Alpha 220 LED Sign

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Revision as of 20:12, 15 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

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

First, install a serial port interface. There are two physical serial ports on the KuroBoxPro. 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 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 RXD
  • Pin 3 of the RJ12 to RS-232 TXD
  • 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].

Basically this

  1. Links /dev/ttyS0 to /dev/alpha
  2. Gives everyone read/write access to your sign (/dev/alpha)
  3. Provides a 9600,E,7,1 connection to the sign (/dev/alpha)


# /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

"\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" "\001" "Z" "00" "\002" "AA" "\x1B" "t" "\x1C" "1" Hello World "\004"
Value Meaning Code Type
\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 NULL String of Null packets to get attention of sign
\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 Message travels right to left.
b Message remains stationary.
c Message remains stationary and flashes
d Auto. Randomly picks an effect for each part of the message, as opposed to the message as a whole.
e Previous message is pushed up by a new message.
f Previous message is pushed down by a new message.
g Previous message is pushed left by a new message.
h Previous message is pushed right by a new message.
i New message is wiped over the previous message from bottom to top.
j New message is wiped over the previous message from top to bottom.
k New message is wiped over the previous message from right to left.
l New message is wiped over the previous message from left to right.
m New message line pushes the bottom line to the top line if 2-line sign.
n This is followed by a Special Specifier ASCII character which defines one of the Special Modes.
o Various Modes are called upon to display the message automatically.
p Previous message is pushed toward the center of the display by the new message.
q Previous message is pushed outward from the center by the new message.
r New message is wiped over the previous message in an inward motion.
s New message is wiped over the previous message in an outward motion.
t COMPRESSED - Message travels right to left. Characters are approximately one half their normal width. (Only available on certain sign models.)
u Message flies apart from the center (Alpha 3.0 protocol).
v Wipe in a clockwise direction (Alpha 3.0 protocol).
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


RED if they are negative/down

for the day.

Here it is in action: (clip from a cell phone so quality is somewhat poor)

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