2 layers19 × 19 mm
2 layers73.3 × 73.3 mm
Modbus room sensor
njh/modbus-room-sensorOpen Source Modbus Room Sensor
- Size
- 73.3 × 73.3 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 41
- Nets
- 38
- Pads
- 135
- Tracks, vias
- 215, 46
- Pours
- 6
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 11 Jun 2025
- Updated
- 7 Nov 2026
Overview
Modbus room sensor is an open-source printed circuit board by njh, from the njh/modbus-room-sensor repository on GitHub, published under the MIT licence. It is a 2-layer board of 73.3 × 73.3 mm with 41 parts on 38 nets, routed with 215 tracks and 46 vias.
It is built around the ATMEGA328P-AU, THVD2410DRB and AP63203WU, with the SMAJ24CA and SS210 among its other parts. Its parts include 13 capacitors, 6 resistors, 6 connectors, 3 ICs and 3 diodes. It belongs with the sensors and measurement boards and the AVR (ATmega, ATtiny) boards of this library.
Main components
5
ATMEGA328P-AU
TQFP-32(7x7)-40℃~+85℃ 1.8V~5.5V 10bit 1KB 20MHz 23 2KB 32KB 8 Bit AVR Built-in FLASH TQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
THVD2410DRB
SON-8(3x3)-40℃~+125℃ 1 1 256 3V~5.5V 500Kbps Half-Duplex Transceiver ±16kV SON-8(3x3) RS-485 / RS-422 ICs ROHSTexas InstrumentsRS-485 / RS-422 ICs
AP63203WU
TSOT-23-6-40℃~+85℃@(TA) 1 1.1MHz 22uA 2A 3.3V 3.8V~32V Buck Built-in Fixed Overcurrent Protection、Light load efficient mode、Cycle-by-cycle current limiting、Hiccup current limiting、EMI optimization (spread spectrum) Step-down type Yes TSOT-23-6 DC-DC Converters ROHSDiodes IncorporatedDC-DC Converters
SMAJ24CA
DO-214AC(SMA)-55℃~+150℃ 10.3A 24V 26.7V 38.9V 400W 5uA Bidirectional TVS DO-214AC(SMA) ESD and Surge Protection (TVS/ESD) ROHSGOODWORKESD And Surge Protection (TVS/ESD)SS210
SMA(DO-214AC)-55℃~+150℃ 1 Independent 100V 2A 500uA@100V 850mV@2A SMA(DO-214AC) Schottky Diodes ROHSMDDSchottky Diodes
README
README.mdModbus Temperature and Humidity Sensor
An open source and open hardware Modbus Temperature and Humidity Sensor.
License
This project is licensed under the terms of the MIT license. See the file LICENSE for details.
Parts
41| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 0.1uF | Capacitor_SMD:C_0402_1005Metric | C10, C11, C12, C13, C14 |
| 4 | 10K | Resistor_SMD:R_0603_1608Metric | R1, R4, R5, R6 |
| 4 | MountingHole | MountingHole:MountingHole_2.7mm_M2.5 | H1, H2, H3, H4 |
| 2 | 0.1uF | Capacitor_SMD:C_0603_1608Metric | C3, C4 |
| 2 | 22pF | Capacitor_SMD:C_0603_1608Metric | C7, C8 |
| 2 | 22uF | Capacitor_SMD:C_1206_3216Metric | C5, C6 |
| 1 | 0.5A | Capacitor_THT:C_Disc_D8.0mm_W5.0mm_P5.00mm | F1 |
| 1 | 10uF | Capacitor_SMD:C_0805_2012Metric | C2 |
| 1 | 120R | Resistor_SMD:R_1206_3216Metric | R3 |
| 1 | 1K | Resistor_SMD:R_0603_1608Metric | R2 |
| 1 | 4.7uH | Inductor_SMD:L_Sunlord_SWPA4030S | L1 |
| 1 | 47uF | Capacitor_THT:CP_Radial_D6.3mm_P2.50mm | C1 |
| 1 | 8MHz | Crystal:Crystal_SMD_5032-2Pin_5.0x3.2mm | Y1 |
| 1 | AP63203WU | Package_TO_SOT_SMD:TSOT-23-6 | U5 |
| 1 | ATmega328P-A | Package_QFP:TQFP-32_7x7mm_P0.8mm | U1 |
| 1 | FTDI Serial | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J2 |
| 1 | I2C | Connector_JST:JST_PH_B4B-PH-K_1x04_P2.00mm_Vertical | J5 |
| 1 | ICSP | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J3 |
| 1 | Red LED | LED_SMD:LED_0805_2012Metric | D3 |
| 1 | SMAJ24CA | Diode_SMD:D_SMA | D1 |
| 1 | SS210 | Diode_SMD:D_SMA | D2 |
| 1 | Screw Terminal | Kefa HT396:Kefa_HT396R-3.96-04P_1x04_P3.96mm_Horizontal | J1 |
| 1 | Sensor Board | Connector_PinSocket_2.54mm:PinSocket_1x05_P2.54mm_Horizontal | J4 |
| 1 | THVD2410DR | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U3 |
| 1 | Terminate | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | JP1 |
| 1 | Unit ID | Connector_PinHeader_2.54mm:PinHeader_2x04_P2.54mm_Vertical | J6 |
The 39 most common of 41 parts.
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Questions
How big is the Modbus room sensor PCB?
It measures 73.3 × 73.3 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Modbus room sensor use?
41 parts, built around the ATMEGA328P-AU, THVD2410DRB, AP63203WU and SMAJ24CA. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Modbus room sensor KiCad files?
From the njh/modbus-room-sensor repository on GitHub, at the commit this page was made from: the board is modbus-room-sensor.kicad_pcb and its schematic modbus-room-sensor.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Modbus room sensor design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).