Building a Julia-Powered E-Ink Dashboard: A Dev Log

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Log 02: July 13th, 2025 - Weather Imagineering

After tinkering further with OpenMeteo, I decided to take a break and determine what data I want exactly. I concluded that basically, this is the information I want from the Weather Forecast API:

Location

  • latitude=42.3751
  • longitude=-71.1056

Daily Variables Requested

  • temperature_2m_max: Daily maximum temperature at 2 meters
  • temperature_2m_min: Daily minimum temperature at 2 meters
  • sunset: Time of sunset
  • sunrise: Time of sunrise
  • wind_speed_10m_max: Maximum wind speed at 10 meters
  • wind_gusts_10m_max: Maximum wind gusts at 10 meters
  • wind_speed_10m_min: Minimum wind speed at 10 meters
  • wind_gusts_10m_min: Minimum wind gusts at 10 meters

Hourly Variables Requested

  • temperature_2m: Temperature at 2 meters
  • uv_index: UV index
  • precipitation_probability: Probability of precipitation
  • precipitation: Amount of precipitation
  • relative_humidity_2m: Relative humidity at 2 meters
  • wind_speed_10m: Wind speed at 10 meters
  • wind_direction_10m: Wind direction at 10 meters

Other Options

  • timezone=America/New_York: Output times in the Eastern Time zone (encoded as %2F)
  • forecast_days=3: Request a 3-day forecast
  • timeformat=unixtime: Timestamps in Unix time format (seconds since epoch)
  • wind_speed_unit=mph: Wind speeds in miles per hour
  • temperature_unit=fahrenheit: Temperatures in Fahrenheit
  • precipitation_unit=inch: Precipitation in inches

Curl Request Example:

curl https://api.open-meteo.com/v1/forecast?latitude=42.3751&longitude=-71.1056&daily=temperature_2m_max,temperature_2m_min,sunset,sunrise,wind_speed_10m_max,wind_gusts_10m_max,wind_speed_10m_min,wind_gusts_10m_min&hourly=temperature_2m,uv_index,precipitation_probability,precipitation,relative_humidity_2m,wind_speed_10m,wind_direction_10m&timezone=America%2FNew_York&forecast_days=3&timeformat=unixtime&wind_speed_unit=mph&temperature_unit=fahrenheit&precipitation_unit=inch

And Air Quality API:

Hourly Variables Requested

  • us_aqi: U.S. Air Quality Index (based on EPA standards)

Other Options

  • forecast_days=3: Request a 3-day forecast

Curl Request Example:

curl https://air-quality-api.open-meteo.com/v1/air-quality?latitude=52.52&longitude=13.41&hourly=us_aqi&forecast_days=3

From there, I began tinkering with how to display this data on my display. I sketched out a small draft of this here:

image
image1920×1121 108 KB

Basically, I am imagining using Makie.jl and a PolarAxis radial chart to display this information (thanks to @asinghvi17 and @sdanisch for the tips here):

You can make multiple polar axes and use PolarAxis | Makie

In my designing, I found this example to be beautiful and something I could base my work off of:

image
image1174×1006 95 KB

I also found this other example which was also hugely inspiring:

image
image5120×6810 2.17 MB

This will be a task for future TCP.

Finally, I decided to put some thoughts to code and began drafting a Jinkies.jl framework for how to “chunk” the regions of an e-ink display. As of now, I have two structs called Display and another called Component. Display holds information about the e-ink display and what components are in the display. A Component holds plotting information about what goes into the display and where.

I am imagining making Component’s more like an interface too so I can make any component that could be rendered to an image using tools like Makie, Luxor, and more.

Currently, I have made a PrettyTables.jl interface to represent an e-ink display’s pixels in a coarser granularity than pixel dimensions. Here’s how things look so far:

julia> Jinkies.set_display_grid!(100, 120)

E-Ink Display Grid
┌─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┐
│     │ 001 │ 002 │ 003 │ 004 │ 005 │ 006 │ 007 │ 008 │
├─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│  1  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │
├─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│  2  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │
├─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│  3  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │
├─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│  4  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │  ⬤  │
└─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘

And then for colors, I can do something like this to say where a part of an e-ink display already has a component:

julia> Jinkies._update_display_grid_colors!(
    [[1,1], [1,2],[2,1],[2,2]]
)

image
image682×305 7.84 KB

I like the display representation so far, but I need to mess around a bit further with the component and display interplay. Also encoding what information should be stored here and there.

And that is where we shall leave the dev log for now. Nice day of exploring, hacking, and imagineering! Onwards!

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