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ESP32 4-20mA Sensor

Diode663·ESP32_4-20mA_Sensor

ESP32 4-20mA Sensor PCB layout, top view — open source ESP32 board by Diode663
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About the ESP32 4-20mA Sensor PCB

ESP32 4-20mA Sensor is an open source ESP32 PCB design by Diode663, published on GitHub under the CERN-OHL-P-2.0 license. It is a 2-layer board measuring 40 × 61 mm, with 47 components from 35 distinct parts.

Its main chip is the ESP32-S3-WROOM-1U-N4, from the ESP32 family. Other key parts include the INA226AIDGSR, AP2112K-3.3TRG1 and MT3608. By type, the board carries 18 resistors, 10 capacitors, 5 diodes, 4 ICs, 4 transistors and 2 connectors.

It belongs with the iot & wireless and sensors designs in this gallery.

From the project

Single-channel industrial 4-20 mA current-loop reader for ESPHome / Home Assistant. ESP32-S3 + INA226, USB-C powered, 24 V loop supply with a constant-current limiter. KiCad 10, generated from Python. Rev G: routed, JLCPCB package included; not yet built.

Single-channel industrial 4-20mA current-loop reader, USB-C powered, built for ESPHome.

Rev G is the result of a second, independent design review (docs/DesignReview2026-09-20secondpass.md). Every circuit change below was simulated first; the decks are in sim/ and run on KiCad's own bundled ngspice.

State: 28 nets / 35 no-connects match the specification exactly, ERC 0 errors, schematic parity clean, placement DRC 4 (all deliberate silk-at-edge) + 5 library-internal, 52 parts + 4 holes + 3 fiducials, BOM 34 lines / 47 placements. Placed and routed - 0 unconnected, DRC unchanged at 4 + 5…

Main components on the ESP32 4-20mA Sensor

ESP32-S3-WROOM-1U-N4INA226AIDGSRAP2112K-3.3TRG1MT3608

ESP32 4-20mA Sensor bill of materials (BOM)

47 components, 35 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
ESP32-S3-WROOM-1U-N4
Espressif
U1
1
INA226AIDGSR
Texas Instruments
U3
1
AP2112K-3.3TRG1
AP2112K-3.3
Diodes Inc
U4
1
MT3608
Aerosemi
U5
1
BCP53-16
JSCJ
Q1
1
MMBT5401
JSCJ
Q2
1
AO3401A
Alpha & Omega
Q3
1
2N7002
JSCJ
Q4
1
TYPE-C 16PIN 2MD(073)
USB-C Receptacle
SHOU HAN
J1
1
KF250NH-5.0-3P
4-20mA Loop
Cixi Kefa
J2
1
KH-6X6X5H-STM
RESET
Kinghelm
SW1
1
KH-6X6X5H-STM
BOOT
Kinghelm
SW2
1
NCD0805R1
Power
Nationstar
LED1
1
USBLC6-2SC6
UMW
D1
1
SS34
MDD
D2
1
SMAJ28A
Jingdao Microelectronics
D3
1
1N4148W
ST (Semtech)
D4
1
SMAJ12A
MDD
D5
1
FNR4030S220MT
22uH
cjiang
L1
2
CL05A105KA5NQNC
1uF
Samsung Electro-Mechanics
C1, C6
Show 15 more
QtyPartRefs
1
CL21A226MAQNNNE
22uF
Samsung Electro-Mechanics
C2
4
CL05B104KO5NNNC
100nF
Samsung Electro-Mechanics
C3, C8, C9, C12
1
CL10A106KP8NNNC
10uF
Samsung Electro-Mechanics
C7
2
CS3225X7R106K500NRL
10uF/50V
Samwha
C10, C11
3
0402WGF1002TCE
10k
Uniroyal
R1, R11, R20
2
0402WGF4701TCE
4.7k
Uniroyal
R5, R6
2
0402WGF5101TCE
5.1k
Uniroyal
R7, R8
1
0402WGF3300TCE
330
Uniroyal
R9
2
FRC0402F3903TS
390k
FOJAN
R10, R21
1
FRC0805F3R32TS
3.32
FOJAN
R12
2
0402WGF100JTCE
10
Uniroyal
R13, R14
2
0402WGF1003TCE
100k
Uniroyal
R15, R22
1
RC0402FR-0718RL
18
Yageo
R16
1
0402WGF4702TCE
47k
Uniroyal
R17
1
0402WGF1001TCE
1k
Uniroyal
R18

ESP32 4-20mA Sensor design files

The KiCad project lives in the Diode663/ESP32_4-20mA_Sensor repository on GitHub; these links point at the commit this page was built from.

ESP32 4-20mA Sensor: common questions

What microcontroller does the ESP32 4-20mA Sensor use?

The ESP32 4-20mA Sensor is built around the ESP32-S3-WROOM-1U-N4, from the ESP32 family.

How big is the ESP32 4-20mA Sensor PCB?

The ESP32 4-20mA Sensor measures 40 × 61 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the ESP32 4-20mA Sensor?

47 components, from 35 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 ESP32 4-20mA Sensor design files?

From the Diode663/ESP32_4-20mA_Sensor 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 ESP32 4-20mA Sensor design in my own project?

Yes, under the terms of its CERN-OHL-P-2.0 license, which Diode663 chose for the repository.

Can I test firmware for the ESP32 4-20mA Sensor 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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