Alpha 220 LED Sign

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Revision as of 15:59, 10 August 2007 by Ramuk (Talk | contribs) (MODE TAG and COLORTAG)

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You can find one of these signs for less than $100.
220 Full Matrix, (Case 37.7" x 3.8" x 2.9 ") Tricolor[1]

Install a Serial Port Interface

I this case a KuroBoxPro was used however any Linkstation could be used by accessing the serial port interface.

First you are going to have to install a serial port interface. There are two physical serial ports on the KuroBox. One serial port on the bottom[2] which is the same as the port on the Linkstation Pro and one on the daughterboard accessible from the front. Both are addressed as /dev/ttyS0. Consider soldering in a pinheader rather than the pressure connector used in the method described in the LSPRO method.

The cheapest TTL/RS232 converter found was from futurelec, however the order is shipped from thailand so it takes 2-3 weeks to get it.

ET-MINI RS232 3V.jpg

The sign uses a 6 conductor RJ-12 Jack. A snap in RJ-12 jack is used to interface the sign to the serial port converter



The serial port board/connector are then enclosed in a 2 port surface mount housing



Interface Sign to Serial Port Interface

A standard 6 wire telephone cable meant for a two line phone is used (a 4 wire one will not work) Plug one end into the sign, and one end into the Quick port RJ-12 Jack. Wire the jack into the serial port board as such[3]

  • Pin 4 of the RJ12 to RS-232 RX.
  • Pin 3 of the RJ12 to RS-232 TX
  • Pin 6 of the RJ12 to RS-232 GND

Setup the serial port

Adjust the serial port settings, below is a script to do this. This information comes from a FAQ on using the Alpha sign with Linux[4].


# /usr/local/bin/setledsign

rm /dev/alpha
ln -s /dev/ttyS0 /dev/alpha
chmod a+rw /dev/alpha
stty 9600 -opost -ocrnl -onlcr cs7 parenb -parodd < /dev/alpha

Wake up the sign and display something on it

# Script will display the contents of /tmp/textfile to the ALPHA 220C LED
# Display
# Usage

# Get the attention of the sign
print "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";

# Tell the sign to print the message
$message = `cat /tmp/textfile` ;

print "\001" . "Z" . "00" . "\002" . "AA" . "\x1B" . " $ARGV[0]" . "\x1C" . "$ARGV[1]" . $message . "\004";

Alpha Sign Syntax

"\001" "Z" "00" "\002" "AA" "\x1B" "t" "\x1C" "1" Hello World "\004"
Value Meaning Code Type
\001 SOH Start of Header
Z Direct at all Signs Type Code
00 All Signs Should Listen Sign Address
\002 Start of Text Character Start Type
A Text File Write File Type
A A File Label
\x1B ESC Start of Mode Field
t compressed text MODE TAG (see below)
\x1C color control code Control Code
1 red COLORTAG (see below)
Hello World Text Message
\004 EOT End of Transmission


The key parts of this are the MODE TAG and COLORTAG, there is full documentation available for this[5][6]but here are the pertinent parts.

a Regular smooth scroll, right to left
b Appear. Centers as much of message on screen, waits, and displays rest of message in similar manner
c Appear with flashing.
d Auto. Randomly picks an effect for each part of the message, as opposed to the message as a whole.
e Scroll up.
f Scroll down from top.
g Jerky scroll from right to left.
h Jerky scroll from left to right.
i Wipe up from bottom, covering text.
j Wipe down from top, covering text.
k Wipe over from right to left, character by character, not by pixels.
l Wipe over from left to right, character by character.
m Scroll up. Same as 'e'?
n This is doing something weird based on message itself. Will have to investigate.
o Auto/Random (same as 'd'?)
p --> CENTER <-- Text appears at sides and squishes content in.
q <-- CENTER --> Text splits in center and pushed content out.
r --> COVER <-- New text covers old out to in.
s <-- UNCOVER --> New text uncovers in to out.
t Compressed text! Using this mode the sign tricks your eyes into seeing more characters than it is capable of physically producing. Scrolls right to left.
u Fast Appear.
v Medium Appear.
w Maybe medium-slow appear.
x Same as 'p'?
y Same as 'q'?
z Same as 'r'?
@ The sign went blank.
1 Red
2 Green
3 Amber
4 Dim red
5 Dim green
6 Brown
7 Orange
8 Yellow
9 Rainbow 1
A Rainbow 2
B Color mix
C Autocolor

Stock Ticker

The sign can be used for a number of purposes (to display weather forecasts from an RSS feed, to display news feeds as a news ticker) As a proof of concept the following script uses the sign to display a stock ticker that gets it's data from yahoo. It then colors the prices green if they are positive/up and red if they are negative/down for the day.

First install perl and make

apt-get install perl make

Then install the quote package [7]

tar -xvzf quote-0.05.tar.gz
cd quote-0.05
./make install

install curl and lynx so that they can be used later to get content from the web.

apt-get install curl lynx

Lastly here is a shell script to display the ticker


# /usr/local/bin/leddisplay
# Stock ticker symbols

stocks="  ^DJI ^IXIC ^GSPC "

        quote $stocks | cut -d"(" -f1 |sed 's/^/\x1C9 \x7F \x1C3 /' | sed '/ -/s/:/\x1C1/g' | sed '/ +/s/:/\x1C2/g' > /tmp/textfile
        $PTE/ t A  > /dev/alpha


  1. 220 brochure (Pdf)
  2. Add a Serial port to the ARM9 Linkstation
  3. Building a Data Cable for Alpha LED Scrolling Signs
  4. Using the Alpha 215C with Linux
  5. Alpha Sign Communications Protocol (pn 9708-8061)
  6. Alpha® Sign Communications Protocol Revision F
  7. quote -- command-line stock quote display