cores for signal processing in Polyphonic and Paraphonic Modes;
  • Add PWM audio output option (experimental)

Digital Synth PRA32-U v2.2.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.2.1 (2024-02-04):
  • No more need to install Adafruit TinyUSB Library separately from Arduino-Pico
• v2.2.0 (2024-01-26):
  • Use error diffusion for PWM audio output by default
  • Eliminate noise when PWM audio output is silent
  • Change the display of PRA32-U CTRL
  • Modify Presets;
  • Tested with Adafruit TinyUSB Library version 2.3.3
• v2.1.0 (2024-01-14):
  • Reduce noise from PMIC (Turn off RT6150 Power Save);
  • Support Osc 1 Sine Wave Phase Modulation (Osc 1 Shape and Osc 1 Morph);
  • Add the function of writing the parameters to Program #8-15 and the flash;
  • Modify Presets;
  • Add JSON files for PRA32-U CTRL;
  • Use core 0 for main processing;
  • Rename constant macros;
  • Officially support PWM audio output option;
  • Rename Serial MIDI to UART MIDI;
  • Enable UART MIDI to be used at the same time as USB MIDI;
  • Use Serial1 for Debug Print and Serial2 for UART MIDI;
  • Raspberry Pi Pico/RP2040 core version 3.6.3 is recommended
• v2.0.1 (2024-01-05):
  • Fix Ping Pong Delay to start from the left
  • Fix Parameter Guide (Filter Resonance)
• v2.0.0 (2024-01-04):
  • Add Delay Mode (Ping Pong Delay);
  • Support Breath Controller (Breath Filter Amt and Breath Amp Mod);
  • Support Note ON Velocity (EG Velocity Sensitivity and Amp Velocity Sensitivity);
  • Modify EG and Amp EG;
  • Modify Presets;
  • Change the control numbers of Control Changes (Voice Mode: 27 -> 14, LFO Wave: 18 -> 12, Filter Mode: 86 -> 78, EG Amp Mod: 87 -> 28, and Chorus Mix: 93 -> 27);
  • Change the meanings of the values of Control Changes (Osc 1 Wave, Osc 2 Wave, EG Osc Dst, Voice Mode, LFO Wave, LFO Osc Dst, Filter Mode, EG Amp Mod, Release = Decay, Breath Amp Mod, and Delay Mode);
  • Increase DMA buffer size (audio latency: 2.7 ms -> 5.3 ms);
  • Use 2 cores for signal processing in Polyphonic and Paraphonic Modes;
  • Add PWM audio output option (experimental)

Digital Synth PRA32-U v2.2.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.2.0 (2024-01-26):
  • Use error diffusion for PWM audio output by default
  • Eliminate noise when PWM audio output is silent
  • Change the display of PRA32-U CTRL
  • Modify Presets;
  • Tested with Adafruit TinyUSB Library version 2.3.3
• v2.1.0 (2024-01-14):
  • Reduce noise from PMIC (Turn off RT6150 Power Save);
  • Support Osc 1 Sine Wave Phase Modulation (Osc 1 Shape and Osc 1 Morph);
  • Add the function of writing the parameters to Program #8-15 and the flash;
  • Modify Presets;
  • Add JSON files for PRA32-U CTRL;
  • Use core 0 for main processing;
  • Rename constant macros;
  • Officially support PWM audio output option;
  • Rename Serial MIDI to UART MIDI;
  • Enable UART MIDI to be used at the same time as USB MIDI;
  • Use Serial1 for Debug Print and Serial2 for UART MIDI;
  • Raspberry Pi Pico/RP2040 core version 3.6.3 is recommended
• v2.0.1 (2024-01-05):
  • Fix Ping Pong Delay to start from the left
  • Fix Parameter Guide (Filter Resonance)
• v2.0.0 (2024-01-04):
  • Add Delay Mode (Ping Pong Delay);
  • Support Breath Controller (Breath Filter Amt and Breath Amp Mod);
  • Support Note ON Velocity (EG Velocity Sensitivity and Amp Velocity Sensitivity);
  • Modify EG and Amp EG;
  • Modify Presets;
  • Change the control numbers of Control Changes (Voice Mode: 27 -> 14, LFO Wave: 18 -> 12, Filter Mode: 86 -> 78, EG Amp Mod: 87 -> 28, and Chorus Mix: 93 -> 27);
  • Change the meanings of the values of Control Changes (Osc 1 Wave, Osc 2 Wave, EG Osc Dst, Voice Mode, LFO Wave, LFO Osc Dst, Filter Mode, EG Amp Mod, Release = Decay, Breath Amp Mod, and Delay Mode);
  • Increase DMA buffer size (audio latency: 2.7 ms -> 5.3 ms);
  • Use 2 cores for signal processing in Polyphonic and Paraphonic Modes;
  • Add PWM audio output option (experimental)

