HardLabs

Brain board

FrankBuss·beat707·kicad/beat707/brain-board.kicad_pcb

Brain board layout, top view — open source AVR/Arduino board by FrankBuss

About the Brain board

Brain board is an open source AVR/Arduino PCB design by FrankBuss, published on GitHub. It is a 2-layer board measuring 100 × 100 mm, with 70 components from 28 distinct parts.

Its main chip is the ATmega328-PU, from the AVR/Arduino family. Other key parts include the 6N138, 74HC14, SN74AHC125, MB85RS2MT and LP2950CZ-3.3G. By type, the board carries 33 resistors, 11 capacitors, 9 connectors, 7 ICs, 5 diodes and 4 switches.

It belongs with the audio designs in this gallery.

From the project

A MIDI sequencer

For programming you can use an USBasp. The red wire of the USBasp programmer needs to be connected to the pin 1 location:

For debugging, there is the jumper J5 near the MIDI connector, to connect a 5V UART receiver. Connect the top pin to GND (black wire in the image) and the bottom pin to the UART RX input (grey wire) :

The Arduino IDE doesn't flash the ATmega fuses, so initially you need to do this from the command line with avrdude like this:

Brain board, from the project README
From the project README

Main components on the Brain board

6N13874HC14ATmega328-PUSN74AHC125MB85RS2MTLP2950CZ-3.3GSN74AHCT125

Brain board bill of materials (BOM)

70 components, 28 distinct parts.

QtyPartRefs
1
6N138
U1
1
74HC14
U2
1
ATmega328-PU
U3
1
SN74AHC125
U4
1
MB85RS2MT
U5
1
LP2950CZ-3.3G
U6
1
SN74AHCT125
U7
1
20 MHz
Y1
1
footswitch
J1
1
click-out
J2
1
MIDI-in
J3
1
MIDI-out
J4
1
USB_B
J5
1
Conn_01x07
J6
1
free IO
J7
1
ISP
J8
1
Conn_01x02_Male
J9
1
Rotary_Encoder_Switch
SW1
3
SW_Push
SW2, SW3, SW4
5
1N4148
D1, D2, D3, D4, D5
Show 8 more
QtyPartRefs
6
100nF
C1, C4, C5, C6, C9, C10
2
1nF
C2, C3
2
22pF
C7, C8
1
10uF
C11
6
220
R1, R2, R5, R6, R8, R9
4
1k
R3, R21, R22, R23
10
10k
R4, R7, R10, R11, R17, R18, R19, R20 +2
13
33
R12, R13, R14, R15, R16, R25, R26, R28 +5

Brain board design files

The KiCad project lives in the FrankBuss/beat707 repository on GitHub; these links point at the commit this page was built from.

Brain board: common questions

What microcontroller does the Brain board use?

The Brain board is built around the ATmega328-PU, from the AVR/Arduino family.

How big is the Brain board?

The Brain board measures 100 × 100 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Brain board?

70 components, from 28 distinct parts. The full bill of materials is listed on this page.

Where can I download the Brain board design files?

From the FrankBuss/beat707 repository on GitHub, which has the KiCad layout; the links under Design files point to each one.

Can I use the Brain board design in my own project?

The repository has no license, so all rights stay with FrankBuss. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the Brain board 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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