C8 NDIR CO2 Sensor Module – 400–5000ppm, UART/PWM, 1ppm Resolution

The C8 CO2 sensor module is a compact, general-purpose carbon dioxide sensor module that uses non-dispersive infrared (NDIR) absorption technology to measure CO2 concentration in the air. Unlike metal-oxide (MOX) gas sensors that respond to a broad range of combustible gases and suffer from baseline drift, the NDIR principle provides good selectivity for CO2, minimal dependence on oxygen concentration, and a long operational life. The module is built around a precise optical path and sophisticated circuit design, and it includes built-in temperature compensation to maintain accuracy across changing ambient conditions.

The sensor covers a measurement range of 400 to 5000 ppm with a resolution of 1 ppm and an accuracy of ±(50ppm + 3% of reading). It provides two independent output interfaces: a UART serial interface for direct connection to microcontrollers and a PWM output whose duty cycle corresponds to the measured CO2 concentration. This dual-output design makes the module compatible with a wide range of host platforms, including Arduino, ESP32, Raspberry Pi, and industrial controllers, without requiring external signal conditioning. The data update interval is less than 3 seconds (typically 1 second), allowing the sensor to track changing CO2 levels in real time.

The module is housed in a small ABS enclosure measuring 33 × 21 × 11 mm and is finished in silver. It operates over a temperature range of -10°C to +60°C (per the Aftab Rayaneh listing) and a humidity range of 0–95% RH. The module requires a 5V DC supply (the C8 family is specified for 4.5–5.5V) and draws a peak current of approximately 150mA, with an average of about 70mA. Its compact size, low cost, and dual digital outputs make it suitable for indoor air quality monitors, HVAC equipment, fresh-air systems, air purifiers, smart home devices, and educational projects. The module is a complete sensor assembly—it does not include a display, data logger, or enclosure beyond the ABS housing.