📚 Table of Contents

• [[#🧰 Parts List]]

• [[#ESPHome Configuration]]

• [[#📡 ESPHome Sensor Station Entities]]

  • [[#🌡️ Environmental Sensors]]
  • [[#⚡ Power & Energy Monitoring]]
  • [[#📶 WiFi Signal Strength]]
  • [[#🎛️ Switches & Buttons]]

• [[#⚡ Daily Energy Use Summary]]

  • [[#Base System (5-minute wake cycle)]]
  • [[#With PMS5003 Included]]
  • [[#With OLED Usage (occasional manual activation)]]

• [[#☀️ Solar Power Summary]]

  • [[#🔋 + ☀️ Battery Backup & Solar Requirements]]

• [[#ESP32-C3 SuperMini GPIO Pinout Plan]]

• [[#💤 Deep Sleep and Power Management]]

  • [[#🔌 Devices Powered Down During Deep Sleep]]
  • [[#🔓 Wake Lock Behavior]]
  • [[#👆 Display Button Behavior]]
  • [[#💤 Smart Sleep Behavior]]
    • [[#Wake Timing]]
    • [[#Smart Sleep Timing]]
    • [[#Preparing for Sleep]]
    • [[#Smart PMS Control]]

• [[#🧾 Bill of Materials (BOM Summary)]]

  • [[#Microcontroller & Power]]
  • [[#Sensors]]
  • [[#Display & Interface]]
  • [[#Power Management]]
  • [[#Passive Components]]
  • [[#Optional Components]]
  • [[#Downloadable BOM Formats]]

• [[#📦 Case and Assembly]]

  • [[#3D-Printed Enclosure]]
  • [[#PCB Design]]
  • [[#Assembly Instructions]]

• [[#✅ Conclusion]]

🧰 Parts List

ESPHome Configuration

YAML configuration for the Sensor Station
is provided in this repository.

This will configure the ESPHome firmware for the sensor station.

See ESPHome documentation for more details
on how to set up and use ESPHome.

Configuring Secrets

The firmware will reference a secrets.yaml file for sensitive information.
Naturally, that file should not be included in this repository.

However an example file is provided as secrets.yaml.example
for reference.

You should create a new file called secrets.yaml in the same directory
as the sensor-station.yaml file.

Then, using the example as a guide, fill in the required information.

Your WiFi credentials go in the wifi_ssid and wifi_password fields.

Optionally, you can provide a backup_wifi_ssid and backup_wifi_password.
(See the note on line 17 of the sensor-station.yaml file to enable this.)

You may choose an ota_password for over-the-air updates, or leave it blank.

You may also choose a hotspot_password for the fallback hotspot, or leave
it blank for no password.

The api_encryption_key must be a 32-byte base64 encoded string.
You can find a randomly generated key
in the ESPHome documentation.

This key is used during the station setup in Home Assistant to encrypt
the API communication between the ESP32 and Home Assistant.

📡 ESPHome Sensor Station Entities

🌡️ Environmental Sensors

• Ambient Light
• Ambient Temperature
• Ambient Humidity
• BMP280 Temperature
• Atmospheric Pressure
• Enclosure Internal Temp
• Pond Water Temperature
• Water Level Distance
• Actual Water Level (calculated from ultrasonic)

⚡ Power & Energy Monitoring

• Battery Voltage
• Battery Current
• Battery Power
• Battery Percentage (calculated)
• Solar Voltage
• Solar Current
• Solar Power
• Estimated Total Power Use (solar in – battery out)
• Estimated Total Current Use (net amps)
• Total Energy Used Today (Wh)
• Total Current Today (Ah)
• Total Energy Used (All-Time, Wh)
• Total Current Used (All-Time, Ah)
• Solar Energy Collected Today (Wh)
• Solar Current Today (Ah)
• Solar Energy Collected (All-Time, Wh)
• Solar Current (All-Time, Ah)

🌫️ Air Quality

• PM1.0
• PM2.5
• PM10.0

📶 WiFi Signal Strength

• WiFi Signal dB (RSSI)
• WiFi Signal Percent (converted)

🎛️ Switches & Buttons

• Wake-Lock (prevents deep sleep)
• Force Long Sleep
• Force Short Sleep
• PMS Sensor Power (MOSFET)
• Internal Heater (MOSFET)
• Sensor Power Rail (MOSFET)
• OLED Display Power (MOSFET)
• OLED Activate Button (momentary input)

🌡️ Enclosure Climate Control

• Enclosure Heater Control (thermostat with presets)

⚡ Daily Energy Use Summary

Base System (5-minute wake cycle)

• ESP32-C3 (deep sleep): ≈0.01mA × 23.6h ≈ 0.24mAh/day

• ESP32-C3 (active): ≈25mA avg × 5s per wake × 288 wakes = 10.0mAh/day

• Sensors (active during wake):

  • AHT20/BMP280, HC-SR04, DS18B20, INA219s, TMP102, etc.
    ≈ 15.05mA combined × 5s × 288 = 6.01mAh/day

