Weewx service that pulls device health (telemetry) information from a Davis Instruments weather sensor. I made this extension for users like me who have a WeatherLink Live device, which unfortunately provides no sensor health data over the local API.
The code makes two API calls per archive period: one to the "current" v2 API, which contains values like the console battery status and firmware version, and another to the "historical" v2 API, which contains most of the sensor's health telemetry like signal strength, signal quality, solar cell voltage, and so on.
The data are stored in their own database, since most of the fields don't exist within the default weewx database. The code is patterned after the cmon driver for weewx by Matthew Hall.
Please note: most of the data is pulled from the "Historic Data" API, which requires a paid monthly subscription from Davis to use (starting at about $4/month). See here: https://weatherlink.github.io/v2-api/data-permissions
Right now, the service records the following information from the Davis WeatherLink API:
- Signal Quality (in %)
- Signal Strength (in dBm)
- Supercapacitor voltage (the rechargable battery that powers the sensor)
- Sensor Solar Cell voltage
- Good Packets Streak
- Transmitter ID
- Transmitter Battery voltage
- Rain Bucket Tips
- Solar Radiation Sensor Solar Cell voltage
- Transmitter Battery Status (OK or LOW)
- Error Packets
- AFC
- Number of re-synchronizations
- UV Sensor Solar Cell voltage
- Console Battery voltage
- Rapid Records
- Firmware Version
- Uptime
- Touchpad Wakeups
- Bootloader Version
- Local API Queries
- Data Received (in bytes)
- Davis Health Version
- Radio Version
- EspressIF Version
- Link Uptime
- Console AC Power voltage
- Data Transmitted (in bytes)
Download the repository:
wget -O davishealthapi.zip https://github.com/uajqq/weewx-davishealthapi/archive/master.zip
Install the extension:
sudo wee_extension --install davishealthapi.zip
Alternatively, you could git clone the repository and point wee_extension towards the resulting folder.
By default, the installer installs davishealthapi as a service, allowing your station to keep collecting weather information via its usual driver. It runs during every archive interval and inserts data into its own SQL database.
Once installed, you need to add your Davis WeatherLink Cloud API key, station ID, and secret. To obtain an API key and secret, go to your WeatherLink Cloud account page and look for a button marked "Generate v2 Token." Once you complete the process, enter your key and secret where indicated in weewx.conf.
Davis doesn't make it easy to make API calls, and you have to make an API call to get your station ID. To help the process along, I adapted one of Davis' example Python scripts to make an API call that shows your station ID. To use it, look for the file davis_api_tool.py in the zip file you downloaded. Save the file and run it like so:
python3 davis_api_tool.py
It will ask for your API key and secret, and then it should return a URL. Open that in a browser (don't delay, the timestamp is encoded in that URL and the Davis API will reject the call if you wait too long to make the call) and you'll get back a string of text. Your station ID will be near the beginning. Enter that number into weewx.conf and you should be good to go.
Once you enable the service/driver and get it running, you won't notice anything different. You have to manually add the appropriate graphs and tags to see the information.
If you're using the default Seasons skin, you can replace the file sensors.inc in the skins/Seasons/ folder of weewx with the example included in the download, sensors.inc.EXAMPLE. On your homepage, you should see a module called "Sensor Status" appear with the relevant data. Clicking on the header brings to you the telemetry.html page.
If you want to display graphs on the telemetry.html page, add the following to skins.conf under [[day_images]]:
[[[dayrx]]]
title = Signal Quality
data_binding = davishealthapi_binding
yscale = 0.0, 100.0, 25.0
[[[[signalQuality]]]]
[[[daysignal]]]
title = Signal Strength
data_binding = davishealthapi_binding
yscale = -90.0, -10.0, 10
[[[[rssi]]]]
[[[dayvoltSensor]]]
data_binding = davishealthapi_binding
title = Sensor voltages
[[[[supercapVolt]]]]
[[[[solarVolt]]]]
[[[[txBattery]]]]
[[[dayvoltConsole]]]
data_binding = davishealthapi_binding
[[[[consoleBattery]]]]
[[[[consolePower]]]]
Do the same under [[week_images]], [[month_images]], etc. but change [[[dayrx]]] to [[[weekrx]]], [[[monthrx]]], and so on. That tells the generator to make the graphs, but you still have to display them. For that, you can replace telemetry.html.tmpl in the skins/Seasons folder with the file from the download, telemetry.html.tmpl.EXAMPLE. Make sure you rename the example file to match the file you're trying to replace!
This should give you a result like this:
Note how the solar cell drops to zero as the sun goes down, the supercapacitor slowly discharges throughout the night, and the solar cell recharges it in the morning. It didn't get to zero so the sensor battery voltage remains untouched!
If you're using the excellent Belchertown skin to display your weather data, you can easily add graphs to graphs.conf like so:
[[voltChart]]
title = Voltages
type = spline
data_binding = davishealthapi_binding
[[[supercapVolt]]]
[[[solarVolt]]]
[[[txBattery]]]
This yields a graph that looks like this:
In all cases, note that you have to specify the database binding as davishealthapi_binding whenever you are referencing the DavisHealthAPI data!! Take a look at the example files to see how that's been done so you can adapt it for your own purposes.