We are excited to share this month's fourth sensor :)
It took a long time to organize all our parts, but perhaps it's time to put their magic to use. Let's add some exciting new sensor options to HA! We completed three sensors this month: BLEDongle-1M (BP gateway), PM25-1 (dust particle sensor), and SFA-1 (formaldehyde sensor).Now we think it’s the perfect time to add another new member. We’ve enhanced our previous SCO2-1 based on our experience manufacturing hundreds of SCO2-1 units. We hope to meet the needs of users with higher requirements. We’ve constructed a new enhanced CO2 sensor using the SCD41 sensor, which improves detection range and accuracy. In fact, we believe that the SCO2-1 is sufficient for many users, but some users desire a wider detection range. We have tested this solution and would like to share it with you.
In typical applications, we believe that SCO2-1 (SCD40) is sufficient for most needs. However, as a more advanced product, SCD41 offers several enhancements over SCD40, including:
- The measurement range has been expanded from 0–2000 ppm to 0–5000 ppm.
- The accuracy has been optimized from ±(50 ppm + 5% of the reading) for 400–2000 ppm to a segmented accuracy: 400–1000 ppm is ±(50 ppm + 2.5%),±(50 ppm + 3%) for 1001–2000 ppm, and ±(40 ppm + 5%) for 2001–5000 ppm.
- Additionally, there are power-saving optimizations, including support for low-power cycle measurement and single-shot mode (Single Shot). However, since we do not use battery mode, this feature can be ignored.
- Furthermore, the SCD41 has been certified to meet multiple indoor air quality (IAQ) standards, including EN50543, RESET, and California Title 24.
Based on our familiar C3 architecture and the stable circuit design on the SCO2-1, we have redesigned a simplified housing, placing the SCD41 inside the housing and designing ventilation holes on the top.
As before, due to the heat generated by the ESP32, there may be slight temperature interference, but in our tests, this does not appear to have a significant impact on the measurement results.
In summary, this is just the beginning. We welcome you to join us on this adventure.
We are currently inviting the first batch of adventurers to join us. As usual, we are offering a 20% discount.
In terms of the sensor housing design, we have created a closed structure that houses the sensor inside the housing and uses a mesh to accept carbon dioxide-containing air.
In terms of firmware, we have made the following improvements:
- Added user-friendly displays showing the current carbon dioxide level and recommendations.
- Introduced a secondary breathing index, which represents the probability of inhaling carbon dioxide exhaled by others.
- Optimized the firmware update interval from 10 seconds to a maximum of 5 seconds, which is the limit for the SCD41 sensor. Of course, users who do not require such high performance can adjust this setting accordingly.
- Using the ESPHome 2025.6.3 kernel.
- Modified the SCD4x driver to include the SCD41 serial number information and the hardware type read by the kernel (as it is difficult to distinguish between SCD40 and SCD41 based on appearance alone).
- Added the automatic calibration switch, which was frequently requested by users. Further testing may be needed to confirm its effectiveness. It is called [SCD41 ASC Mode], disabled by default, and you need to enable it manually in HA.
- Added an ambient pressure setting service
set_ambient_pressure, which can be used to automatically input the ambient pressure values from other devices to the SCD41 for calibration.
In summary, we think this experiment might be interesting, and we welcome everyone to join us!
