HardLabs

SmallKat CM4

keionbis·SmallKat_CM4

SmallKat CM4 PCB layout, top view — open source ESP32 board by keionbis
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About the SmallKat CM4 PCB

SmallKat CM4 is an open source ESP32 PCB design by keionbis, published on GitHub. It is a 4-layer board measuring 100 × 56 mm, with 152 components from 65 distinct parts.

Its main chip is the ESP32-WROOM-32, from the ESP32 family. Other key parts include the LMR50410YQDBVRQ1, TLVM13630, TPS40192DRCT, PCA9685BS and BNO055. By type, the board carries 47 resistors, 36 capacitors, 30 connectors, 14 diodes, 9 ICs and 6 fuses.

From the project

i2c 1 (SCL 22, SDA 21) - BNO055, QwIIC connector i2c 2 (SCL 27, SDA 32) - PCA9685

Main components on the SmallKat CM4

LMR50410YQDBVRQ1TLVM13630TPS40192DRCTPCA9685BSBNO055ESP32-WROOM-32CP2102N-A01-GQFN24ISM330DLCTRSTM32G474CEU6

SmallKat CM4 bill of materials (BOM)

152 components, 65 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
LMR50410YQDBVRQ1
LMR14010A
IC1
1
TLVM13630
IC2
1
TPS40192DRCT
TPS40192DRCT-TPS40192DRCT
IC3
1
PCA9685BS
U1
1
BNO055
U2
1
ESP32-WROOM-32
74LVC1G07
U3
1
CP2102N-A01-GQFN24
FSUSB42MX
U4
1
ISM330DLCTR
U5
1
STM32G474CEU6
U6
2
BUK9M17-30EX / BUK7M10-40E
Q2, Q3
1
32.768KHZ
32.768kHz
Y1
1
Crystal_GND24_Small
Y2
1
Crystal_Small
Y3
6
1568-PRT-16766
Qwiic connector
J1, J2, J26, J27, J28, J29
20
CONN_01X03_MALE
Conn_01x03_Male
J3, J4, J5, J6, J9, J10, J11, J12 +12
1
Conn_01x22_Female
J8
1
Conn_01x02_Female
J25
1
HDMI_A_1.4
J30
1
USB_C_Receptacle
J31
5
Fuse
F1, F2, F3, F4, F5
Show 45 more
QtyPartRefs
1
Fuse
F6
1
ComputeModule4-CM4
Module1
2
SW_SPST
SW1, SW2
11
LED
D1, D2, D3, D5, D6, D7, D9, D10 +3
1
DIODE
D4
2
D_TVS
D8, D14
1
10UH
10uH
L1
1
1UH
1uH
L3
4
0.1UF
0.1uF
C1, C12, C14, C22
1
2.2UF
2.2uF
C2
2
0.1UF
C
C3, C21
1
10UF
10uF
C4
1
2.2UF
C
C5
1
10UF
C
C6
6
C
C7, C8, C9, C10, C11, C13
2
10PF
10pF
C15, C16
1
22UF
C
C17
1
0.1UF
C
C18
1
4.7UF
C
C19
2
0.1UF
C
C20, C23
1
1000PF
1000pF
C24
1
100PF
100pF
C25
1
10NF
10nF
C26
2
1UF
1uF
C27, C36
1
4.7UF
4.7uF
C28
1
470NF
470nF
C29
2
10UF
10uF
C30, C32
2
47UF
47uF
C31, C34
2
100UF
100uF
C33, C35
2
330R
R1, R16
14
10K
R2, R4, R7, R10, R14, R17, R19, R20 +6
1
2.4K
R3
6
8.2K
R5, R8, R25, R28, R31, R34
1
120K
R6
6
20K
R9, R26, R29, R32, R35, R37
1
33.2K
R
R11
1
33.2K
33.2
R12
6
10K
R
R13, R18, R21, R22, R23, R44
2
R
R15, R47
1
2.18K
2.18k
R36
1
2.61K
2.61k
R38
1
4.22K
4.22k
R39
1
12K
12k
R40
2
100K
100k
R41, R42
1
1K
R43

SmallKat CM4 design files

The KiCad project lives in the keionbis/SmallKat_CM4 repository on GitHub; these links point at the commit this page was built from.

SmallKat CM4: common questions

What microcontroller does the SmallKat CM4 use?

The SmallKat CM4 is built around the ESP32-WROOM-32, from the ESP32 family.

How big is the SmallKat CM4 PCB?

The SmallKat CM4 measures 100 × 56 mm, has 4 copper layers and is 4.48 mm thick.

How many components are on the SmallKat CM4?

152 components, from 65 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 SmallKat CM4 design files?

From the keionbis/SmallKat_CM4 repository on GitHub, which has the KiCad layout and the BOM; the links under Design files point to each one.

Can I use the SmallKat CM4 design in my own project?

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

Can I test firmware for the SmallKat CM4 without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug ESP32 firmware against it before you order a PCB.

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