• TEMT6000 (brief read): negligible (included above)

• OLED (off by default): 0mAh/day (fully unpowered unless activated manually)

• Subtotal without PMS5003 or OLED usage:
  → ≈16.25mAh/day

With PMS5003 Included

• PMS5003 sleep: ≈1mA × 24h = 24mAh/day
• PMS5003 active: ≈100mA × 5s × 288 = 40mAh/day
• New total with PMS5003:
  → ≈80.05mAh/day

With OLED Usage (occasional manual activation)

Assuming:

• OLED on for 15s × 10 button presses per day
• OLED draw ≈ 12mA

→ 12mA × (15s × 10) / 3600s = ≈0.5mAh/day

• Base system + TMP102 + OLED use:
  → ≈16.75mAh/day

☀️ Solar Power Summary

• Panel Output: 5V @ 200mA
• Estimated good sunlight: 4h/day
• Daily energy input: ≈800mAh raw, ≈400mAh effective
• Conclusion: More than sufficient to offset daily usage,
  even in winter/cloudy days

🔋 + ☀️ Battery Backup & Solar Requirements

With 3000mAh LiPo and 5V 200mA Solar Panel

ESP32-C3 SuperMini GPIO Pinout Plan

These color assignments are not electrically required but help reduce
wiring mistakes during assembly.

💤 Deep Sleep and Power Management

The ESP32-C3 enters deep sleep between sensor readings to conserve energy.
In this state, the main processor halts and only the RTC (real-time clock)
memory and wake-up timer remain powered.
This reduces current consumption to as low as 5µA,
making deep sleep essential for maintaining long battery life in
solar-powered deployments.

During deep sleep, most GPIO pins are inactive, and peripheral
devices are unpowered unless explicitly designed to stay on.

🔌 Devices Powered Down During Deep Sleep

The following components are fully powered off
while the ESP32-C3 is in deep sleep:

• SH1107 OLED Display
  Powered via a GPIO-controlled MOSFET, only powers on with button press
• AHT20 + BMP280 Combo Sensor
  On the I²C sensor power rail
• TMP102 Temperature Sensor
  Shares the I²C power rail
• TEMT6000 Light Sensor
  Powered via sensor rail, inactive during sleep
• HC-SR04 Ultrasonic Sensor
  Powered by sensor rail, to avoid idle current
• PMS5003 Air Quality Sensor
  Powered via a GPIO-controlled MOSFET
• DS18B20 Temperature Probe
  Powered off via sensor rail
• PI Heating Element
  Powered via a GPIO-controlled MOSFET, not energized except
  during extreme cold during wakes
• Wi-Fi Radio
  Disabled automatically in deep sleep mode

Only the battery-backed RTC and wake timer remain active.

🔓 Wake Lock Behavior

A wake lock can temporarily prevent the ESP32-C3 from
returning to deep sleep.
This mechanism is useful for debugging, testing, or when extended uptime
is required (e.g. for screen visibility or serial logs).

When a wake lock is active, the OLED display shows a clear full-screen message:

WAKE
LOCK

This mode takes priority over the normal page-based display logic,
ensuring the user is alerted whenever the wake lock is engaged.
The message uses a large font and occupies the full screen for visibility.

👆 Display Button Behavior

The OLED remains off by default and only lights up on button press.
It is automatically turned off after a brief timeout to preserve energy.

💤 Smart Sleep Behavior

The system uses a script-based approach to determine when and how long to enter
deep sleep, with logic based on wake-lock state,
battery voltage, and solar input.

Wake Timing

An initial delay of 30s occurs at the start of wake/boot
when the PMS5003 is enabled.
This allows the PMS5003 to stabilize before taking readings.

After the initial wake-up (or boot-up) the smart sleep script is executed.

Smart Sleep Timing

This script dynamically chooses a sleep duration
based on current power conditions:

• If wake_hold_switch is on,
  the system logs the event and skips sleep.

• Otherwise, it evaluates:

  • If force_long_sleep is on,
    the system enters long sleep (30 minutes).
  • Else if force_short_sleep is on,
    it enters short sleep (30 seconds).
  • Else:
    • If battery voltage is above 3.7V
      and solar input is above 50 mA,
      it chooses a short sleep duration (5 minutes).
    • If not, it defaults to long sleep (30 minutes).

• After setting the sleep duration,
  the system remains awake for a short time
  to allow sensors to stabilize before sleeping:

  • If the PMS5003 air sensor is powered, it waits 30 seconds.
  • Otherwise, it waits 10 seconds.

• If wake-lock is not active,
  the script initiates deep sleep after the delay.

  Summary:

  wake_hold_switch has the highest priority and will prevent sleep
  until the lock is released.

  force_long_sleep has the second highest priority and will
  change sleep timing to 30 minutes.

  force_short_sleep has the lowest priority and will
  change sleep timing to 30 seconds.

