# MiniDexed 
MiniDexed is a FM synthesizer closely modeled on the famous DX7 by a well-known Japanese manufacturer running on a bare metal Raspberry Pi (without a Linux kernel or operating system). On Pi Raspberry 2 and larger, it can run 8 tone generators, basically creating an open source equivalent of the TX816/TX802 (8 DX7 instances without the keyboard in one box).
## Features
- [x] Get [Synth_Dexed ](https://codeberg.org/dcoredump/Synth_Dexed ) to build with [circle-stdlib ](https://github.com/smuehlst/circle-stdlib )
- [x] Upload SD card contents to [GitHub Releases ](../../releases )
- [x] Get it to build for and boot on a Raspberry Pi 4
- [x] Get it to react to USB MIDI
- [x] Get it to react to MIDI via Raspberry Pi 4 GPIO
- [x] Get it to produce some sound on the headphone jack
- [x] Get it to produce some sound produced by Dexed
- [x] Load a default (hardcoded) sysex
- [x] Get it to build for and boot on a Raspberry Pi 3
- [x] Get it to build for and boot on a Raspberry Pi 2
- [x] Get it to build for and boot on a Raspberry Pi 1 and Raspberry Pi Zero
- [x] Support multiple voices through Program Change and Bank Change LSB/MSB MIDI messages
- [x] Add functionality for loading `.syx` files from SD card (e.g., using `getsysex.sh` or from [Dexed_cart_1.0.zip ](http://hsjp.eu/downloads/Dexed/Dexed_cart_1.0.zip ))
- [x] Show voice name on optional [HD44780 display ](https://www.berrybase.de/sensoren-module/displays/alphanumerische-displays/alphanumerisches-lcd-16x2-gr-252-n/gelb )
- [x] Support selecting patches using MIDI Bank Change and Program Change messages
- [x] Get 8 Dexed instances to run simultaneously (like in a TX816) and mix their output together
- [x] Allow for each Dexed instance to be detuned and stereo shifted
- [x] Add a way to configure multiple Dexed instances through `performance.ini` files
- [ ] Add a way to configure multiple Dexed instances through Performance `.syx` files
- [ ] Add a way to configure multiple Dexed instances through Performance sysex messages
- [x] Add compressor effect
- [x] Add reverb effect
- [ ] Make it possible to assign voice parameters to sliders and knobs on MIDI controllers
Contributions are highly welcome.
## Usage
* In the case of Raspberry Pi 4, Update the firmware and bootloader to the latest version (not doing this may cause USB reliability issues)
* Download from [GitHub Releases ](../../releases )
* Unzip
* Put the files into the root directory of a FAT32 formatted partition on SD/microSD card
* Put SD/microSD card into Raspberry Pi 1, 2, 3 or 4 (Zero and Zero 2 can probably be used but need HDMI or a supported i2c DAC for audio out)
* Attach headphones to the headphone jack using `SoundDevice=pwm` in `minidexed.ini` (default) (poor audio quality)
* Alternatively, attach a PCM5102A or PCM5122 based DAC and select i2c sound output using `SoundDevice=i2s` in `minidexed.ini` (best audio quality)
* Alternatively, attach a HDMI display with sound and select HDMI sound output using `SoundDevice=hdmi` in `minidexed.ini` (this may introduce slight latency)
* Attach a MIDI keyboard via USB
* Boot
* Start playing
* See the Wiki for [Menu ](https://github.com/probonopd/MiniDexed/wiki/Menu ) operation
## Pinout
All devices on Raspberry Pi GPIOs are **optional** .
