pavax / cubecell_outdoor_sensor

Cubecell Lorawan Weather Station

Setup

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.

• https://resource.heltec.cn/download/CubeCell/HTCC-AB02/HTCC-AB02_PinoutDiagram.pdf

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

• 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

Javascript Uplink Decoding

 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;
  }

Downlink Commands

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	-