I finally completed writing code for a Marquee Display and since I used the morning of 14th August to write this code, the least I could do was to celebrate Pakistan’s Independence Day as the first message and test for my code.
The code has DEFINE(s) for Display Length, Message Length, Speed Control and a Full-Size-AlphaNumeric-Font. Putting in a new message or updating via UART is also supported as the message array is built at run-time.
Complete code was written by me and this time, I didn’t Google once to see how others have done similar work. Now I think I will do some searching and compare my code with others.
Using AVR Atmega8, with an empty MAIN LOOP as everytihng is handles by a TIMER. The AVR sends commands via SPI to 2 Shift Registers (74HC595) which are connected in a way to overflow the data to the last register.
Here’s the Schematic; the resistors etc are not shown; I will probably put up a more detailed version sometime soon.
The 3 wires going up and out of the schematic are the SPI wires goign to AVR.
I have not uploaded the Project Files yet, as I am still tinkering with the code, but if you want to get the AVR Studio Project Files and the Circuit/Simulation, just say so in the comments…