this may be a little ambitious since i’m new to the ardunio playground, but I have two scrolling LED marquee signs, they are 7 rows x 128 columns, for a total of 896 LEDs. The 16 panels are in groupings of 56 LEDS, 7x8.
I want to replace the main controller with an arduino and eventually have network or serial access for updating via the computer. The main controller unplugs via a 15 pin cable. I have traced every pin and determined where they go and somewhat what they are for.
I have all the part numbers for the chips inside and have been reading through datasheets for a couple of days and am starting to understand what’s for what.
In the connector I have:
-2 pins go to a sn74s138n and sn74ls00n (enable pins on 138 and -3a/3b on the s00n)
-3 pins go to the A, B, and C, selects on the same 138 chip. this chip controls the clock signal on the flip flops ( 8 for controlling ground, 1 for controlling all vcc signals to the LED’s) (2 different chips)
- the other 7 (important) pins are inputs for the flip flops
The 8 FF’s for the ground connection are part number sn74ls273n, the other one is sn74ls174n
the vcc ff connects to two sn74s138n to control the vcc transistors
the ground ff’s connect to transistors to switch to ground
the clear pins on the 273’s are connected to the s00n nand gate and the clock pin on the 174 ff
My biggest problem is understanding the clock generation and how it works with these chips. I’m not sure how to get my arduino to generate a proper clock signal (between 0 and 30 MHz). Right now I just want anything to happen, just have an LED light up would be a step in the right direction.
I am sure I have more information to provide if anybody is actually going to read this and help, but I’m not sure what else you want/need.