HCHO-SENSOR

More and more people are paying attention to formaldehyde pollution when renting or renovating new homes. The dangers of formaldehyde are well-known; it is colorless and odorless, making it undetectable by human senses. Commercially available formaldehyde testing instruments vary greatly in quality, and their measurement results are often unreliable. This design utilizes a high-precision electrochemical formaldehyde sensor, factory-calibrated to ensure reliable and consistent measurement results. Based on the ESP32 platform, it communicates with the formaldehyde sensor, storing the acquired data in Flash memory. An LCD screen enables human-computer interaction, displaying real-time formaldehyde measurements. Alarm thresholds can be set via a GUI, historical sampling values ​​can be viewed, and data can be uploaded to a cloud server for permanent storage. It can also be integrated into smart home systems, linking with devices such as air conditioners and fans.
1. Overall Appearance:
From right to left on the front, the components are: USB-Type-C port, download/reset button, OLED display, and HCHO sensor.
2. Function Introduction
: The device starts working immediately upon plugging in the USB-Type-C port and powering on. The OLED display shows the formaldehyde content value output by the HCHO sensor on the first line. The second, third, and fourth lines show the serial data received by the processor, allowing for easy monitoring of serial communication with the HCHO sensor.
The fifth line displays the maximum measured formaldehyde content value. The reset button clears this information.
3. Hardware Introduction
: HCHO Sensor: The DS-HCHO is a highly integrated, high-precision, and highly stable digital output formaldehyde sensor. It uses an electrochemical method to detect formaldehyde content in real time under various application scenarios. It features accurate measurement, small size, and ease of use, making it suitable for both home and industrial applications. It can also be applied to various media such as automobiles, air conditioners, and televisions.
2.1 Processor
: The processor used is the ESP32-C3, which is compact, powerful, and has WiFi RF capabilities, offering various programming methods.
3. Software Design:
 
The ESP32 send query command code
module returns a total of 10 bytes, defined as shown in the diagram above. ESP32 receiver program:
Formaldehyde calculation formula:
4. Effect Test:
During the test, a lighter is used to spray gas at the sensor, and the numerical changes can be observed. The maximum value is recorded on the screen.
 
The video is attached .