LiDAR Snow Depth Measurements

Hardware

• Garmin LIDAR-Lite v4 LED - Distance Measurement Sensor
• SparkFun IoT RedBoard ESP32 Development Board

Setup

Red Board

The software to run the LiDAR from the RedBoard is contained within the src/lidar/lidar.ino file. This file should be uploaded to the board using the Arduino IDE, refer to the SparkFun hookup guide for installing the software and uploading to the board.

Before uploading, configure the lidar.ino file by setting the following variables:

Required Variables

• API_SERVER - Location for the RedBoard to send data to via POST.
• WIFI_SSID and WIFI_PASSWORD - SSID and password for the Wi-Fi network the RedBoard should connect to.

Optional Variables

• LIDAR_CONFIG = 0; // LiDAR setting
• LIDAR_CALIBRATION = 0.0; // Error of the LiDAR sensor
• NUM_MEASUREMENTS = 60; // Number of measurements to take for average
• MEASUREMENT_INTERVAL = 1000; // Interval between Lidar measurements in milliseconds (adjust as needed)

Data Server

The data server will be the device that receives the POST request from the RedBoard from the src/server.py script. If using WeeWx, this should be the device with your WeeWx installation. The script will listen on port 7070 by default for data from the sensor, then write reach POST to a csv database.

Server Dependencies

• Python 3.9 or higher
• Pandas

Server Usage

The server script supports the following command line arguments:

• --path DIRECTORY: Specifies the data directory for the API and archive data. This directory will be created if it does not exist.
• --port [PORT]: Optional. Specifies the port number to run the server on. If not provided, the default port 7070 will be used.

Example Usage: python src/server.py --path /path/to/data/ [--port 7070]

WeeWx Configuration

1. Add the five new elements to the WeeWx database.

   ./weewx/bin/wee_database --add-column=lidar_distance --type=REAL
   ./weewx/bin/wee_database --add-column=lidar_snowdepth --type=REAL
   ./weewx/bin/wee_database --add-column=lidar_snowfall --type=REAL
   ./weewx/bin/wee_database --add-column=lidar_boardtemp --type=REAL
   ./weewx/bin/wee_database --add-column=lidar_signal --type=REAL
   

2. Define the units for the elements by adding the code below to the WeeWx extension file at weewx/bin/user/extensions.py.

   import weewx.units
   weewx.units.obs_group_dict["lidar_snowdepth"] = "group_rain"
   weewx.units.obs_group_dict["lidar_snowfall"] = "group_rain"
   weewx.units.obs_group_dict["lidar_distance"] = "group_rain"
   weewx.units.obs_group_dict["lidar_boardtemp"] = "group_temperature"
   

3. Copy the LiDAR StdService to the weewx user scripts directory.

   cp src/weewx/lidar_snow.py weewx/bin/user/.
   

4. Add the service to your WeeWx config file under [Engine] > [[Services]] > data_services.

   data_services = user.lidar_snow.AddLidarSnowData
   

5. Add the following code to the end of your WeeWx config file and enter values for each.

   ##############################################################################
   
   #   This section configures the LiDAR snow depth ingest.
   
   [SnowDepthLiDAR]
   
       api_directory = !** Enter the path to the API directory **!
       stale_minutes = 2
       sensor_id = !** Enter the MAC address (without the :) of the sensor **!
       sensor_datum = !** Enter the height of the sensor above ground in cm **!
   

6. Copy the cheetah report templates into the Seasons skin.

   cp src/weewx/lidarsnow.html.tmpl weewx/skins/Seasons/.
   cp src/weewx/lidarsnow.inc weewx/skins/Seasons/.
   

7. Add #include "lidarsnow.inc" line to the widget_group div within the weewx/skins/Seasons/index.html.tmpl file.

      <div id="widget_group">
        #include "current.inc"
        #include "lidarsnow.inc"
        #include "radar.inc"
        #include "satellite.inc"
        #include "sunmoon.inc"
        #include "hilo.inc"
        #include "sensors.inc"
        #include "about.inc"
        #include "map.inc"
      </div>
   

8. Add the following to the day, week, month, and year plots within the skin configuration file at the weewx/skins/Seasons/skin.conf.

    [[day_images]]
   
        [[[day_lidarsnowfall]]]
            yscale = 0.0, None, 0.5
            plot_type = bar
            [[[[lidar_snowfall]]]]
   
        [[[day_lidarsnowdepth]]]
            yscale = 0.0, None, 0.5
            plot_type = bar
            [[[[lidar_snowdepth]]]]
   
        [[[day_lidardistance]]]
            yscale = None, None, 1.0
            plot_type = bar
            [[[[lidar_distance]]]]
   

   [[week_images]]
   
      [[[week_lidarsnowfall]]]
         yscale = 0.0, None, 0.5
         plot_type = bar
         [[[[lidar_snowfall]]]]
      
      [[[week_lidarsnowdepth]]]
         yscale = 0.0, None, 0.5
         plot_type = bar
         [[[[lidar_snowdepth]]]]
      
      [[[week_lidardistance]]]
         yscale = None, None, 1.0
         plot_type = bar
         [[[[lidar_distance]]]]
   

   [[month_images]]
   
      [[[month_lidarsnowfall]]]
         yscale = 0.0, None, 0.5
         plot_type = bar
         [[[[lidar_snowfall]]]]
      
      [[[month_lidarsnowdepth]]]
         yscale = 0.0, None, 0.5
         plot_type = bar
         [[[[lidar_snowdepth]]]]
      
      [[[month_lidardistance]]]
         yscale = None, None, 1.0
         plot_type = bar
         [[[[lidar_distance]]]]
   

   [[year_images]]
   
      [[[year_lidarsnowfall]]]
         yscale = 0.0, None, 0.5
         plot_type = bar
         [[[[lidar_snowfall]]]]
      
      [[[year_lidarsnowdepth]]]
         yscale = 0.0, None, 0.5
         plot_type = bar
         [[[[lidar_snowdepth]]]]
      
      [[[year_lidardistance]]]
         yscale = None, None, 1.0
         plot_type = bar
         [[[[lidar_distance]]]]
   

9. Restart WeeWx sudo service weewx restart and data should begin to populate.