__CAUTION:__ All GPIO numbers are [chip numbers ](https://pinout.xyz/ ), not header positions.
|GPIO | Device | | Function | Direction | Comment|
|---|---|---|---|---|---|
|14 | UART | | TXD | | OUT | | serial MIDI|
|15 | UART | | RXD | | IN | | serial MIDI|
|18 | DAC | | CLK | | OUT|
|19 | DAC | | FS | | OUT|
|21 | DAC | | DOUT | | OUT|
|02 | I2C | | SDA | | IN/OUT | | used by some DACs|
|03 | I2C | | SCL | | OUT | | used by some DACs|
|17 | LCD | | EN | | OUT | | default setting|
|27 | LCD | | RS | | OUT | | default setting|
|16 | LCD | | RW | | OUT | | default setting, optional|
|22 | LCD | | D4 | | OUT | | default setting|
|23 | LCD | | D5 | | OUT | | default setting|
|24 | LCD | | D6 | | OUT | | default setting|
|25 | LCD | | D7 | | OUT | | default setting|
|05 | ROTARY ENCODER | CLK (ENC A) | IN | | default setting|
|06 | ROTARY ENCODER | DT (ENC B) | IN | | default setting|
|26 | ROTARY ENCODER | SW | | IN | | default setting|
|12 | PWM AUDIO | PWM0 | | OUT | | on Raspberry Pi Zero|
|13 | PWM AUDIO | PWM1 | | OUT | | on Raspberry Pi Zero|
|07 | SPI | | /CE1 | | OUT | | reserved|
|08 | SPI | | /CE0 | | OUT | | reserved|
|09 | SPI | | MISO | | IN | | reserved|
|10 | SPI | | MOSI | | OUT | | reserved|
|11 | SPI | | SCLK | | OUT | | reserved|
|04 | NONE | | | | | | can generate clock signal|
|20 | NONE | | | | | | may be used for DAC DIN|
## Building locally
E.g., to build for Raspberry Pi 4 on a Ubuntu 20.04 build system, you can use the following example. See [`build.yml` ](../../tree/main/.github/workflows/build.yml ) for complete build steps that create versions for Raspberry Pi 1, 2, 3,and 4 in 32-bit and 64-bit as required.
```
# Choose your RPi
export RPI=4
git clone https://github.com/probonopd/MiniDexed
cd MiniDexed
mkdir -p kernels sdcard
# Recursively pull git submodules
git submodule update --init --recursive
# Install toolchain
if [ "${RPI}" -gt 2 ]
then
wget https://developer.arm.com/-/media/Files/downloads/gnu-a/10.3-2021.07/binrel/gcc-arm-10.3-2021.07-x86_64-aarch64-none-elf.tar.xz
else
wget https://developer.arm.com/-/media/Files/downloads/gnu-a/10.3-2021.07/binrel/gcc-arm-10.3-2021.07-x86_64-arm-none-eabi.tar.xz
fi
tar xvf gcc-arm-*-*.tar.xz
export PATH=$(readlink -f ./gcc-*/bin/):$PATH
# Build dependencies and MiniDexed
./build.sh
cp ./src/kernel*.img ./kernels/
# Get Raspberry Pi boot files
cd ./circle-stdlib/libs/circle/boot
make
if [ "${RPI}" -gt 2 ]
then
make armstub64
fi
cd -
# Make zip that contains Raspberry Pi 4 boot files. The contents can be copied to a FAT32 formatted partition on a microSD card
cd sdcard
../getsysex.sh
cd ..
cp -r ./circle-stdlib/libs/circle/boot/* sdcard
rm -rf sdcard/config*.txt sdcard/README sdcard/Makefile sdcard/armstub sdcard/COPYING.linux
cp ./src/config.txt ./src/minidexed.ini ./src/*img ./src/performance.ini sdcard/
echo "usbspeed=full" > sdcard/cmdline.txt
cd sdcard
cp ../kernels/* . || true
zip -r ../MiniDexed_$GITHUB_RUN_NUMBER_$(date +%Y-%m-%d).zip *
cd -
# Optionally, create a RPi image. This can be written to a microSD card using tools like Etcher or dd
sudo apt install --yes mount parted
IMG="`date +%Y-%m-%d`_minidexed-RPi${RPI}.img"
dd of="${IMG}" seek=50MiB bs=1 count=0
sudo parted "${IMG}" mktable msdos
sudo parted "${IMG}" mkpart primary fat32 2048s 100%
DEV=`sudo losetup --find --partscan --show "${IMG}"`
sudo mkfs.vfat -F 32 -n BOOT "${DEV}p1"
mkdir boot
sudo mount "${DEV}p1" boot
sudo cp -R sdcard/* boot
sudo umount boot
sudo losetup -d "${DEV}"
rm -r boot
# Write to SD card
sudo dd if="${IMG}" of=/dev/mmcblk0 bs=512k status=progress
```
## Acknowledgements
* [asb2m10 ](https://github.com/asb2m10/dexed ) for the [Dexed ](https://github.com/asb2m10/dexed ) sound engine
* [dcoredump ](https://github.com/dcoredump ) for https://codeberg.org/dcoredump/Synth_Dexed, a port of Dexed for embedded systems
* [rsta2 ](https://github.com/rsta2 ) for https://github.com/rsta2/circle, the library to run code on bare betal Raspberry Pi (without a Linux kernel or operating system) and for the initial MiniDexed code
* [smuehlst ](https://github.com/smuehlst ) for https://github.com/smuehlst/circle-stdlib, a version with Standard C and C++ library support
