Weather Station Transmitter

Weather Station based on HC12 transceiver

About
Features
Bill of Materials
Libraries
Getting Started
Description
Changelog
Task list
Pictures

" class="reference-link">1. About

Weather Station powered by 18650 Li-ion battery, charged by solar panel. 433MHz HC-12 module is used to send data formatted in JSON. The project is a part of bigger IOT system, and is related to my other projects:

" class="reference-link">2. Features

Various sensors - temperature, humidity, pressure, light intensity, UV index, PM2.5, PM10
Battery and solar panel voltage measurements
Possibility to add more sensors (e.g. by I2C)
Deep sleep to save power
Debug mode

" class="reference-link">3. Bill of Materials

Main components:

Device	Description	Price
Arduino Nano V3	Main IC (clone)	$2.50
BME280	Temperature, humidity, pressure sensor	$2.10
MCP9808	High accuracy temperature sensor	$0.75
BH1750	Light sensor	$1.00
SI1145	UV index sensor	$3.70
PMS3003	Dust sensor	$13.40
HC12	433MHz transceiver	$1.95
J5019	Battery charger with DC-DC converter	$0.69
2000mAh Li-Ion	18650 Battery	$2.20
18650 holder	18650 Battery holder	$0.35
PC,B	Custom PCB
Housing	Custom housing (3D printed)

" class="reference-link">4. Libraries

" class="reference-link">5. Getting Started

To run Weather Station, user should change some settings:

Node ID - used to identify device by receiver

#define NODE_ID           103   // Device ID, for internal purpose

Sleep time - how often device will wake up and send measurements

#define SLEEP_TIME        37    // x * 8s = sleep time

Calibration factors - booth should be 1.0 at the beginning, later can be adjusted to fit measured voltages to real values

#define BAT_FACTOR        0.979981    // a = y/x, calibration factor
#define PAN_FACTOR        0.986017    // a = y/x, calibration factor

Altitude - set real value of your location, used for pressure readings

#define ALTITUDE        515.0 //define altitude of location

" class="reference-link">6. Description

Measurements

Temperature: measured by MCP9808 to ensure high accuracy (0,25ºC)
Humidity, Pressure: measured by BME280
Light: measured by BH1750 (lux)
UV index: measured by SI1145
PM2.5, PM10: measured by PMS3003
Voltages: battery and solar panel voltages measured by analog inputs

Output Parameters

Measurements send by device using HC-12:

{
  "id":103,
  "te":4,       // temperature
  "hu":72,      // humidity
  "pr":1024.8,  // pressure
  "p2":34,      // PM2.5
  "p1":45,      // PM10
  "ba":4.07,    // battery voltage
  "pa":4.794    // solar panel voltage
}

" class="reference-link">7. Changelog

2021-04-09 V1.0 Stable version

" class="reference-link">8. Task list

Software:

Service commands (receive data, e.g. calibration factors, sleep time and store in EEPROM)

Hardware:

Add additional capacitor to Vcc for better stability
Change MOSFET circuit - Q1 should be connected to GND, add gate-source resistor
For future - add anemometer, rainmeter, wind direction etc.