OrnaMatrix

"OrnaMatrix" is a further development of Ornament. This project uses a 5x7 pixels LED dot matrix display to show a text ticker in landscape format (5 pixels high, 7 pixels wide). To use the little space on the display efficiently, a self-made proportional font containing all ASCII characters is being used. Like with Ornament, there are no resistors for the LEDs to keep it as simple as possible. Unfortunately, this leads to problems as the different rows draw different currents depending on the number of LEDs switched on. The result is that in rows with many activated LEDs are a little darker than the others. To reduce this effect, two paralleled outputs are being used for each row. Thus, no port pins are wasted.</p

Assembly

The text and the speed can be changed using a simple RS232 cable with no additional components, just connect ground and TxD to the AVR. As opposed to the Ornament, there should be no issues with different ports here as the LEDs are disabled while transferring data. Some ports need a hardware handshaking simulation, you can achieve this by connecting pins 1, 4 and 6 as well as 7 and 8 together (pin numbers given for a 9-pin connector).

I don't know the exact type of the dot matrix display as it was given to me with 2 (nearly) broken off pins. It says "CSM-57211E" on the side.

Programming

The text is being programmed by connecting the serial cable before applying power to the controller. If the ticker starts anyway, it's probable that the contacts are interchanged. If the connection succeeds, you can send the following commands with 1200 Baud (8 data bits, 1 stop bit):

• set text: <text (max. 111 characters)> <ENTER>
• set ticker speed (in 1/30 seconds): <ESC> D <3 digit value> <ENTER>
• change to ticker: <ESC> <ESC> <ENTER> or <ESC> Q <ENTER> or <CTRL-D> (or just remove the connection to the PC and disconnect the battery for a short while)

<ENTER> means either <CR> or <LF> or even both (as an empty string will be ignored), <CTRL-D> can also be used. Instead of the uppercase letters, lowercase is also possible. The 3 digit value must be 3 digits long (use 010 instead of 10) and must be in the range of 001 to 255 (not checked by the software!). Other commands than the ones described above will be ignored. Remember to add a few spaces to the end of the text to get a short pause before the text starts over!

Schematic/Software

• AVR-Firmware v0.8 (Assemblercode und Hexfile)
• AVR-Firmware v0.8.1 (für Tiny2313 und Tiny24) (Assemblercode und Hexfile) mit korrigiertem Zeichensatz

• Schematic (the pin numbers of the display in the schematic are not the same as the ones of the big display I used!)
• Schematic for the mini version with Tiny24 controller which can be soldered directly to the display. Unfortunately, the row connected to the Reset pin is a little darker than the others.
• AVR Firmware v0.8 (assembly code and hexfile)
• AVR-Firmware v0.8.1 (for Tiny2313 and Tiny24) (assembly code and hexfile) with corrected charset

Fotos

Gallery of this project and Ornament.

-- ArneRossius - 07 Jul 2007