Wednesday, 8 November 2017


My title will no doubt remind regular readers of 2013's Weather Guy, a weather app which completely maxed out an ATMega328. Well it's had a technology refresh replacing Ethernet with Wifi, XML with JSON and AVR with ESP. A surprising amount of display code survived the upgrade and can be found on GitHub (along with Eagle files and Gerbers).

The hardware has also been simplified and now comprises merely:
The Wemos has been mounted on the underside of the board as can be seen above, because I soldered its pin headers on the wrong side; however this suggests to rotate the display by 180 degrees, making the build more compact.

The software is built on the following fine components:
Perhaps the most interesting aspect of this build is its configuration:
  • Stored in JSON format in the onboard flash filesystem
  • An index.html is served to a browser which loads the configuration file and initialises form input items (via Transparency)
  • Submission of the configuration form transmits the form values in JSON format to the server where it is stored back in the filesystem
  • The index page also supports firmware upgrade
This pattern, where the client assembles a UI for the user out of pieces obtained from the server is finally becoming prevalent in the wider web, but nowhere is it more useful than here where the client has maybe 200x the power of the serving microcontroller.

The Weather Underground API provides current conditions, a 5-day forecast and astronomical information. Two of these can be seen below.

Sunrise and Moon Phase

Current Weather Conditions

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