Headless MiniDexed on Zero 2W

[BobanSpasic]

Hi folks.
Here is my minimalistic MiniDexed (USB Gadget mode) based on just 3 components from Amazon:

• Raspberry Pi Zero 2 W: https://www.amazon.de/dp/B09KLVX4RT
• Addon Board V1.1: https://www.amazon.de/dp/B07NNS36TS
• PCM5102 DAC: https://www.amazon.de/dp/B07VKQKT9H (here are two pieces contained in the price)

Glued the PCM5102 to the board by using hot glue and two plastic standoffs:

Here is my minidexed.ini:

#
# minidexed.ini for headless Pi Zero 2W
#

USBGadget=1

# Sound device
SoundDevice=i2s
SampleRate=48000
DACI2CAddress=0
ChannelsSwapped=0
EngineType=1

# MIDI
MIDIBaudRate=31250
IgnoreAllNotesOff=0
MIDIAutoVoiceDumpOnPC=0
HeaderlessSysExVoices=0

# Program Change enable
MIDIRXProgramChange=1

# Program Change mode
ExpandPCAcrossBanks=1

# Program Change action:
PerformanceSelectChannel=16

# HD44780 LCD
LCDEnabled=0
LCDPinEnable=17
LCDPinRegisterSelect=4
LCDPinReadWrite=0
LCDPinData4=22
LCDPinData5=23
LCDPinData6=24
LCDPinData7=25
LCDI2CAddress=0x00

# SSD1306 LCD
SSD1306LCDI2CAddress=0x0
SSD1306LCDWidth=128
SSD1306LCDHeight=32
SSD1306LCDRotate=0
SSD1306LCDMirror=0

# ST7789 LCD
SPIBus=
ST7789Enabled=0
ST7789Data=
ST7789Select=
ST7789Reset=
ST7789Backlight=
ST7789Width=240
ST7789Height=240
ST7789Rotation=0
ST7789SmallFont=0

# Default is 16x2 display (e.g. HD44780)
LCDColumns=16
LCDRows=2

# GPIO Button Navigation
#  Any buttons set to 0 will be ignored
ButtonPinPrev=0
ButtonActionPrev=
ButtonPinNext=0
ButtonActionNext=
ButtonPinBack=0
ButtonActionBack=
ButtonPinSelect=0
ButtonActionSelect=
ButtonPinHome=0
ButtonActionHome=
ButtonPinShortcut=0
# (Shortcut doesn't have an action)

# GPIO Program/TG Selection
#  Any buttons set to 0 will be ignored
ButtonPinPgmUp=0
ButtonActionPgmUp=
ButtonPinPgmDown=0
ButtonActionPgmDown=
ButtonPinTGUp=0
ButtonActionTGUp=
ButtonPinTGDown=0
ButtonActionTGDown=

# Timeouts in milliseconds for double click and long press
DoubleClickTimeout=400
LongPressTimeout=400

# MIDI Button Navigation
MIDIButtonCh=0
MIDIButtonNotes=0
MIDIButtonPrev=0
MIDIButtonNext=0
MIDIButtonBack=0
MIDIButtonSelect=0
MIDIButtonHome=0
MIDIButtonPgmUp=0
MIDIButtonPgmDown=0
MIDIButtonTGUp=0
MIDIButtonTGDown=0

# KY-040 Rotary Encoder
EncoderEnabled=0
EncoderPinClock=10
EncoderPinData=9

# Debug
MIDIDumpEnabled=0
ProfileEnabled=0

# Performance
PerformanceSelectToLoad=1

[probonopd]

Wow, that's a pretty neat minimalistic setup. I like it 👍

[Kirtai]

Very cool. Is it using pogo pins to make the connection?

[BobanSpasic]

Spring contacts. Something like this https://images.app.goo.gl/Pz2G7m6h6iMUnvVX7
I was suspicious about the quality, but no problems to date.
My only problem with this Zero 2 W was just the same as with my other MiniDexeds - finding a SD Card that works. I have some 2GB SD Cards that aren't working with any MiniDexed, but are OK in other devices.

[Kirtai]

Yeah, those are similar to what I was thinking. Thanks :)

[Kirtai]

Oh, does it also need external power or does it just need to be plugged into a USB host port?

[BobanSpasic]

It is built as a USB Gadget - it means "for computers only". It doesn't need external power. In the fact, you must not connect external power if it is in USB Gadget mode (you will short-circuit the external and USB power lines).
It will appear as a new MIDI Synth on your PC, ready to use in your DAW.

[Kirtai]

Thanks, the adapter arrived today so now I'm off to try it :)

[blixabloxa]

I might try making one of these - looks like a great gadget to plug into the laptop with a DAW and head phones. How do you control it via your DAW? Do you use an INS file or similar to change the performances?

[BobanSpasic]

I use one performance with TGs set to MIDI channels 1-8. I change the voices in the TGs, but didn't change the performances.

[Alan-Angel]

I've done something similar although I wasn't brave enough to risk mechanical stress on the usb port by not using a cable.

[diyelectromusic]

By the way if you want a soldered USB solution I can recommend the USB ZeroSTEM (https://zerostem.io/installation/) it is what I used with my Zero PCBS (https://diyelectromusic.com/2023/12/02/rpi-zero-minidexed-io-board-pcb-design/).

Kevin