Now that the design review is complete, I am updating the PCB layout.

I started by going into CvPCB to check and fix any components. I feel that the pad sizes are too large with the Handsoldering footprints.  I changed all 1206 Handsoldering footprints to 1206 standard  footprints. The 1×12 connector hasn’t been assigned yet, I chose a 0.100″ pin header footprint which I will leave empty. The Socket Strip 1×12 fit my needs.

While doing some research, I found a chip to replace the level shifter chips I was using.  The FXMA108 chip by Fairchild Semi does all 8 bits with automatic direction changing.  It’s capable of up to 80 Mb/s.  It allows me to simplify my design and remove the shift register.  Each buffer automatically shifts direction based on how its pins are being driven.  I removed the four level shifter chips and replaced them with this one chip. I had to create the chip in my library.

While moving parts around the layout, PCBnew shut down unexpectedly and I lost about 2 hours worth of work. There are so many changes to this layout that I decided to remove all of the traces and start new.  Under the edit menu is Global Deletions, I selected tracks and hit OK.

I moved the microUSB connector to hang off of the edge of the PCB and changed the slotted holes to round with the longest dimension used for the diameter of the circle. I moved the component values outside of the board boundary which helped remove some clutter from the board.

I started laying out the traces around the level shifter first because that section is straight forward.  Ikepth the schematic open so i could make quick changes on the schematic to simplify the layout. With each change I madeon the schematic, I would generate a new netlist and then read it into PCBnew. I made many component placement adjustments while routing the traces. I finished by doing a fill of the ground plane on the bottum side of the board.  This made a couple of unconnected nets stand out so I fixed them.