Electrochemical Gas Sensors – Hardware details
Pinout
Click here for a high-resolution image of the pinout.
Pin details
| Pin Marking | Pin Name | Description |
|---|---|---|
| GND | Ground | Common ground for power and signals. |
| VCC | Power | Supply voltage (both 5V and 3V3 are supported). |
| SDA | Data | I2C data line for communication. |
| SCL | Clock | I2C clock line for communication. |
| AIN1 | Analog input | Analog input 1 |
| AIN2 | Analog input | Analog input 2 |
| AIN3 | Analog input | Analog input 3 |
| VOUT | Analog output | Analog output from LMP |
| ALERT | Digital output | High when the conversion data exceeds the Hi_thresh register or falls below the Lo_thresh register value. |
| LMPEN | LMP enable | Module Enable, Active-Low |
Qwiic (formerly easyC)
Qwiic (formerly easyC) details and specifications
Learn about hardware specifications, compatibility, and usage of the Qwiic connector.
Dimensions
- Board Dimensions: 38 × 38 mm (1.5 × 1.5 inch)
- Header Pin Holes: 1.5 mm
- Screw Holes: Designed for M3 screws (3.2 mm diameter)
- Soldered boards are LEGO compatible! 🧱
LMPEN pin functionality
The LMP91000 comes with a unique and fixed I2C address of 0x48. It is still possible to connect more than one LMP91000 to an I2C bus and select each device using the LMPEN pin. The LMPEN simply enables or disables the I2C communication of the LMP91000. When the LMPEN is at a logic level low, all I2C communication is enabled; conversely, when the LMPEN is at a high logic level, I2C communication is disabled. In a system based on a microcontroller with more than one LMP91000 connected to the I2C bus, the I2C lines (SDA and SCL) are shared, while the LMPEN of each LMP91000 is connected to a dedicated GPIO port of the microcontroller. The microcontroller starts communication by asserting one out of N LMPEN signals, where N is the total number of LMP91000s connected to the I2C bus. Only the enabled device will acknowledge the I2C commands. After finishing communication with this particular LMP91000, the microcontroller de-asserts the corresponding LMPEN and repeats the procedure for the other LMP91000s.
Sensor datasheets
| SKU | Sensor name | Datasheet |
|---|---|---|
| 333325 | SGX-4SO2 - Sulphur Dioxide sensor | Datasheet |
| 333326 | SGX-4NO2 - Nitrogen Dioxide sensor | Datasheet |
| 333327 | SGX-4NO-250 - Nitric Oxide sensor | Datasheet |
| 333328 | SGX-4CO - Carbon Monoxide sensor | Datasheet |
| 333329 | SGX-403-20 - Ozone sensor | Datasheet |
| 333330 | SGX-4NH3-300 - Ammonia sensor | Datasheet |
| 333331 | SGX-4H2S-100 - Hydrogen Sulphide sensor | Datasheet |
| 333332 | SGX-4CL2 - Chlorine sensor | Datasheet |
Jumper Details
This board contains hardware jumpers. See below for their locations and functions:
| Jumper | Default State | Function |
|---|---|---|
| JP1 | NC (Normally closed) | Connects SDA/SCL pull-up resistors to 5V for I2C communication. |
| JP2 | NC (Normally closed) | Connects SDA/SCL pull-up resistors to 3.3V for I2C communication. |
| JP3 | NC (Normally closed) | When connected, the voltage regulator is powered by 5V, stepping it down to 3.3V for the IC. |
| JP4 | NO (Normally open) | When shorted, it bypasses the voltage regulator, allowing the board to be powered directly from 3.3V via headers. Ensure JP3 is disconnected if JP4 is connected. |
| JP5 | NC (Normally closed) | When shorted, it sets the I2C address to 0x49. |
| JP6 | NO (Normally open) | When shorted, it sets the I2C address to 0x4A. |
| JP7 | NO (Normally open) | When shorted, it sets the I2C address to 0x4B. |
Hardware repository
The hardware repository contains everything you need to understand, modify, or manufacture the board. The different output folders are versioned. You can check which board version you have specifically by finding the version mark on the PCB.
Below is an overview of the available files.
CAD files
We use KiCad, an open-source PCB design tool. You can open and edit the .kicad_pro project file, which includes both the schematic and PCB layout.
The PANEL files are used internally for production.
Schematic
The OUTPUTS folder contains the schematic in .pdf format, exported from KiCad.
BOM (Bill of Materials)
The bill of materials (BOM) is provided in two formats:
- A standard
.csvtable, listing all components, part numbers, and values. - An interactive BOM (
.html) that visually highlights each component on the PCB, making it easy to locate and reference parts.
3D files
A 3D model of the PCB is available in .step format, allowing you to inspect the board design in CAD software.
Gerber files
Gerber files are essential for PCB manufacturing, as they contain precise instructions for each layer of the board. The repository includes standard Gerber outputs in a .zip file, such as:
- Copper layers (
.Cu.gbr) – Defines the traces and pads on the board. - Solder mask layers (
.Mask.gbr) – Specifies the protective solder mask. - Silkscreen layers (
.Silkscreen.gbr) – Contains text and component markings. - Paste layers (
.Paste.gbr) – Used for stencil fabrication in SMD assembly. - Drill files (
.drl) – Provides drilling coordinates for vias and holes. - Board outline (
.Edge_Cuts.gbr) – Defines the shape of the PCB. - Gerber job file (
.gbrjob) – Describes the set of Gerber files used for production.
These files are ready for fabrication and can be used in PCB manufacturing.
Compliance
The Compliance section includes important regulatory and safety documentation for this product. These files ensure compliance with relevant industry standards and legal requirements.
- CE – Certification document confirming compliance with EU safety, health, and environmental requirements.
- UKCA – UKCA (UK Conformity Assessed) certification for the UK market.
- Safety Instructions – Safety guidelines and precautions in both English and German.
- Info.txt – Contains product details such as SKU, country of origin, HS tariff code, and barcode.