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C64UserPortMidi

relic-se·C64UserPortMidi·hardware/C64UserPortMidi.kicad_pcb

C64UserPortMidi PCB layout, top view — open source AVR/Arduino board by relic-se

About the C64UserPortMidi PCB

C64UserPortMidi is an open source AVR/Arduino PCB design by relic-se, published on GitHub under the GPL-3.0 license. It is a 2-layer board measuring 62.5 × 47.5 mm, with 25 components from 19 distinct parts.

Its main chip is the ATTINY2313-20P, from the AVR/Arduino family. Other key parts include the 6N138. By type, the board carries 7 resistors, 4 connectors, 4 capacitors, 3 test points, 2 ICs and 2 jumpers.

It belongs with the retro computing and audio designs in this gallery.

From the project

Simple MIDI input and output interface using Commodore 64 user port. Utilizes an ATtiny2313 microcontroller and 6n138 opto-isolator.

I found myself in possession of a Commodore SX-64 and a desire to make music with it. After quickly finding Cynthcart, I wasn't too happy about the idea of plugging both the Cynthcart cartridge and a separate Datel midi cartridge into in a Mini X-Pander+ all sticking out of the hood of my SX-64. I had assumed that the User Port would have been a great interface for transmitting the necessary midi input data to whatever SID program you're jamming with. That's where this project comes in.

C64UserPortMidi, from the project README
From the project README

Main components on the C64UserPortMidi

ATTINY2313-20P6N138

C64UserPortMidi bill of materials (BOM)

25 components, 19 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
ATTINY2313-20P
ATtiny2313-20P
U1
1
6N138
U2
1
2N3904
Q1
1
C64-USERPORT
C64-UserPort
J1
1
MIDI IN
J2
1
AVR-ISP-6
J3
1
MIDI OUT
J4
1
MIDI Output Bypass
JP1
1
RST Bypass
JP2
1
PD4
TP1
1
PD6
TP3
1
PA2
PC2
TP4
1
1N914
D1
1
LED
D2
3
0.1UF
0.1uF
C1, C2, C3
1
10UF
10uF
C4
5
220
R1, R2, R4, R5, R6
1
4.7K
4.7k
R3
1
10K
10k
R7

C64UserPortMidi design files

The KiCad project lives in the relic-se/C64UserPortMidi repository on GitHub; these links point at the commit this page was built from.

C64UserPortMidi: common questions

What microcontroller does the C64UserPortMidi use?

The C64UserPortMidi is built around the ATTINY2313-20P, from the AVR/Arduino family.

How big is the C64UserPortMidi PCB?

The C64UserPortMidi measures 62.5 × 47.5 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the C64UserPortMidi?

25 components, from 19 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the C64UserPortMidi design files?

From the relic-se/C64UserPortMidi repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the C64UserPortMidi design in my own project?

Yes, under the terms of its GPL-3.0 license, which relic-se chose for the repository.

Can I test firmware for the C64UserPortMidi without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug AVR/Arduino firmware against it before you order a PCB.

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