From the creation time of the engineering schematic diagram, it can be seen that this is a project that has been planned for a long time. The exam is approaching, and the failure of the first version has made the open source even worse:)

Note: This project requires Tuya Smart Zigbee Gateway

OEM clone link: Since the firmware has been deactivated, friends who have not created a plan are temporarily unable to purchase the module. If the firmware is re-released later, the link will be updated here.

G:

1. This project uses the CO2 alarm made by Tuya Zigbee (ZTU) module, which can not only detect the current air CO2 content, but also detect the temperature and humidity to form a linkage. It still requires no development and no need to write code;

2. This temperature and humidity meter has high-precision temperature and humidity detection functions, CO2 setting range and linkage alarm functions, and the trigger concentration is variable;

3. This module consumes low power and can be powered by battery through the reserved connection port or by installing a 220VAC DC module;

4. Built-in a high-precision SHT40 sensor, which can realize the function of temperature and humidity sensor, three uses in one machine.

principle:

1. This project uses serial communication between the MH-Z19C carbon dioxide sensor and the Tuya module (ZTU), which can detect the concentration of 400~5000PPM and has a service life of >5 years;

2.MH-Z19C carbon dioxide gas sensor is a general intelligent small sensor. The non-dispersive infrared (NDIR) principle is used to detect CO2 existing in the air. It has good selectivity, no oxygen dependence, long life, and has serial port output and PWM. This project only uses the serial port output.

Of course, the price is also, emmm...

APP operation interface:

PCB display: