#7th LCSC Electronics Contest# Eight-in-One Environmental Testing

* 1. Project Function Introduction: This project

can detect formaldehyde, CO2, TVOC, PM2.5, PM10, temperature, humidity, and ionizing radiation. It uses an N32G430C8L7 as the main control chip, an ESP12 as a Wi-Fi module for network connection, an e-ink display using SPI communication, a seven-in-one air quality transmitter connected via serial port, a Geiger counter sampling via ADC, and a built-in 18650 battery allowing for mobile detection. Charging is via a Type-C interface.
 
* 2. Project Attributes

: This is the first time this project has been publicly disclosed; the project has referenced other projects; the project has not won any awards in other competitions, and the project has not been defended at the school.
 
* 3. Open Source License

GPL3.0
 
* 4. Hardware

Component Selection Principles: While ensuring normal functionality, select components of the same model as much as possible to reduce the cost per unit (e.g., 22uH inductor, MMBT3904 transistor, CJ3400 MOSFET, etc.).
 
Hardware Circuit Notes: 
1. Power Supply Circuit
: 1. Select ME6211 C30 or higher (A suffix indicates different package sizes). The maximum operating current varies depending on the suffix; please refer to the relevant manual.
2. The 100uF capacitor can be modified or removed based on cost (the first version used 1117, this tantalum capacitor is a legacy), keeping it is better.
 
2. E-ink Screen Circuit:
1. The inductor model can be smaller; please refer to the official circuit.
2. The e-ink screen interface header is 24-pin.
3. This project uses a Zhongjingyuan 2.9-inch e-ink screen.
 
3. MCU Circuit:
1. Use 0201 pads to bring out the BOOT and RST pins instead of shorting them.
2. Pin compatibility with STM32F103C8T6 (but STM32 program not written).
 
4. Geiger transistor circuit
: 1. Due to the high cost and scarcity of the 060S-045 transformer, I actually used the 060S-058, turns ratio 1:18, 120uH.
2. Measure the voltage across C36, rotate potentiometer R29 to fine-tune the output voltage to 400V. If the voltage is insufficient, reduce the resistance of R31.
3. HV_SD is the boost enable pin. If the microcontroller control pin cannot control the enable, remove the 0 ohm pin and abandon the enable function.
4. After completing the board, I realized the LM3481 is too expensive. If possible, I suggest choosing other Boost converter chips as alternatives, even a 555 would be fine.
 
 
*5. The software

related to ESP12F functions is not yet complete. N32 code will be released after ESP12F is completed.
 
*6. BOM List:

The BOM list only includes model and package information and is for reference only; it cannot be used for one-click ordering from the marketplace. 
 
*7. Competition Logo Verification:

 Logo faceplate
 
assembly
 , back assembly
 
, front assembly.
 
Since 3D printers cannot be placed in school dormitories, we will not include a casing.