HardLabs

Digital board

minisystem·MonApollo

Digital board layout, top view — open source AVR/Arduino board by minisystem

About the Digital board

Digital board is an open source AVR/Arduino PCB design by minisystem, published on GitHub. It is a 2-layer board measuring 200 × 150 mm, with 237 components from 65 distinct parts.

Its main chip is the ATMEGA6450-A, from the AVR/Arduino family. Other key parts include the DG419, 74HC4067, R-78E5.0-1.0, 74LS573 and 74LVC2G04. By type, the board carries 91 resistors, 30 LEDs, 26 capacitors, 16 ICs, 9 switches and 7 test points.

From the project

Programmable Monosynth Prototype

Digital board tested and working. SPI LED driving and switch reading tested. ADC pot reading but there is some cross-talk on potentiometer ADC channels. Allowing sufficient settling time at ADC node between reads seems to mostly remedy this to <= 1 LSB.

NOISE/LFO/S&H tested and working, except for multiplexer latch problem mentioned below. Noise gain needed to be adjusted by changing R180 to 10K and R181 to 750K (two 1.5M 0603s stacked in parallel). Also LFO module needede R3 (on module board) changed to 270K from 1M to get proper adjustment of sine/tri symmetry. Sine symmetry is too…

Main components on the Digital board

ATMEGA6450-ADG41974HC4067R-78E5.0-1.074LS57374LVC2G0474AC59574HC16574LVC1G32

Digital board bill of materials (BOM)

237 components, 65 distinct parts.

QtyPartRefs
1
ATMEGA6450-A
IC1
1
DG419
U1
2
74HC4067
U2, U4
1
R-78E5.0-1.0
U3
2
74LS573
U5, U6
1
74LVC2G04
U7
5
74AC595
U8, U12, U13, U15, U16
2
74HC165
U9, U14
1
74LVC1G32
U10
2
2N3904
Q1, Q2
1
MIDI OUT
X1
1
MIDI IN
X2
1
MIDI THRU
X3
1
CONN_20X2
J1
1
LDQ-M286R1
DS1
1
VAL**
HOLE-0.125-INCH
1
CONN_3X2
ISP1
14
TL1240
ISW1, ISW2, ISW3, ISW4, ISW5, ISW6, ISW7, ISW8 +6
1
6N137
OC1
9
TACT_SWITCH
SW15, SW16, SW17, SW18, SW19, SW20, SW21, SW22 +1
Show 45 more
QtyPartRefs
7
CONN_1
TP1, TP2, TP9, TP10, TP11, TP12, TP13
1
TUNE
VR1
1
VCO1 PW
VR2
1
PWM EG2
VR3
1
PWM LFO
VR4
1
PITCH LFO
VR5
1
PITCH VCO2
VR6
1
PITCH EG2
VR7
1
FINE
VR8
1
VCO2 PW
VR9
1
VCO1 MIX
VR10
1
VCO2 MIX
VR11
1
NOISE
VR12
1
FIL LFO
VR13
1
FIL VCO2
VR14
1
KEY TRACK
VR15
1
FIL EG2
VR16
1
CUTOFF
VR17
1
RES
VR18
2
ATTACK
VR19, VR27
2
DECAY
VR20, VR28
2
SUSTAIN
VR21, VR29
2
RELEASE
VR22, VR30
1
LFO RATE
VR23
1
ARP RATE
VR24
1
GLIDE
VR25
1
AMP LFO
VR26
1
VOLUME
VR31
1
20MHz
XTAL1
1
LED
LED2
29
LED
LED3, LED4, LED5, LED6, LED7, LED8, LED9, LED10 +21
1
1N4148
D1
1
10µH
L1
22
0.1µ
C1, C4, C5, C7, C9, C10, C11, C12 +14
2
24p
C2, C3
1
10µ
C6
1
2.2µ
C8
1
100K
R1
7
1K
R2, R3, R6, R21, R46, R47, R48
2
330
R5, R31
4
220
R7, R8, R13, R19
42
470
R9, R22, R23, R24, R25, R26, R27, R28 +34
7
560
R10, R11, R12, R14, R15, R16, R17
27
10K
R18, R30, R34, R36, R37, R40, R41, R44 +19
1
47K
R20

Digital board design files

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

Digital board: common questions

What microcontroller does the Digital board use?

The Digital board is built around the ATMEGA6450-A, from the AVR/Arduino family.

How big is the Digital board?

The Digital board measures 200 × 150 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Digital board?

237 components, from 65 distinct parts. The full bill of materials is listed on this page.

Where can I download the Digital board design files?

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

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

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

Can I test firmware for the Digital 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.

More boards in MonApollo

Similar boards