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OTthing

Phunkafizer·OT-Thing·PCB/OTThing.kicad_pcb

OTthing PCB layout, top view — open source ESP32 board by Phunkafizer

About the OTthing PCB

OTthing is an open source ESP32 PCB design by Phunkafizer, published on GitHub under the GPL-3.0 license. It is a 2-layer board measuring 51 × 71 mm, with 93 components from 45 distinct parts.

Its main chip is the ESP32-C3-WROOM-02, from the ESP32 family. Other key parts include the TPS61041, USBLC6-2SC6 and AMS1117-3.3. By type, the board carries 38 resistors, 18 diodes, 12 transistors, 10 capacitors, 6 inductors and 4 ICs.

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

From the project

A compact universal OpenTherm WiFi Interface

A compact WiFi OpenTherm (master & slave) interface

https://www.seegel-systeme.de/2025/01/05/ot-thing-das-universelle-wifi-opentherm-interface/

OTthing is a versatile OpenTherm gateway that connects your heating system to the Internet via WiFi. It acts as an OpenTherm master (controlling your boiler) and/or slave (integrating with room thermostats), providing real-time monitoring and control through a modern web interface and Home Assistant integration.

OTthing, from the project README
From the project README

Main components on the OTthing

TPS61041ESP32-C3-WROOM-02USBLC6-2SC6AMS1117-3.3

OTthing bill of materials (BOM)

93 components, 45 distinct parts.

QtyPartRefs
1
TPS61041
IC1
1
ESP32-C3-WROOM-02
U1
1
USBLC6-2SC6
U5
1
AMS1117-3.3
U6
6
BC857C
Q1, Q4, Q5, Q6, Q7, Q11
6
BC847C
Q2, Q8, Q9, Q10, Q12, Q13
1
USB_C_Receptacle_USB2.0
J3
1
~
J4
1
G6K-2F-Y-5V
K1
1
RST/CONFIG
SW1
1
BOOT
SW2
1
ZMM4V3
D1
1
ZMM15
D2
2
PTVS3V3S1UR,115
D3, D17
6
LL4148
D4, D5, D6, D7, D8, D18
1
MBR0540
D9
1
RD
D10
2
GN
D11, D13
2
YL
D12, D14
1
PESD24VL1BA
D15
Show 25 more
QtyPartRefs
1
PTVS24VS1UR
D16
5
~
FB1, FB2, FB3, FB4, FB5
1
10µ
L1
2
470pF
C1, C3
3
10µ
C2, C4, C5
1
100µ
C6
2
4µ7
C7, C9
1
22pF
C8
1
470µ
C10
9
4k7
R1, R4, R29, R30, R31, R36, R38, R39 +1
5
120
R2, R6, R10, R11, R24
1
18k
R3
1
470
R5
3
330
R7, R22, R33
2
5k1
R8, R9
3
3k3
R12, R14, R23
3
33k
R13, R21, R27
4
12k
R15, R25, R26, R28
1
220k
R16
1
6k8
R17
1
22k
R18
1
39
R19
1
100
R20
1
1k
R32
1
10k
R37

OTthing design files

The KiCad project lives in the Phunkafizer/OT-Thing repository on GitHub; these links point at the commit this page was built from.

OTthing: common questions

What microcontroller does the OTthing use?

The OTthing is built around the ESP32-C3-WROOM-02, from the ESP32 family.

How big is the OTthing PCB?

The OTthing measures 51 × 71 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the OTthing?

93 components, from 45 distinct parts. The full bill of materials is listed on this page.

Where can I download the OTthing design files?

From the Phunkafizer/OT-Thing repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the OTthing design in my own project?

Yes, under the terms of its GPL-3.0 license, which Phunkafizer chose for the repository.

Can I test firmware for the OTthing 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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