Mobile Lap Timer for Track and Field Events








I happened to have an old AMS (Betabrite) LED marquee sitting around, so I decided to configure it as a large readout. The sign is controlled via rs232 with an Arduino RBBB. A Betabrite sign can read/write text, dots, strings, or configuration commands. A text message is the easiest to configure and is a good starting point (see resources below for examples). However, the sign will blink every time a text message updates. The sign blink isnt a problem for things that update infrequently, but it becomes annoying for a clock (that updates once a second).


Strings are designed to be rapidly updated, but are more challenging to implement.

Here is the basic sequence for using strings:

1) A space in sign memory is allocated for a string.

2) A text message is saved in memory. This message will call the string as a variable. (e.g. Text:The Temperature is XX degrees Celsius, String: XX = 12)

3) A string is sent to the sign, every time display data updates.


See my string example code for an implementation for Arduino.


I came across a few good resources that covered interfacing with Betabrite signs:

Good resource for basic hardware configuration (cable fabrication and test code)


Someones test code (good for verifying cable integrity)



Helpful discussion of Betabrite communications protocol (useful example code)


Another discussion of Programming LED signs


Here is a copy of the Alpha Sign Communication Protocol. The manual is a bit cryptic at first, but there are a few good code examples.

Alpha Sign Communication Protocol (PN 97088061).pdf