설명
The MH-Z19C carbon dioxide gas sensor (hereinafter referred to as the sensor) is a general-purpose intelligent small sensor that uses the principle of non-dispersive infrared (NDIR) to detect the presence of C02 in the air. And other features; built-in temperature compensation: simultaneously has serial output, PWM output, easy to use. The sensor is a high-performance sensor made by closely combining mature infrared absorption gas detection technology with sophisticated optical circuit design and sophisticated circuit design.
Product parameters:
Detection gas: carbon dioxide
Power supply voltage: DC (5.0 ± 0.1) V
Average current: <40mA (@5V power supply)
Peak current: 125 to (@5V power supply)
Interface level: 3. 3v (compatible with 5v)
Measuring range: 400-5000PPM optional
Output signal: serial UART (TL level 3.3V)
Warm-up time: 1min
Response time: T90< 120s
Working temperature: -10-50degree
Working humidity: 0~95%RH (no condensation)
Pin description:
Vin: Power +(in)
GND: power supply-(GND)
PWM: PWM
Hd: HD (zero calibration, low level is effective for more than 7 seconds)
Rx: UART (RXD) TTL level data input
Tx: UART (TXD) TTL level data output
Output method:
PWM output
Assume the measurement range is 400-2000ppm
CO2: Concentration output range: 400-2000ppm
Period: 1004ms±5%
High level output at the beginning of the cycle: 2ms (theoretical value)
Central period: 1000ms±5%
Low level output at the end of the period: 2ms (theoretical value)
Calculation formula for obtaining current CO2 concentration value by PWM: Cppm=2000X (TH-2ms)/(TH+TL-4ms)
Cppm: CO2 concentration value calculated by the unit of ppm
TH: the time when the output is high level in one output cycle
TL: the time when the output is low in one output cycle
Serial output (UART)
Hardware connection, connect the sensor’s Vin-GND-RXD-TXD to the user’s 5V-GND-TXD-RXD. (User terminal must use TTL level)
Precautions:
- In the process of welding, installation and use of the sensor, the gold-plated plastic cavity should be prevented from withstanding pressure in any direction.
- If the sensor needs to be placed in a small space, this space should be well ventilated, especially the two diffusion windows should be in a well ventilated position.
- The sensor should be far away from the heat source, and avoid direct sunlight or other heat radiation.
- The sensor should be calibrated regularly, and the calibration period is recommended to be no more than 6 months.
- Do not use the sensor for a long time in the environment with high dust density.
- In order to ensure that the sensor can work normally, the power supply voltage must be maintained at (5.0 ± 0.1) VDC. The power supply current must not be less than 150mA
- If it is not within this range, the sensor may be faulty, the output concentration of the sensor is low or the sensor cannot work normally.
- When manually calibrating the zero point or sending the command to calibrate the main points, it must be stable
- Work continuously for more than 20 minutes in a gas environment (400ppm).
- The sensor is prohibited to use wave peak depth.
- When welding with iron, set the temperature to (350±5) degree, early
- The pick-up time must be less than 35.
- When using the sensor, it is recommended that the customer use the method of inserting the solder bump to directly insert and remove the sensor for toilet maintenance.
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