2 layers50 × 25 mm Sensor module, the printed circuit board in 3D

Sensor module

Based on the Atlas Scientific EZO kit and a Huba 713

Size: 50 × 25 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 45
Nets: 27
Pads: 138
Tracks, vias: 327, 67
Pours: 2
Routed: Yes
KiCad: KiCad 8.0 (file 20240108)
Created: 19 Feb 2024
Updated: 15 Jul 2026

Overview

Sensor module is an open-source printed circuit board by Pollex, from the Pollex/MFM-Module-EC-Pressure repository on GitHub. It is a 2-layer board of 50 × 25 mm with 45 parts on 27 nets, routed with 327 tracks and 67 vias.

It is built around the ATTINY1614-SSN, DS18B20 and AP2205-50W5-7-MS, with the SN74LVC1T45DCK among its other parts. Its parts include 16 capacitors, 10 connectors, 9 resistors, 4 ICs and 4 diodes. It belongs with the sensors and measurement boards and the AVR (ATmega, ATtiny) boards of this library.

Main components

README

readme.md

TODOs

Open Q's

Calibration must happens when probe is switched. When and how to do this?
Is it worth disabling the EZO circuit LED?
- Perhaps sending the command takes more power than the LED being on

Atlas Scientific EZO Circuit

Send probe K value from EEPROM in perform_measurement
Send calibration string from EEPROM in perform_measurement
Send water temperature from EEPROM in perform_measurement

Parts

Qty	Value	Footprint	References
7	100nF	Capacitor_SMD:C_0603_1608Metric	C1, C5, C6, C9, C10, C12, C13
4	0R	Capacitor_SMD:C_0603_1608Metric	R6, R8, R10, R11
4	NM	Capacitor_SMD:C_0603_1608Metric	C7, C11, R3, R7
4	WE 824022	Package_TO_SOT_SMD:SOT-23-3L	D1, D2, D3, D4
3	1uF	Capacitor_SMD:C_0805_2012Metric	C2, C3, C8
3	4k7	Capacitor_SMD:C_0603_1608Metric	R1, R2, R5
2	10k	Capacitor_SMD:C_0603_1608Metric	R4, R9
1	2.2uF	Capacitor_SMD:C_0805_2012Metric	C4
1	4.7nF	Capacitor_SMD:C_0603_1608Metric	C14
1	AP2205-50W5-7	Package_TO_SOT_SMD:SOT-23-5	U2
1	ATtiny1614-SS	Package_SO:SOIC-14_3.9x8.7mm_P1.27mm	U1
1	Atlas Schientific ConductivityKit isolator	TerminalBlock_Phoenix:TerminalBlock_Phoenix_MPT-0,5-5-2.54_1x05_P2.54mm_Horizontal	J1
1	Conductivity	Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Vertical	J4
1	DS18B20	TerminalBlock_Phoenix:TerminalBlock_Phoenix_MPT-0,5-3-2.54_1x03_P2.54mm_Horizontal	J2
1	Debug UART	Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical	J10
1	Huba Pressure	Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical	J6
1	Huba Pressure sensor	TerminalBlock_Phoenix:TerminalBlock_Phoenix_MPT-0,5-3-2.54_1x03_P2.54mm_Horizontal	J3
1	LOGO	Logos:logo-pollex-15mm	G***
1	MFM Module - Left	Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical	J7
1	MFM Module - Right	Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical	J8
1	PTS636 SM43 SMTR LFS	Button_Switch_SMD:SW_Tactile_SPST_NO_Straight_CK_PTS636Sx25SMTRLFS	SW1
1	SN74LVC1T45DCK	Package_TO_SOT_SMD:SOT-363_SC-70-6	U4
1	SiP32432DR3	Package_TO_SOT_SMD:SOT-363_SC-70-6	U3
1	Temperature	Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical	J5
1	UPDI Interface	Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical	J9

Questions

How big is the Sensor module PCB?

It measures 50 × 25 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Sensor module use?

45 parts, built around the ATTINY1614-SSN, DS18B20, AP2205-50W5-7-MS and SN74LVC1T45DCK. 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 Sensor module KiCad files?

From the Pollex/MFM-Module-EC-Pressure repository on GitHub, at the commit this page was made from: the board is hardware/sensor-module.kicad_pcb and its schematic hardware/sensor-module.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Sensor module design in my own project?

Its repository states no licence, so its author keeps all rights: ask Pollex before reusing the design.

Category and platform

Sensors and measurement AVR (ATmega, ATtiny)

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/pollex-mfm-module-ec-pressure" title="Sensor module in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe>

A picture

<img src="https://pcbkit.io/embed/boards/pollex-mfm-module-ec-pressure.jpg" alt="Sensor module" width="1200" height="900">

A picture that opens the board, for a README

[![Sensor module](https://pcbkit.io/embed/boards/pollex-mfm-module-ec-pressure.jpg?size=s)](https://pcbkit.io/boards/pollex-mfm-module-ec-pressure)

Source

Repository: Pollex/MFM-Module-EC-Pressure
Board file: hardware/sensor-module.kicad_pcb
Commit: e2a83b4
Licence: Not stated

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