Microcontroller
I'm using the Heltec Cubecell AB-02 Microcontroller. It is fantastic for outdoor Lorawan projects as it consumes only 10uA when it sleeps and comes out-of-the-box with a solar-charging capability. It also has a build in mechanism (High-Side Mosfet Switch) to turn the power-line to the sensors on and off.
Sensors
This project uses the following sensors:
-
MB7374: Ultrasonic Distance Sensor
- Used to measure the snow-depth
- Protocol: Serial
- https://maxbotix.com/products/mb7374
-
RG-15: Rain Sensor
- This is an optical rain tipping bucket sensor. It measures the amount and intensity of rain.
- Protocol: Serial
- https://rainsensors.com/products/rg-15/
-
Wind Speed Sensor
- The Wind-Speed is measured every 60sec. The median and max values are then send at every duty cycle.
- Protocol: Analog 0-4V (Needs voltage divider to output max 2.4V for the adc input)
- https://www.aliexpress.com/item/1005002627447076.html
- The Wind-Speed is measured every 60sec. The median and max values are then send at every duty cycle.
-
Wind Direction Sensor
- Protocol: Analog 0-5V (Needs voltage divider to output max 2.4V for the adc input))
- https://www.aliexpress.com/item/1005006845253011.html
-
SHT-40: Temperatur and Humidity Sensor
- Protocol: I2C
-
BME-280: Temperatur, Humidity and Pressure Sensor
- Protocol: I2C
function parse(payloadHex, port) {
function hexToBytes(hex) {
for (var bytes = [], c = 0; c < hex.length; c += 2)
bytes.push(parseInt(hex.substr(c, 2), 16));
return bytes;
}
function calculateDewPoint(temperature, humidity) {
// Constants for the Magnus-Tetens approximation
const a = 17.27;
const b = 237.7;
// Calculate alpha
const alpha = ((a * temperature) / (b + temperature)) + Math.log(humidity / 100);
// Calculate the dew point
let dewPoint = (b * alpha) / (a - alpha);
// Round to two decimal places
dewPoint = Math.round(dewPoint * 100) / 100;
return dewPoint;
}
var bytes = hexToBytes(payloadHex);
let msg = {};
msg.counter = (bytes[0] << 8) | bytes[1];
msg.batteryVoltage = (bytes[2] << 8) | bytes[3];
msg.temperature = (bytes[4] << 24 >> 16 | bytes[5]) / 100; // signed
msg.humidity = ((bytes[6] << 8) | bytes[7]) / 100;
msg.distance = (bytes[8] << 8) | bytes[9];
msg.windVoltage = (bytes[10] << 24 >> 16 | bytes[11]); // signed
msg.windVoltageMax = (bytes[12] << 24 >> 16 | bytes[13]); // signed
msg.rainEventCounter = (bytes[14] << 8) | bytes[15];
msg.rainAcc = ((bytes[16] << 8) | bytes[17]) / 100;
msg.rainEventAcc = ((bytes[18] << 8) | bytes[19]) / 100;
msg.rainTotalAcc = ((bytes[20] << 8) | bytes[21]) / 100;
msg.rainRInt = ((bytes[22] << 8) | bytes[23]) / 100;
msg.rainSerialCode = bytes[24];
msg.rainLastDetection = (((bytes[25] << 24) | (bytes[26] << 16) | (bytes[27] << 8) | bytes[28]));
msg.windDirection = bytes[29];
msg.temperature2 = (bytes[30] << 24 >> 16 | bytes[31]) / 100; // signed
msg.humidity2 = ((bytes[32] << 8) | bytes[33]) / 100;
msg.pressure = ((bytes[34] << 24) | (bytes[35] << 16) | (bytes[36] << 8) | bytes[37]) / 100;
msg.dewPoint = calculateDewPoint(msg.temperature, msg.humidity);
return msg;
}
Important: Send Payload withouth the '0x' prefix.
| Port | Command | Payload Examples |
|---|---|---|
| 4 | Set the Duty Cycle Time [seconds] | 0x003C -> every 1 minute 0x0078 -> every 2 minutes 0x012C -> every 5 minutes 0x0258 -> every 10 minutes 0x0384 -> every 15 minutes 0x04B0 -> every 20 minutes |
| 5 | Turn the RGB Light on/off | 0x1111 -> turn the light on 0x0000 -> turn the light off |
| 6 | Send a Serial-Command to the Rain Sensor | 0x006B -> send the 'k' command |
| 7 | Set the background measurements interval time [seconds] | 0x001E -> every 30 seconds 0x003C -> every 1 minute 0x0078 -> every 2 minutes |
| 9 | Restart the Microcontroller | - |