STM32 High-Precision Environmental Monitoring Station

A high-precision environmental monitoring station based on STM32 + PlatformIO + Arduino framework, integrating:

• 🌡 SHT85 – temperature & humidity
• 🌬 BMP390L – high-resolution barometric pressure
• 🌫 Sensirion SPS30 – particulate matter (PM1.0 / PM2.5 / PM4.0 / PM10)
• ☢ Geiger counter – real-time radiation monitoring
• 🔗 Binary serial protocol with checksum & sync word

Designed for long-term unattended operation, high stability, and easy integration with SBCs / servers.

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✨ Features

• High-accuracy environmental sensing (industrial-grade sensors)
• UART-based SPS30 with automatic fault detection & recovery
• Interrupt-driven Geiger counter pulse counting
• Fixed-period logging with CPM → µSv/h conversion
• Compact binary output (low bandwidth, low latency)
• PlatformIO-based, reproducible build environment
• Suitable for meteorological, radiation, and environmental monitoring projects

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🧰 Hardware Requirements

Core MCU

• STM32 (tested on STM32F1 series, e.g. Blue Pill / STM32F103)

Sensors

Sensor	Interface	Notes
SHT85	I²C	High accuracy temp & RH
BMP390L	I²C	Pressure oversampling ×32
SPS30	UART (115200 8N1)	PM sensor (UART mode)
Geiger Tube	GPIO interrupt	Falling-edge pulse counting

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🔌 Pin Mapping (Default)

I²C

Signal	Pin
SDA	PB7
SCL	PB6

SPS30 (UART)

SPS30	STM32
TX	PA3
RX	PA2

HardwareSerial Serial2(PA3, PA2);

Geiger Counter

Signal	Pin
Pulse	PA0 (EXTI)

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📦 Software Stack

• PlatformIO
• Arduino framework for STM32
• Libraries:
  • SHTSensor
  • Adafruit_BMP3XX
  • SensirionUartSps30

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⏱ Sampling & Timing

Item	Value
Log period	60 s
SPS30 warm-up	~1.2 s
I²C clock	100 kHz
UART timeout	5 s

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📡 Serial Output Protocol

Binary stream over USB Serial (Serial):

Sync word: 0x8A

Payload structure: float data[8] + uint8_t checksum

Data layout: 0 Temperature (°C)
1 Humidity (%RH)
2 Pressure (hPa)
3 Radiation (µSv/h)
4 PM1.0 (µg/m³)
5 PM2.5 (µg/m³)
6 PM4.0 (µg/m³)
7 PM10 (µg/m³)

Checksum: XOR of all payload bytes (float array only).

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☢ Radiation Calculation

µSv/h = CPM / 153.8

Note: conversion factor depends on Geiger tube model.

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🛠 SPS30 Reliability Strategy

• Automatic retry on read failure
• Consecutive failure detection
• Automatic stop/start reinitialization
• Cool-down recovery window