Board characteristics:

- two layers, components only on front
- smallest components are 0402 and 0.5 mm pitch QFN
- one through-hole component: USB connector CON1
- the following component orientation markings are on the silk screen:
  B1: circle near pin 1
  D1: plus sign at the anode
  U1, U2: triangle at the corner between pins 1 and 32
  

Design files:

atusb-front.png		Illustration of the PCB's front side (with silk screen)
atusb-bom.csv		Bill of materials
atusb-pos.csv		Automatic insertion file (front only)
atusb-footprints.pdf	Footprint reference drawings

The PCB design files (Gerbers, etc.) are in a separate archive, atusb-pcb-*


Interpretation of files:

- for all coordinates, the origin is the lower left corner of the board
- coordinates in atusb-pos.csv are in inches
- rotation in atusb-pos.csv is in degrees, counter-clockwise
- in the footprint reference drawings, footprints are shown in the 0 degree
  orientation and with their center at the crosshairs
