CO2 and TVOC Concentration Detector - Based on AIR001

Project Description & Related Functions
: The main controller uses AIR001,
and the TVOC and CO2 concentration data are measured via SGP30.
An IP5407 charge/discharge chip is used (this chip is always on at 5V, so there's no need to worry about it being shut down due to low power consumption).
The cost is around 50 (the SGP30 sensor alone costs 28; there probably aren't any cheaper sensors that can measure CO2...)
 
. LEDs display the battery status, four-digit (CO2 or TVOC) readings, and four indicator lights (preheat, TVOC display, CO2 display, and warning for exceeding measurement limits). You can solder the corresponding colors according to your preference or the silkscreen instructions.  
The four resistors below the LEDs can be soldered with 500Ω-1K resistance; the higher the resistance, the lower the brightness.
 
Here, you can solder a 3-pin female connector to GND, TX, and RX, and solder a DuPont wire with a female connector to 3V3 for direct insertion into DAPlink for programming.
The pad to the right of 3V3 is RST; be careful not to bridging it. The BOOT button is located at the top left of the board (U14).
 
It is recommended to solder it flat as shown in the image, using minimal solder. After programming, you can directly remove the header.
 
 
For IP4057 and its peripheral circuitry, it is recommended to solder the middle pad (GND) only after programming and verifying the CO2 measurement function is normal.
A hole has been made; if you don't have a heating plate or hot air gun, you can use a soldering iron to heat it and pour solder in from the back (if using a heating plate or hot air gun, it is recommended to remove this large hole to prevent cold solder joints). Detailed
data for IP4057 can be found in the documentation; pages 8-9 of the LED display description are copied here. This project is licensed under CC-BY-NC-SA 4.0. The code references the Adafruit_SGP30 library for obtaining SGP30 readings and calibration. The peripheral circuitry of IP5407 in the SGP30 schematic is modified from the project "5V Charging/Discharging Module IP5407". The SGP30 adapter board is inspired by @yanshimi's portable WIFI adapter board project . This is the first public release of this project; it is my original work. This project has not won any awards in other competitions. (This project has not participated in any other competitions) Project Progress 2024.4.2 and earlier: This page was created, and the schematic diagram, PCB design, and first version of the soldering code were completed and all ran normally. 2024.4.7: The outer shell is finished. Here are some renderings (awaiting prototyping). 2024.4.10: Updated physical images. 2024.6.20: Improved the description , added acrylic panel design principle & software description. The TVOC and CO2 concentration data measured by SGP30 are obtained through AIR001 and displayed on a four-digit PCB digital tube. After startup, the TVOC and CO2 concentration are checked once per second. If either value is too high, a warning light and the corresponding over-limit indicator light will light up (for example, if CO2 exceeds the limit, the CO2 indicator light and the warning light will flash simultaneously once per second). After startup, if the BOOT button is pressed briefly in the upper left corner of the board (U14), the current measurement value will be displayed for 5 seconds and the corresponding value indicator light will be lit. At this time, the value and display content will still be refreshed every second. If you press BOOT briefly again at the 2nd, 3rd, or 4th second, the display will switch to another value (e.g., after a short press of BOOT, the CO2 concentration measurement value will be displayed and the CO2 indicator light will illuminate; pressing it again after 2 seconds will switch to the TVOC concentration measurement value, at which point the TVOC indicator light will illuminate). After startup, if you press and hold BOOT for more than 4 seconds, the indicator light will remain constantly on and the measurement value will be refreshed. Pressing it briefly again will turn off the constant illumination. The SGP30 sensor needs to warm up each time it starts (about half a minute), so a startup animation has been made. After startup, placing the sensor in a well-ventilated area for a while will provide more accurate readings. When using battery power, connecting an external power source will not cause the main controller to restart (but disconnecting the external power source will most likely cause a restart, due to IP4057 characteristics). Physical demonstration: First generation - standby mode (the power indicator light was too bright, so a lot of solder resist was applied to block the light). First generation - displaying CO2 concentration (476ppm). Notes: Try to buy IP4057 chips from reputable sources. The chips I initially bought on Taobao stopped working after a while; replacing them with those from LCSC Mall fixed the problem. Acrylic panels are slightly expensive; you can selectively order them or integrate them into other large boards, or use a PCB instead (the effect will be slightly worse). Other source code is in the attachment; please use Arduino to program it yourself.