Scrolling Color LED Sign
Click here for a demo of the sign running BART & Muni departures.
The Prolite PL-M2014R is one of those signs in delis and head shops. It's pretty cool. It can be programmed over a RS-232 serial port and a PC running Linux. The serial protocol is documented online and printed on paper in the space.
There's a more in-depth tutorial from Linux Journal. There is a Dell Latitude D630 in the space that has a physical RS-232 port in the back and can boot from a Knoppix CD-R. There's also a decent tutorial on the wiring from Instructables.
Here's how to program the Prolite from a Linux PC! It's a little weird.
You need an RS232 compatible serial port with the pins connected like so
If you are using a straight-through cable, connect the green wire to pin 3 of the DB9. The red wire will go to pin 2, and the black wire will go to pin 5.
If you are using a cross-over cable, then you will be connecting green to pin 2, red to pin 3, and yellow to pin 5.
Serial terminal connection. Use the minicom utility or socat. Your terminal should be /dev/ttyS0
modem baud: 300 8N1 Hardware flow control: OFF send data with printf "<ID01><PA>\r\n" > /dev/ttyS0
To play back a program, the letter to reference the program is off by one compared to the letter to write a program. So to program A type <PA> but to playback A type <PRB>. This is caused by the built-in demonstration, which is bound to a silent memory location named nothing, though addressed as location A. If you issue the command <PRA> the sign will perform the demonstration.
To debug connectivity, you can cat /dev/ttyS0 . When you send a command with printf, it should echo <ID01> back to the terminal.
- Write a www to this sign interface.
- Write a voice transcription to this sign interface.