The software was placed in the public domain by the author, Yukimizake in 2012.

I have refactored the code so it compiles on the latest Arduino IDE

Special thanks to Obakegaku who has really kept the wheels moving on this project with his advice, input and enthusiasm. A video of him in action!

If you feel you can add to the knowledge or just have a question send us an email
We appreciate all input


5 Pin Din MIDI 3.5mm MIDI
Use one or the other of the MIDI inputs
The 3.5mm MIDI socket is type A

1 note per midi channel
To a maximum of three notes at once
It can also play 4bit samples.

Audio Out
Switchable between mono jack and stereo jack.
Although a stereo Jack will give you the same signal on left and right.
A volume knob

What does it sound like ?

First Release Version 2.1 MIDI IN YM2149F Complete
OLED PCB v2.1a October 2022 MIDI IN YM2149F OLED PCB v2.1a Latest PCB v2.1a October 2022 MIDI IN YM2149F PCB v2.1a PCB v2.1 MIDI IN YM2149F PCB v2.1

Acrylic Covers by LaserLab in Bristol MIDI IN YM2149F PCB

Built v2.1 MIDI IN YM2149F built
High Resolution Image
Newest version includes:-
• A volume knob
• A 3.5mm Type A MIDI In
• A decent PCB mounted DC power socket
• A switch to select Mono or Stereo jack
• A programming socket for the
CP2102 USB to TTL adaptor.


Code / Artwork / Libraries

Arduino IDE
  v2.1 1st May 2022
  v2.1a 21st Oct 2022
Download Arduino IDE

Fritzing PCB File
Editable PCB Files by dansfing.uk
01/05/22 v2.1 fzz
21/10/22 v2.1a fzz

Production PCB
GERBER PCB Files by dansfing.uk
01/05/22 v2.1 zip
21/10/22 v2.1a zip

Laser Cutting Files for panels

Panels For blk v2 PCB
Desktop Format

Original Concept
by yukimizake 2012
Top tastic maker skills.
Assembly Guide

Assembly Instructions - English
High Resolution Image
Arduino Upload Guide


Print List
1 x

1 x
Tone Generator

1 x
Clock Divider

1 x
Opto Isolator

1 x
8Mhz Oscillator
DIP 14

1 x
16Mhz Crystal

1 x
5v Regulator

1 x
Signal Diode

2 x
3mm LED
Activity and power LEDs

2 x
10uF Electrolytic Capacitors
25v or more

1 x
100uF Electrolytic Capacitor
25v or more

1 x
1uF Electrolytic Capacitor
25v or more

3 x
100nF Polyester Capacitor
box style or ceramic

1 x
4.7nF Polyester Capacitor
box style or ceramic

2 x
22pF ceramic Capacitors

3 x
470 Ohm Resistors

1 x
220 Ohm Resistor

1 x
1K Ohm Resistor

2 x
10K Ohm Resistor

1 x
100K Ohm Resistor

1 x
5 pin din socket

2 x
3.5mm Stereo jack socket

1 x
2.5mm DC Power Socket

1 x
5 Pin 90 degree female board to board connector

1 x
5mm Push botton
For reset

2 x
2.54 Switch SPST

Circuit Diagram

MIDI IN YM2149F Circuit Diagram
The circuit diagram was posted by Mr Megahertz in May 2012 Original Post

New firmware 2.1a adds...
OLED Screen on i2c
Fixes MIDI Channel 7
Use of timer driven interrupts
There are 6 analogue pins for expansion. These include i2c pins so you can drive an OLED display using only 2 wires.
Leaving you with four analogue pins for knobs or buttons. We can listen every now and again to see if a button has been pressed.
Adding an i2C OLED Display

Latest OLED firmware.
   Version 2.1a    21st Oct 2022

Add the graphics library in Arduino IDE
(1) Click Sketch Menu
(2) Hover mouse on Include Library
(3) and click on Library Manager
(4) Wait for it to update then search u8x8
(5) Install U8g2 Library
(6) Try to compile code, if successful upload.
(a) Screen remains blank until it hears MIDI.
(b) Screen blanks after 2 minutes of no MIDI.
(b) Sample playback shows on right of screen

What does it look like ?
Wiring the i2C OLED Display

There are 2 main types using different chips.
SSD1306 and SH1106
Uncomment the type you have in code - view code.

4 pin i2C OLED 128x64
(•) Ground
(•) +5v
(•) SDA - i2c Data
(•) SCL - i2c Clock / SCK
Check your screen pinout and wire each pin to the following pins on the Synth
Synth 2.1            OLED
 +                     VCC
 -                    GND
 A0                    SCL / CLK / SCK
 A5                    SDA / Data

Synth 2.1a            OLED
 +                     VCC
 -                    GND
 A5                    SCL / CLK / SCK
 A4                    SDA / Data
Noises from contributers

Andy in Bedford UK @Obakegaku peforing a live stream, Flash Crash
Noises from contributers

You can also buy it here

YM2149F TRS MIDI Synthesiser by dansfing.uk


Buy now