CC-BY 3.0
(still work in progress, not fully tested)
A smart MIDI box based on a STM32 "blue pill" microcontroller (STM32F103C8T6).
Software is hosted on Github: https://github.com/retro16/MidiBox
Uses a HD44780 16x2 LCD screen with the usual I2C converter.
The interface is made of 4 push buttons arranged in a directional pad (up, down, left, right).
A SD card can be attached for more features.
Some parts on the PCB are optional, depending on what you wish to do with the board.
J1 and J2 are only useful for port extenders so it's useless to put them on the main board.
J3 places the firmware in extender mode so it must be omitted on the main board.
If you remove the SD card, the LCD screen and buttons, all MIDI messages will be routed to the first MIDI output. It acts like a buffered MIDI merger.
MIDI port extenders can be used in that configuration.
If you omit the SD card, you can omit C2 (decoupling capacitor).
ID | Name | Designator | Footprint | Quantity |
---|---|---|---|---|
1 | POWER | P1 | HDR-TH_2P-P2.54-V-M | 1 |
2 | MUX | P2 | HDR-TH_2P-P2.54-V-M | 1 |
3 | 1N4448 | D1,D2 | DO-35 | 2 |
4 | BC547B | Q1,Q2,Q3,Q4 | TO-92_3PIN-L4.95-W3.94-PITCH2.54-L | 4 |
5 | MIDI1 IN | H2 | HDR-TH_3P-P2.54-V | 1 |
6 | MIDI1 OUT | H4 | HDR-TH_3P-P2.54-V | 1 |
7 | MIDI2 IN | H5 | HDR-TH_3P-P2.54-V | 1 |
8 | MIDI2 OUT | H6 | HDR-TH_3P-P2.54-V | 1 |
9 | 100u | C1 | 1206 | 1 |
10 | BTN | H1 | HDR-5X1/2.54 | 1 |
11 | 6N137EE | U1,U3 | DIP8 | 2 |
12 | STM32F103 | U2 | STM32F103C8 | 1 |
13 | LCD | H3 | DIP-1X4P2.54 | 1 |
14 | 100n | C2 | 0805 | 1 |
15 | GATES | P3 | HDR-8X1/2.54 | 1 |
16 | SD | P4 | HDR-8X1/2.54 | 1 |
17 | ULN2803AN | U4 | DIP18 | 1 |
18 | 10k | R13,R14,R15,R16,R17,R18,R19,R20,R3,R1,R6,R9,R7,R12 | 0805 | 14 |
19 | 220 | R2,R4,R5,R8,R10,R11 | 0805 | 6 |
20 | ADDR_H | J1 | 0805 | 1 |
21 | ADDR_M | J2 | 0805 | 1 |
22 | EXT_EN | J3 | 0805 | 1 |
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