Ledslie

Projects
Participants	Chotee, Thijs
Skills	electronics, microcontrollers, linux, mqtt, webservices
Status	Active
Niche	Electronics
Purpose	Infrastructure

Interface to display information

• It is a Grayscale display of 144x24 pixels that displays information.
• It lives at http://ledslie.ti/ and is accessible at the space via a website and mqtt.

Interfaces

• At http://ledslie.ti/ you to submit content, such as animated GIFs, from your browser.
• You can publish content by posting content to the web-service.
• You can publish content directly to the mqtt broker that lives on ledslie.ti:1883.

Content ideas (in no specific order)

• Spacealert with message.
• IRC integration via shardik: .display [message]
• Indicio audio: What are we listening to?
• Wifi SSIDs being broadcast
• Next and last tram / metro / nightbuses -- Eg: http://v0.ovapi.nl/line/GVB_2_1
• (Done) Incoming rain alerts (https://www.buienradar.nl/overbuienradar/gratis-weerdata, https://br-gpsgadget-new.azurewebsites.net/data/raintext/?lat=52.35&lon=4.83)
• Clocks + Midnights ("Midnight in «City»")
• Drama stats
• API/Interface for countdowns.
  • (Done) Next TI events
  • TI ALVs
  • Next interesting rocket launch (SpaceX, Soyuz, etc...)
  • Space dates / launches
  • ISS flyovers
  • Zonsopkomst en -ondergang tijden
  • Maan standen. volle maan, nieuwe, etc.
  • http://www.apiblog.nl/
• External content
  • Security.nl
  • Theregister.co.uk
  • hackernews.
  • Radio Yerevan Jokes: https://duckduckgo.com/Radio_Yerevan_jokes?iax=1&ia=about
  • Jargon file
  • Btc/Eth values

How it works

Wifi --RF> Getchip --USB2> Teensy --[data,clock,latch]> Led-pannel

The led-panel takes 20V DC as input. At full output it's pulling about 4A, or about 80W. There's a small switcher-board that supplies the 5v the the getchip and Teensy from those 20V.

The Teensy drive code is here: https://github.com/techinc/ledmatrix/tree/master/ledmatrix144x24

The Ledslie code can be found here: https://github.com/techinc/ledslie

Possible Hardware expansions

• Add another panel by adding a USB2 hub, and modding another of the led panels with the teensy taking over the driving logic.

FAQ

• Q: What's that noise? A: The panel is being driven at rates way beyond the original design and we're well in the audible frequencies with the refresh-rates and some components are merrily humming along.
• Q: Why are some points brighter then others? A: Turns out that LEDs do wear. In their previous life some LEDs were on for years, while others were always off. There's plans to compensate for this in software.