picoFn

2 channel MIDI controlled audio function generator.

Features

• Full MIDI control - via MIDI over USB or physical MIDI
• Two channels
• Sine, triangle, ramp-up, ramp-down, square, pulse, noise waveforms
• Sample rate 96 KHz
• Frequency range 0.1Hz to 20KHz
• Coarse tune with semitone resolution G-1# to D10
• Fine tune with semitone range
• Phase shift / pulse width
• Attenuation 0dB to 60dB and infinity
• Modulation/mix of right channel by/with left - Amplitude (AM), Ring (RM), Frequency (FM), Pulse Width (PWM), Mix

To Do

• Try some higher sample rates

MIDI controls

MIDI chan	MIDI type	MIDI value	Output	Description
1	CTL	2, 16	Left	Coarse freqeuncy (semitone)
1	CTL	3, 17	Left	Fine freqeuncy (semitone/128)
1	CTL	4, 18	Left	Phase shift / pulse width
1	CTL	5, 19	Left	Attenuation (dB)
1	PGM	4	Left	Waveform select down
1	PGM	5	Left	Waveform select up
1	NON	1	Left	Waveform select down
1	NON	3	Left	Waveform select up
1	NON	10	Left	Toggle LFO mode	0.101 Hz - 151.5 Hz
1	CTL	6, 20	Right	Coarse freqeuncy (semitone)
1	CTL	7, 21	Right	Fine freqeuncy (semitone/128)
1	CTL	8, 22	Right	Phase shift / pulse width
1	CTL	9, 24	Right	Attenuation (dB)
1	PGM	0	Right	Waveform select down
1	PGM	1	Right	Waveform select up
1	NON	4	Right	Waveform select down
1	NON	6	Right	Waveform select up
1	NON	7	Right	Modulation select up
1	NON	9	Right	Modulation select down
1	NON	note	Left/Right	Coarse frequency for MIDI note value

NOTE: These controls have been selected to work with the AKAI MPKmini or AKAI MIDImix controllers.

Hardware

Re-uses the picoX7 hardware platform. See README

                   +-----------+
(Debug) TX UART <- |  1     40 | <> vbus +5v
                   |  2     39 | <> vsys
            gnd ## |  3     38 | ## gnd
                   |  4     37 | <- 3v3-en
                   |  5     36 | -> 3v3
                   |  6     35 | <- adc-vref
                   |  7     34 | -> I2S LRCLK
            gnd ## |  8     33 | ## agnd
                   |  9     32 | -> I2S SCLK
                   | 10     31 | -> I2S SD
                   | 11     30 | <- run
                   | 12     29 |    
            gnd ## | 13     28 | ## gnd
                   | 14     27 | <- UART RX (MIDI in)
                   | 15     26 |    
                   | 16     25 | -> I2C SCL (16x2 LCD)
                   | 17     24 | -> I2C SDA (16x2 LCD)
            gnd ## | 18     23 | ## gnd
                   | 19     22 |    
                   | 20     21 |    
                   +-----------+

Software

Dependencies

• https://github.com/SloeComputers/Hardware
• https://github.com/SloeComputers/Platform
• arm-none-eabi-gcc
• cmake
• ninja (make works too)

Checkout

This repo uses git sub-modules, so checkout using –recurse-submodules to clone all the dependent source…

git clone --recurse-submodules https://github.com/SloeComputers/picoFn.git

or

git clone --recurse-submodules ssh://git@github.com/SloeComputers/picoFn.git

Build

Being developed on MacOS but should build on Linux too.

make

Build directly using cmake…

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DPLT_TARGET=rp2350 -DCMAKE_TOOLCHAIN_FILE=Platform/MTL/rp2350/target/toolchain.cmake ..
make

Flashable image will be found under the build sub directory here…

.../Source/picoFn_RPIPICO_I2S_DAC.uf2

License

This project is licensed under the MIT License - see the LICENSE file for details