scrolling message display

Thread Starter


Joined Mar 10, 2009
Good day guys!!!
Im currently doing my project regarding scrolling message display comprising 7*50 arrays of LEDs. My problem is I dont have the program or code yet to display and scroll alphanumeric set of characters. My project is consist of 10 characters with Z8F082A microcontroller and zilog encore programming cable or dongle a DB9 connector for serial interface. It uses also und2981 and 74HC164 as a LED driver and shift register. The design is attached. Hope u could contribute some significant ideas. Its my great pleasure to read your ideas regarding with this project....


Thread Starter


Joined Mar 10, 2009
I wish to make a code that is written in C which displays and scrolls the message ... Hope you could help me guys....:(


Joined Feb 19, 2009
Have you tested the circuit at the point above?

It appears to be drawing 460mA (assuming 20mA/LED), the nominal current on that driver is 350mA, and the max is 500mA, with a total dissipation of just over 1 Watt max. It may work, but it's pushing the package to it's limit.

To assist in software, start with a logic diagram for what signals would be present on outputs for a vertical dotted line scrolling in from the right.

ETA: You'll need a blanking line for the display, the limit from datasheet is at 50% duty cycle, time is also needed to shift in the serial bits, so that works out well.
ULN 2981 Datasheet, Page 6
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Joined Oct 5, 2009
hey guys...
thanks for the help...
I am just starting with this project...
this information would be of great help to me...