Digital Synth PRA32-U v2.1.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.1.0 (2024-01-14):
  • Reduce noise from PMIC (Turn off RT6150 Power Save);
  • Support Osc 1 Sine Wave Phase Modulation (Osc 1 Shape and Osc 1 Morph);
  • Add the function of writing the parameters to Program #8-15 and the flash;
  • Modify Presets;
  • Add JSON files for PRA32-U CTRL;
  • Use core 0 for main processing;
  • Rename constant macros;
  • Officially support PWM audio output option;
  • Rename Serial MIDI to UART MIDI;
  • Enable UART MIDI to be used at the same time as USB MIDI;
  • Use Serial1 for Debug Print and Serial2 for UART MIDI;
  • Raspberry Pi Pico/RP2040 core version 3.6.3 is recommended
• v2.0.1 (2024-01-05):
  • Fix Ping Pong Delay to start from the left
  • Fix Parameter Guide (Filter Resonance)
• v2.0.0 (2024-01-04):
  • Add Delay Mode (Ping Pong Delay);
  • Support Breath Controller (Breath Filter Amt and Breath Amp Mod);
  • Support Note ON Velocity (EG Velocity Sensitivity and Amp Velocity Sensitivity);
  • Modify EG and Amp EG;
  • Modify Presets;
  • Change the control numbers of Control Changes (Voice Mode: 27 -> 14, LFO Wave: 18 -> 12, Filter Mode: 86 -> 78, EG Amp Mod: 87 -> 28, and Chorus Mix: 93 -> 27);
  • Change the meanings of the values of Control Changes (Osc 1 Wave, Osc 2 Wave, EG Osc Dst, Voice Mode, LFO Wave, LFO Osc Dst, Filter Mode, EG Amp Mod, Release = Decay, Breath Amp Mod, and Delay Mode);
  • Increase DMA buffer size (audio latency: 2.7 ms -> 5.3 ms);
  • Use 2 cores for signal processing in Polyphonic and Paraphonic Modes;
  • Add PWM audio output option (experimental)

Digital Synth PRA32-U v2.0.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.0.1:
  • Fix Ping Pong Delay to start from the left
  • Fix Parameter Guide (Filter Resonance)
• v2.0.0:
  • Add Delay Mode (Ping Pong Delay);
  • Support Breath Controller (Breath Filter Amt and Breath Amp Mod);
  • Support Note ON Velocity (EG Velocity Sensitivity and Amp Velocity Sensitivity);
  • Modify EG and Amp EG;
  • Modify Presets;
  • Change the control numbers of Control Changes (Voice Mode: 27 -> 14, LFO Wave: 18 -> 12, Filter Mode: 86 -> 78, EG Amp Mod: 87 -> 28, and Chorus Mix: 93 -> 27);
  • Change the meanings of the values of Control Changes (Osc 1 Wave, Osc 2 Wave, EG Osc Dst, Voice Mode, LFO Wave, LFO Osc Dst, Filter Mode, EG Amp Mod, Release = Decay, Breath Amp Mod, and Delay Mode);
  • Increase DMA buffer size (audio latency: 2.7 ms -> 5.3 ms);
  • Use 2 cores for signal processing in Polyphonic and Paraphonic Modes;
  • Add PWM audio output option (experimental)

Digital Synth PRA32-U v2.0.0

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v2.0.0:
  • Add Delay Mode (Ping Pong Delay);
  • Support Breath Controller (Breath Filter Amt and Breath Amp Mod);
  • Support Note ON Velocity (EG Velocity Sensitivity and Amp Velocity Sensitivity);
  • Modify EG and Amp EG;
  • Modify Presets;
  • Change the control numbers of Control Changes (Voice Mode: 27 -> 14, LFO Wave: 18 -> 12, Filter Mode: 86 -> 78, EG Amp Mod: 87 -> 28, and Chorus Mix: 93 -> 27);
  • Change the meanings of the values of Control Changes (Osc 1 Wave, Osc 2 Wave, EG Osc Dst, Voice Mode, LFO Wave, LFO Osc Dst, Filter Mode, EG Amp Mod, Release = Decay, Breath Amp Mod, and Delay Mode);
  • Increase DMA buffer size (audio latency: 2.7 ms -> 5.3 ms);
  • Use 2 cores for signal processing in Polyphonic and Paraphonic Modes;
  • Add PWM audio output option (experimental)

Digital Synth PRA32-U v1.2.1

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico/RP2040

Change History

• v1.2.1: Fixed an oscillation problem caused by Delay Feedback
• v1.2.0: Renew High Pass Filter; Raspberry Pi Pico/RP2040 core version 3.6.2 is recommended
• v1.1.1: Revert Filter clipping in High Pass mode
• v1.1.0: Fix Filter clipping (behavior during oscillation); Extend Pitch Bend Range; Delete the code for Waveshare Pico-Audio Rev2.1
• v1.0.3: Fix a problem with received MIDI messages being dropped; Improve README; Fix UF2 files
• v1.0.2: Turn MIDI Thru Off
• v1.0.1: Fix unstable PRA32-U CTRL operation when using Serial MIDI (DIN/TRS MIDI); Fix README