> **Source:** Core Electronics is an Australian maker-electronics retailer and manufacturer based in Newcastle, NSW, run by a team of makers and educators. We design and manufacture our own product lines (PiicoDev, CE originals) and are official retailers for iconic maker and industrial brands including Raspberry Pi, Arduino, Adafruit, SparkFun and DFRobot. Orders ship Australia-wide from our Newcastle warehouse. Prices are in AUD and include GST. Pricing, stock and dispatch on this page are generated from the store's live catalog. Full machine-readable index: https://core-electronics.com.au/llms.txt # SparkFun CO2 Sensor - STC31 (Qwiic) **Type:** Product page · **SKU:** SEN-29260 · **Brand:** [Sparkfun](https://core-electronics.com.au/brands/sparkfun-australia) **Page:** https://core-electronics.com.au/sparkfun-qwiic-stc31-high-range-co2-sensor.html ([markdown](https://core-electronics.com.au/sparkfun-qwiic-stc31-high-range-co2-sensor.html.md)) Need to measure high concentrations of carbon dioxide? When standard CO2 sensors won't cut it, the SparkFun Qwiic STC31 Sensor is your solution. This... ## Pricing - **Price:** $224.95 (inc GST) — $204.50 AUD, exc GST ## Availability & dispatch - Out of stock — the product page offers email notification when it returns. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=SEN-29260:1` (comma-separated SKU:qty pairs) and share the link. Opening it shows a confirmation page with live pricing and stock before anything is added to the cart. - **Verify the cart first:** fetch `https://core-electronics.com.au/cart/link/SEN-29260:1.md` for live line prices (inc & exc GST, quantity discounts applied), stock and dispatch estimates, and totals. Append `/to/{AU-postcode}` (or `/to/{country-code}:{postcode}`) before `.md` for delivery options and prices to that destination. Unknown, retired, or out-of-stock SKUs are flagged. (Query form `cart/link.md?items=...` also works but some robots parsers refuse query strings here.) - **Checkout** is completed on-site and includes a captcha at the payment step. Share the cart link; checkout takes it from there. - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## Description Need to measure high concentrations of carbon dioxide? When standard CO2 sensors won't cut it, the SparkFun Qwiic STC31 Sensor is your solution. This powerful sensor from Sensirion is designed to measure CO2 concentrations all the way up to a staggering 100% volume! The STC31 is built for applications where reliability is key. It uses a revolutionary thermal conductivity measurement principle, combined with Sensirion's patented CMOSens® technology, to deliver superior repeatability and long-term stability. This means the sensor element, signal processing, and digital calibration are all integrated onto a single tiny chip. ### Expected CO2 Accuracy Ranges - Two CO2 Measurement Ranges: 0 to 25 vol% and 0 to 100 vol% - Measurement Repeatability: 0.2 vol% - Accuracy (0-25% range): 0.5 vol% + 3% of measured value - Accuracy (0-100% range): 1 vol% + 3% of measured value For best-in-class performance, we've integrated a separate SHTC3 humidity and temperature sensor right on the board. This allows the STC31 to provide fully compensated CO2 measurements that also account for atmospheric pressure — a crucial feature for reliable data, which is handy if, like us, you’re up in the mountains! ### Plug-and-Play with Qwiic As part of the SparkFun Qwiic Connect System, this board is incredibly easy to use. Simply plug it into your development board with a Qwiic cable and you're ready to go—no soldering required! For advanced users, the STC31’s I2C address can be configured using the split-pad jumpers on the back of the board. The SHTC3’s I2C address is non-configurable; you will need a [Qwiic Mux](https://core-electronics.com.au/search/?q=16784) if you want to connect multiple sensors to the same bus. Our [Arduino library](https://github.com/sparkfun/SparkFun_STC3x_Arduino_Library) contains example sketches for the Arduino IDE to get you up and running quickly. It can be downloaded through the Arduino Library manager: search for 'SparkFun STC3x', or it can be found in the Documents tab above. ### Features & Specs - Sensirion STC31 CO2 Sensor - Thermal conductivity sensor provides calibrated gas concentration and temperature output - Calibrated for: CO2 in N2; and CO2 in air - Measurement ranges: 0 to 25 vol%; 0 to 100 vol% - Accuracy: 0.5 vol% + 3% measured value; 1 vol% + 3% measured value - Repeatability: 0.2 vol% - Temperature measurement range: -20 °C to +85 °C - Concentration and temperature resolution: 16-bit - Start-up time: 14 ms - I2C address (configurable): 0x29 (default), 0x2A, 0x2B, 0x2C - Supply Voltage: 2.7VMin, 3.3VTyp, 5.5VMax - **Note:** Qwiic bus operates at 3.3VMax - Sensirion SHTC3 Humidity and Temperature Sensor - Allows the STC31 to compensate for humidity and temperature - Typical accuracy: ±2 %RH and ±0.2 °C - Specified humidity range (extended): 0 to 100 %RH - Specified temperature range: -40 °C to +125 °C - I2C address (non-configurable): 0x70 - Supply Voltage: 1.62VMin, 3.3VTyp, 3.6VMax - **Note:** Qwiic bus operates at 3.3VMax - Dual Qwiic connectors - Power LED (configurable) - I2C pull-ups (configurable) ### Documentation - [Schematic](https://cdn.sparkfun.com/assets/c/9/5/0/b/SparkFun_STC31.pdf) - [KiCad Files](https://cdn.sparkfun.com/assets/e/a/f/8/d/SparkFun_STC31.zip) - [Hookup Guide](https://docs.sparkfun.com/SparkFun_CO2_Sensor-STC31) - Datasheets: - [STC31](https://core-electronics.com.au/attachments/localcontent/Sensirion_Thermal_Conductivity_Datasheet_STC31_D1_91863ae151c.pdf) - [SHTC3](https://cdn.sparkfun.com/assets/9/4/d/1/3/Sensirion_Humidity_Sensors_SHTC3_Datasheet.pdf) - [STC Field Calibration Guide](https://core-electronics.com.au/attachments/localcontent/Sensirion_TC_AN_STCxx_FieldCalibration_D1_33638bd68c7.pdf) - [STC Design-In Guide](https://core-electronics.com.au/attachments/localcontent/Sensirion_TC_AN_STCxx_Design-In_Guide_D1_32078fdac6d.pdf) - Libraries: - [Arduino Library](https://github.com/sparkfun/SparkFun_STC3x_Arduino_Library) - [Python / MicroPython / CircuitPython Package](https://github.com/sparkfun/qwiic_stc3x_py) - [GitHub Hardware Repo](https://github.com/sparkfun/SparkFun_CO2_Sensor-STC31) **WARNING:** This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. See link below for more information. [www.P65Warnings.ca.gov](https://www.P65Warnings.ca.gov) ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/S/E/SEN-29260-1.jpg)