Schematic and Improvements

A project log for Persistence Of Vision LED Matrix MKII

It's Redesign Time

Matthew James BellafaireMatthew James Bellafaire 04/27/2019 at 18:250 Comments

the previous matrix display had an effective resolution of 10x10 LEDs, this time around I want to increase that number. Ideally this project would not use the shift registers that plagued the performance of the previous iteration. 

For this version I've chosen the ATMEGA2560 to control the LED's, this way the IO can control the LED's directly, however that came with some constraints and some easy improvements. The MK.II persistence of vision matrix display will utilize an 16x16 LED matrix to create its images. the ATMEGA2560 is perfect for this application (although pricey), since 6 output ports can be dedicated to the high side (RGB) of the matrix and 2 output ports can be dedicated to the low side of the matrix. The overall result of this is that the final matrix will operate much more quickly. With all that said lets go through the finished schematics for the project. 

kiCad doesn't allow for flat schematics, which is somewhat of a pain, so we'll have to take a look at the this schematic as a kind of block diagram. The port assignments are as follows 





the ATmega2560 cannot drive the LED's directly, therefore this project will utilize "a few" transistors to drive the matrix display, the two larger blocks to the right are those transistor arrays. 

On the left towards the top we have the battery management and power system: 

and along with that all the circuitry for powering the matrix directly

This is a rather big circuit, I've already begun the PCB layout which'll be the subject of the next log!