About: A Narrow Casting solution with Master-sender and slaves-receivers used as Public Displays or Public Actuators.
 Start date:  24/08/2011
 Last changed:  16/04/2013



  1. Introduction

  2. CastDuino is a Narrow Casting Solution. It's capable of managing multiple slaves through one master, in order to show text, tweets from people, search for hashtags, show current time and execute tasks.

    See it as a public display or ticker, showing you time based programmed massages, a clock and it can do things like sounding an alarm.

    But I can think of a lot more uses. It could be used in schools for daily announcements on screen, or repeating announcements over the intercom (sound). One could use TFT,LED or LCD screens next to the classroom doors to show the next class info. Or use it in shops in order to advertise messages, or make it do things like unlocking doors at certain moments... Well if you have a great idea, let me know.

  3. Features
    • uses 1 CastDuino Master for centralized management.
    • add up to 8 different CastDuino slaves to create your own message ticker displays.
    • add up to 16 different time based jobs to trigger 8 different actions.
    • show up to 8 different time based messages (80 characters).
    • or show up to 8 different time based tweets or hashtags (140 characters).
    • Set up and show the correct time on each ticker display (using NTP).
    • Divide slaves into 8 different groups.
    • power failure proof (using EEPROM for storage)
    • 1 Master can handle 8 slaves (more masters = more slaves)

  4. History

Back in 2009, I was asked in our company to get some Real Time Clocks with a big digital Display and they all had to display the exact same time. When I started looking for those (with radio connections for time updates), I found out it would be quit expensive.Then the next question came. Isn't there something that can display short messages as well, and while you're at it, we need something that makes a sound at lunch breaks.

So I contacted @delegatevoid and we made Lumay, a casting solution running in Adobe Air. It showed a digital clock and a txt message on a computer running Ubuntu. I hang up some 19" LCD screens, used a VGA-splitter and connected all my screen through a VGA-to-CAT5 converter. This way, I only had 1 computer showing the same thing on multiple screens.

Now the day has come, they want different messages on different screens, different sounds on different locations and so on. Our Lumay solution would do, but becomes to expensive this way. Mind you, 19" or 21" LCD screens are still the cheapest solution (edit: Dot Matrix are cheaper), but multiple computers, VGA-splitters and VGA-to-CAT5 are not that cheap any more.

That is why I started CASTDUINO. A narrow Casting Solution based on Arduino that can send text and action messages to other Arduino's showing and doing the stuff you decide it to show and do.

CastDuino Arduino's



Master CastDuino Homepage
Master CastDuino broadcast page
Master CastDuino create slaves page
Master CastDuino Create Jobs page
Slave CastDuino Homepage
Slave CastDuino Jobs page
Slave CastDuino Setup Page



If you would like to comment, you can do so on the arduino forum in this post:,71543.0.html
more on UDPSendReceiveString:
more on UdpNtpClient:
more on EEPROM:
more on PROGMEM:
more on TIME: