MIDIbox Hardware Platform, MIDI_IO Module

MBHP_MIDI_IO is a MIDI breakout board for the MBHP_CORE_STM32F4 module.

It consists of two MIDI IN/OUT pairs and MIDI Activity LEDs which are connected to monoflops.

The input socket J1 has to be connected to J11E of the MBHP_CORE_STM32F4 module. J1 of a second MBHP_MIDI_IO can be connected to J2 in order to get 4 MIDI INs/OUTs in total. More modules can't be chained (4 IN/OUT ports maximum).

This approach has the advantage, that the builder can decide by himself, if - and how many - MIDI IOs he wants to add to his MIDIbox.

Note that the MIDI activity indicators are only an optional feature. The circuit will also work without the circuit around the 74HC00 ICs (see schematic).

Download

Module	Schematic	Layout Data	Quick-view
MBHP_MIDI_IO_V1	mbhp_midi_io.pdf	to be published	mbhp_midi_io_0.jpg

Additional informations
File	Size	Description
mbhp_midi_io_orderlist.txt	1k	Reichelt orderlist

Available Ports

Following interfaces are provided by the MBHP_MIDI_IO module:

Name	No. of pins	Description
J1	10	Connection to J11E of the MBHP_CORE_STM32F4 module, resp. to J2 of a second MBHP_MIDI_IO module (to get 4 MIDI IN/OUT ports)
J2	10	Connection to J2 of the first MBHP_MIDI_IO module in the chain to get 4 MIDI IN/OUT ports in total.
J3-J6	2	Optional MIDI Activity LEDs

Soldering Guide

	It's always a good idea to start with the smallest components to simplify mounting. So, start with the resistors and diodes: R1, R3, R5, R6, R8, R10, R11, R13, R15, R17 = 220 Ohm R4, R9 = 1k R2, R7 = 4.7k R12, R14, R16, R18, R19, R20 = 100k D1, D2 = 1N4148
	Continue with caps and LEDs: C1, C2 = 100 nF C3, C4, C5, C6 = 10 uF (El.Caps - polarity! Plus leg show to border) the 4 LEDs at J3..J6 don't need sockets. Take care for the polarity! Anode (the long leg) shows to the right side!
	Mount the IC sockets
	And then the DIL Headers and MIDI Sockets
	And finally put the ICs into the sockets: IC1, IC2 = 6N138 IC3, IC4 = 74HC00

Two MBHP_MIDI_IO modules connected to J11E of the MBHP_CORE_STM32F4 module in a chain.

Board Modification for 3.3V based MIDI outputs

If you are planning to use this module for a microcontroller which outputs MIDI OUT at 3.3V level (such as the MBHP_CORE_LPC17 module), please change the R3, R5, R8 and R10 resistor values to 47 Ohm, and connect J1:Vd to 3.3V instead of 5V!
This measure is not required for microcontrollers which output 5V, or where MIDI output (Tx) pins can be configured in open drain mode.

Credits

Thanks to Tim aka. SmashTV for the great idea to chain two MBHP_MIDI_IO modules by using a special J1/J2 pin encoding. He also created the PCB layout. PCBs are available in Modular Addict's MIDIbox Shop.

Copyright © 1998-2023, Thorsten Klose. All rights reserved.