  After these initial switches are evaluated,
  if none are enabled then the system will evaluate the battery voltage
  and solar input to determine the sleep duration.

  If the PMS5003 sensor is enabled,
  wake time is extended by 30 seconds
  to allow the sensor to stabilize before sleeping.

Preparing for Sleep

This script ensures all major components are powered down
before entering deep sleep.

Actions:

• Logs the transition to sleep.
• Powers off:
  • OLED display
  • PMS5003 sensor
  • Shared sensor rail
  • Internal heater
• Delays 100ms for power-down settling.
• Initiates deep sleep.

Smart PMS Control

The PMS5003 is relatively power-hungry, so it is only powered on
when conditions are favorable.
The PMS5003 uses ~80–100 mA when measuring and ~20–30 mA in its idle state.

This script decides whether to power the PMS5003 sensor
based on power availability.

• If battery is above 3.6V or solar current is above 20 mA,
  the PMS sensor is powered on.
• Otherwise, it remains off to conserve energy.

🧾 Bill of Materials (BOM Summary)

Microcontroller & Power

• 1× ESP32-C3 SuperMini
• 1× CN3065 Solar Charging Module
• 1× 3000mAh LiPo Battery
• 1× 5V 200mA Solar Panel

Sensors

• 1× AHT20 + BMP280 (combined I²C PCB)
• 1× TMP102 (I²C internal temp)
• 1× DS18B20 (1-Wire, waterproof)
• 1× TEMT6000 (analog light sensor)
• 1× HC-SR04 (ultrasonic distance)
• 2× INA219 (voltage/current monitoring)
• 1× PMS5003 (air quality sensor, optional)

Display & Interface

• 1× SH1107 OLED Display (128x128 I²C)
• 1× Momentary button (for OLED activation)

Power Management

• 1× PI Heating Element (5V, 1W)
• 3× STP55NF06L N-MOSFETs (OLED + Heater switching)

Passive Components

• 3× 4.7kΩ Resistors (1/4W)
  • 2 for I²C pull-ups (SDA + SCL shared across all I²C devices)
  • 1 for DS18B20 1-Wire pull-up
• 1× 470µF Electrolytic Capacitor (≥6.3V) – Bulk decoupling (for ESP32 VIN)
• 1× 100nF Ceramic Capacitor (≥50V) – High-frequency filtering
  (ESP32 + sensor power rails)

Optional Components

• Assorted hookup wires (solid or stranded) for interconnections
• Custom PCB or perfboard for permanent soldered assembly
• Connectors (e.g. JST-PH, JST-XH, Dupont, terminal blocks) for modular assembly
• Heat-shrink tubing or silicone wire sleeving for strain relief
• Mounting hardware or standoffs for enclosure assembly
• 1× 3D-printed or waterproof case
• 1× Heatsink pad or thermal tape (for PTC heater to LiPo)
• 1× GPIO expander (not needed in current design)

Downloadable BOM Formats

• CSV
• JSON

Case and Assembly

An optional 3D-printable enclosure and PCB design will be provided later.
Assembly instructions using those components will be provided later.

3D-Printed Enclosure

A 3d-printed enclosure is used to house the components.

Although optional, using this enclosure is recommended for best performance.

This design will provide acceptable waterproofing and
protection from the elements while still allowing the sensors
to access the ambient temperature, humidity, light, and
particulate matter.

A section of the enclosure will require additional insulation
to help maintain the internal temperature of the LiPo battery
and PMS5003 sensor.

The model and STL files for the enclosure will be provided
at a later date.

PCB Design

An optional custom PCB board design allows simple assembly
and compact building of the sensor station.

Some PCBs will be available for purchase, but the design files
will also be provided for those who wish to build their own.

Soldering is still required, but the PCB design will allow for
easy installation of the soldered components like
MOSFETs, resistors, and connectors.

Alternatively, you can simply assemble the station using wires and no PCB.

All of the components use through-hole soldering,
so no special tools or skills are required.

The PCB designs will be available at a later date.

Assembly Instructions

Assembly instructions will show how to assemble the station using
the printed enclosure and PCB.

These instructions will be provided at a later date.

✅ Conclusion

• The system is extremely energy efficient in typical operation
  (≈16–17mAh/day), easily supported by a 3000mAh battery.
• A single 5V 200mA solar panel can fully offset even the
  highest power use case (≈280mAh/day) with just 1.5 hours of sunlight/day.
• The design remains solar-sustainable year-round, including
  during cold winter conditions with heater usage.
• A low-power PTC heater and internal TMP102 temperature sensor
  allow safe LiPo and PMS5003 operation below freezing.
• The OLED display is manually activated and powered via MOSFET,
  avoiding idle drain and preserving battery life.
• All components are powered efficiently via GPIO-controlled switches,
  using MOSFETs to manage loads above safe GPIO sourcing limits.
• All necessary functionality—including sensors,
  power switches, UART, and buttons—was
  achieved using the ESP32-C3 SuperMini's onboard GPIOs,
  with no GPIO expander required.