Kicad-MidiToCV

Midi to CV in Eurorack or as standalone

Status - Rev B - Ongoing PCB layout and Sch update

Set on hold - MK2 is in progress ATM

Status - Rev A Mounted - Midi code in progress

Stage	Detail	Status
create material	sch/pcb	produced Rev A
	gerber	produced and uploaded RevA
production	ordered	OK
	produced	OK
	delivered	OK
-------------	-------------	-------------
SOFTWARE	LFO	OK
SOFTWARE	MIDI MAP	OK - Stage 1
SOFTWARE	CV	Ongoing

Preliminary validation

Test	Detail	Status
Initial Inspection	Visual - Component Mounting	NOT OK
Initial Technical Test	Base operation	MIDI OUT NOT OK
	Knobs	OK
Initial Technical Test	MIDI IN	OK
Initial Technical Test	MIDI OUT	OK (to USB adapter)
Initial Product Test	MIDI IN/OUT MAPPER	OK
Initial Product Test	MIDI IN / CV OUT / GATE OUT	OK
Initial Product Test	LFO OUT	OK (use different pinout)

Secondary validation

Test	Detail	Status
Product Test	MIDI IN/OUT	OUT - FAIL on Roland keyboard
Product Test	LFO on DIO6 and 9 with ext RC	OK !
Quality	LFO	Very usable
Quality	MIDI IN
Quality	MIDI to CV
Quality	MIDI to GATE
Long Term Product Test	MIDI IN
Long Term Product Test	CV OUT
Long Term Product Test	GATE OUT
Long Term Product Test	LFO OUT	OK

Issues and Notes

Please note that the PIN1 and PIN2 are GATE. This is note described clearly in http://www.doepfer.de/a100_man/a100t_e.htm and needs to be noted when soldering the IDC header or when cabling if a Pin header has been mounted.

The two pots on the breakout board are too close for adding a knob
The orientation of the pinheader for the MCP4725 module - if mounted incorrectly the magic smoke disappears
0R could be replaced with SMD jumpers
Consider a 200 mA fuse for Vin and 50mA for +5V pwr
The mounting hole that is off center is not matching both boards

Errata

Footprint of PJ-321 has too small drill holes (1mm) - major
Footprint of PJ-321 is too narrow in the rear end :) - minor issue
Midi out circuit is WRONG - Major

Workarounds

Midi out not working - PCB workaround mod partially possible for voltage controlled inputs.
--Remove GND around DIN pin 5 (bottom copper side)
--Cut GND track to DIN pin 5 (top copper side)
--Remove Q1, R6, R9
--Connect 220R THT to base pad on Q1
--Connect C and E on Q1
--Add GND wire to pin2 of MIDI out DIN

Physical Construction

100x100mm
Separate unit with no alteration
Optional split in 2 for eurorack mount mirrored config

Vital Components

Arduino Nano - where the magic lives (remember to socket it to be able to reprogram it)
Jack connectors: PJ-321 (important for the footprint)
KY-40 Encoder module (important for the pullup, footprint and 3D alignment)
MCP4825 module - if chosen (important for CV out function - footprint needs to match) If these are chosen the last two CV jacks should be ommitted.
MCP4728 chip - if chosen (important for the last 2 CV out)

MIDI Board Features

Single board - MIDI I/O and MIDI to CV

The board can be used as is for a prototype development of MIDI to CV

Split board Eurorack - MIDI I/O and MIDI to CV

The board can be devided in two and combined front to front with spacers for a MIDI to CV eurorack module.

Base board Eurorack - MIDI I/O

If only MIDI features are required the base board can work without the IO section.

Generic Board Features

Split board Options

The main board (with the arduino) has a couple of headers that can be connected to a different interface board using I2C, Analogue Inputs and Digital I/O.

Non MIDI board

The MIDI components can be omitted if the features does not require MIDI, like an LFO, VCO or ADSR circuit.

Base Construction

Arduino Nano based Controller and MIDI decoder.

MIDI In

MIDI In through a PC814 (or optional PC817) Optocoupler and into the RX pin on the Arduino

Midi Out

Optional expansion

Gate

Gate pins from Arduino

CV Out

I2C Dac with 2 options

I2C Dac - Option 1 - Two Single channel DAC

2x MCP4725 DAC

I2C Dac - Option 2 - One 4 channel DAC

1x MCP4728

promesoft/KicadJE-MidiToCV