ES-12130 | 7Semi SCD41 High Accuracy CO₂, Temperature and Humidity Sensor Breakout I2CProduct Title

3D Model Viewer

Overview

The 7Semi SCD41 CO₂ Sensor Breakout is a compact, high-performance environmental sensing module designed for precise carbon dioxide monitoring in advanced applications. Built around Sensirion’s cutting-edge photoacoustic sensing technology, it delivers highly accurate and stable CO₂ measurements with minimal power consumption. In addition to CO₂ sensing, the module integrates temperature and humidity sensors, enabling real-time environmental compensation for improved measurement accuracy. With a digital I²C interface and factory calibration, the SCD41 breakout ensures seamless integration and immediate deployment in embedded systems, IoT devices, and industrial applications. Its ultra-low power operation and small footprint make it ideal for both portable and fixed installations, including smart air quality systems, HVAC automation, and environmental monitoring platforms.

Features

• Integrated temperature and humidity sensing for environmental compensation
• Wide CO₂ measurement range from 400 ppm to 40,000 ppm
• High accuracy: ±(50 ppm + 5% of reading)
• Ultra-low power operation suitable for battery-powered systems
• Digital I²C interface for easy integration
• Compact and lightweight design for embedded applications
• Factory calibrated and ready for immediate use
• Stable long-term performance

Technical Specification

Mechanical

Dimensions: L=30mm W=22mm H=7.83mm

Pinouts

I²C Wiring (Arduino UNO)

• VCC → 3.3V / 5V
• GND → GND
• SDA → A4
• SCL → A5

Arduino & ESP32 Notes

• Install the library via Arduino Library Manager

* Basic.ino
* Example for using the 7Semi SCD4x CO₂, temperature,
*          and humidity sensor with I²C on ESP32/Arduino.
*
* Features demonstrated:
* - Start/stop of standard periodic measurement
* - Reading CO₂ (ppm), temperature (°C), and humidity (%RH)
* - Notes on single-shot mode, offsets, and airflow considerations
*
* Sensor configuration used:
* - Periodic Mode : Standard (2 s polling)
* - I²C Frequency : 100 kHz (recommended for bring-up)
* - Supply Voltage: 3.3V–5.5V (module dependent)
* - Data Output   : CO₂ (ppm), Temperature (°C), RH (%)
*
* Connections:
* - SDA -> A4 Default board SDA (or define custom pin)
* - SCL -> A5 Default board SCL (or define custom pin)
* - VIN -> 3.3V / 5V (depending on module)
* - GND -> GND
*
* @author   7Semi
* @license  MIT
* @version  1.0
* @date     24 September 2025
***************************************************************/
 
#include <7Semi_SCD4x.h>
 
// I2C speed for bring-up (100 kHz recommended; raise later if stable)
#define I2C_FREQ_HZ 100000UL
 
// Set to -1 to use board defaults
#define I2C_SDA_PIN -1
#define I2C_SCL_PIN -1
 
// Polling period while in periodic modes
#define POLL_MS 2000UL
 
SCD4x_7Semi scd(&Wire);
 
uint32_t lastPoll = 0;
bool running = false;
bool lowPower = false;
 
void setup() {
  Serial.begin(115200);
  while (!Serial) {}
 
  Serial.println(F("\n== 7Semi SCD4x =="));
 
  while (!scd.begin(I2C_SDA_PIN, I2C_SCL_PIN, I2C_FREQ_HZ)) {
    Serial.println(F("SCD4x not detected. Check wiring/power."));
    delay(1000);
  }
 
  // Start in standard periodic mode by default
  if (scd.startPeriodicMeasurement()) {
    running = true;
    lowPower = false;
    Serial.println(F("Started standard periodic mode. First valid reading ~5s."));
  } else {
    Serial.println(F("failed to start periodic mode."));
  }
}
 
/**
- Poll data-ready every 2 s
- When ready, read CO₂ (ppm), temperature (°C), humidity (%RH)
- Prints values to Serial (with basic formatting)
*/
void loop() {
  static uint32_t lastCheck = 0;
  if (millis() - lastCheck < 2000) return;  // every 2 s
  lastCheck = millis();
 
  uint16_t ready = 0;
  // Bit 10..0 used as "new data available" in many Sensirion examples
  if (scd.getDataReadyStatus(ready) && (ready & 0x07FF)) {
    uint16_t co2;
    float temp, rh;
 
    if (scd.readMeasurement(co2, temp, rh)) {
      Serial.print("CO₂: ");
      Serial.print(co2);
      Serial.print(" ppm\t");
 
      Serial.print("Temp: ");
      Serial.print(temp, 2);
      Serial.print(" °C\t");
 
      Serial.print("RH: ");
      Serial.print(rh, 1);
      Serial.println(" %");
    } else {
      Serial.println("Read failed (CRC/I2C error)");
    }
  }
}
 
/* ===================== Notes =====================
- If you never see data ready:
   * Re-check wiring, pull-ups, and I²C pins for your board.
   * Try 100 kHz I²C during bring-up.
   * Ensure stable power; SCD4x can run from 3.3–5.5 V depending on module.
 
- If values look offset:
   * Consider setTemperatureOffset() to compensate board self-heating.
   * Avoid strong airflow directly on the sensor.
 
- If you need single-shot mode:
   * Use measureSingleShot()/measureSingleShotRhtOnly() and then readMeasurement().
=================================================== */

7Semi SCD4x Working Demonstration

Downloads

Frequently Asked Questions