HardLabs

UsbSound

SteveSyfuhs·UsbSound

UsbSound PCB layout, top view — open source STM32 board by SteveSyfuhs

About the UsbSound PCB

UsbSound is an open source STM32 PCB design by SteveSyfuhs, published on GitHub under the MIT license. It is a 4-layer board measuring 121.6 × 79.8 mm, with 91 components from 43 distinct parts.

Its main chip is the STM32F405RGT6, from the STM32 family. Other key parts include the XRP7659, ICL7660, USBLC6-2SC6, NE5534 and PCM1795DB. By type, the board carries 45 capacitors, 20 resistors, 9 ICs, 5 connectors, 4 diodes and 4 inductors.

It belongs with the audio designs in this gallery.

From the project

A custom-made USB sound card for Balanced Audio

My current USB DAC isn't great and instead of just buying a new one I thought I'd try and waste some serious engineering hours learning how to build one instead.

My existing DAC uses the PCM2705 chip to handle both the USB and DAC side of things. It's fine, I guess, but it has some annoying quirks.

First, you have to bolt on an additional chip to do silly things like control the USB descriptors. Absent that you're left with this annoying string with two trailing spaces (probably nulls?). Clearly not the end of the world, but I might as well aim for perfect.

UsbSound, from the project README
From the project README

Main components on the UsbSound

XRP7659ICL7660USBLC6-2SC6NE5534PCM1795DBSTM32F405RGT6

UsbSound bill of materials (BOM)

91 components, 43 distinct parts.

QtyPartRefs
1
XRP7659
U1
1
ICL7660
U2
1
USBLC6-2SC6
U3
4
NE5534
U4, U7, U8, U9
1
PCM1795DB
U5
1
STM32F405RGT6
U6
1
16MHz
Y1
1
36.864MHz
Y2
2
SWD
J1, J5
1
USB_B
J2
1
XLR_L
J3
1
XLR_R
J4
1
250mA
F1
1
BOOT_SELECT
SW1
2
B5819W
D1, D2
2
Red
D3, D4
1
600 @ 600MHz
FB1
1
10u
L1
1
39n
L2
1
39n
L3
Show 23 more
QtyPartRefs
10
10u
C1, C2, C3, C4, C5, C6, C32, C34 +2
4
2700pF
C7, C23, C33, C42
2
1u
C8, C16
2
10n
C9, C17
8
0u1
C10, C20, C24, C30, C39, C41, C43, C45
1
4u7
C11
4
100n
C12, C13, C14, C15
1
47u
C18
4
22pF
C19, C27, C40, C44
2
2u2
C21, C22
4
12p
C25, C26, C28, C29
3
0.1u
C31, C35, C37
1
47k
R1
1
15k
R2
1
270
R3
1
100k
R4
1
68k
R5
4
820
R6, R13, R16, R19
2
2k2
R7, R20
2
10k
R8, R12
3
27
R9, R10, R11
2
0
R14, R15
2
4k7
R17, R18

UsbSound design files

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

UsbSound: common questions

What microcontroller does the UsbSound use?

The UsbSound is built around the STM32F405RGT6, from the STM32 family.

How big is the UsbSound PCB?

The UsbSound measures 121.6 × 79.8 mm, has 4 copper layers and is 4.69 mm thick.

How many components are on the UsbSound?

91 components, from 43 distinct parts. The full bill of materials is listed on this page.

Where can I download the UsbSound design files?

From the SteveSyfuhs/UsbSound repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the UsbSound design in my own project?

Yes, under the terms of its MIT license, which SteveSyfuhs chose for the repository.

Can I test firmware for the UsbSound without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug STM32 firmware against it before you order a PCB.

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