improve readme

README.md

@@ -1,3 +1,56 @@
 # ha-noaa-space-weather-sensor
 
-MQTT sensor to send NOAA space weather data to Home Assistant.
+*MQTT sensor to send NOAA space weather data to Home Assistant.*
+
+## Install
+
+1. Create an account at <https://urs.earthdata.nasa.gov>
+2. `pip install -r requirements.txt`
+3. `sudo apt install p7zip-full`
+
+### Google Chrome
+
+If you don't have Google Chrome installed (used to log into the NASA site), here's how to install it.
+
+```shell
+wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
+apt install ./google-chrome-stable_current_amd64.deb
+```
+
+## Run
+
+The lat/lon range is used to pick the region of the planet for generating statistics, for example your home state. To
+
+```shell
+LAT_RANGE_MIN=<lower range for lat bounding box> \
+LAT_RANGE_MAX=<upper range for lat bounding box> \
+LON_RANGE_MIN=<lower range for lon bounding box> \
+LON_RANGE_MAX=<upper range for lon bounding box> \
+CDDIS_USERNAME=<username> CDDIS_PASSWORD=<password> \
+MQTT_BROKER_HOST="<Home Assistant IP>" MQTT_BROKER_PORT=1883 MQTT_USERNAME="user" MQTT_PASSWORD="<password>" \
+python3 main.py
+```
+
+An example systemd service file is provided.
+
+### Home Assistant MQTT Config
+
+```yaml
+- state_topic: "space-weather/vtec"
+  name: "VTEC"
+  unit_of_measurement: "(10^16 el) / m^2"
+  state_class: measurement
+  unique_id: space_weather_vtec
+```
+
+## Data
+
+### VTEC
+
+<https://www.spaceweather.gov/products/us-total-electron-content>
+
+Unit: `(10^16 el) / m^2`
+
+VTEC, or Vertical TEC, is a specific type of TEC measurement that is taken along a path extending
+vertically from the Earth's surface to the edge of the atmosphere. So essentially, VTEC is a subset of TEC, with the
+difference lying in the specific path along which the measurement is taken.

service/vtec.service

@@ -6,7 +6,7 @@ After=network.target
 Type=simple
 User=homeassistant
 EnvironmentFile=/etc/secrets/space-weather
-ExecStart=/srv/space-weather/venv/bin/python /srv/space-weather/ha-noaa-space-weather-sensor/main.py
+ExecStart=/srv/space-weather/ha-noaa-space-weather-sensor/venv/bin/python /srv/space-weather/ha-noaa-space-weather-sensor/main.py
 Restart=on-failure
 RestartSec=5s