I proudly present my first completly self made schematic :)
Project: It will be a LED cube private, build 3 times tops, maybe presented to university as bachlor thesis. Lacking money I'll prolly solder everything on breadboards.
One computer science student programms a GUI
another cs student programms a USB-RS485 Bridge using an USBKey. I'm a electronic engineering student and provide the hardware part.
The GUI generates animations, sends it via USB to the Bridge which is acting as a RS485 master and sends the pictures slightly compressed to my PWM slaves.
The cube will be build of 1000 two color LEDs. To drive it I need 210 independant PWMs. Unable to find matching silicon I build my own ones. I'm currently using M644s which I programm in ASM.
Here is my schematic and a sketch of my 485 protocol, called cBus.
Can anyone find some major or minor flaws in my design?
Can I run into problems with my ISP connection? Did I choose PNP/NPN types in my powerstage corrrectly? Is my style of schematic drawing good? Should I put some fuses in it somewhere?
I'd like to use some 7805 types as power supply. Maximum 200 LEDs will be turned on at the same time. If each draws 20 mA I'll need like 4 A. Prolly more because of multiplex.
Is it a good idea to wire some 7805 parallel? (using protection diodes to prevent current flowing into the output) All 5 V voltage regulators I found so far supply max 1 or 2 A or cost me like 50 bucks :/
PS: labels like "0a" or "5b" are the software PWM output
PPS: after clicking on the thumbnail: a click on the picture enlarges it again