XOrduino

Notes on XOrduino v4 boards:

- avoid tab on usb connector, move to body
- N/C jumpers turned out N/O (scratch sensor board)

.- merge 5V and +5V nets

- C5/C7 too close together (and too close to C9) & need polarity marks
- C11/C13 needs polarity mark (or to be unpolarized)
- flip RN3?
- audio jack footprints are wrong.  and drill holes overlap for top&bottom
- just use tip and sleeve(gnd) on audio jack (leave ring(s) disconnected)
  use 1/8" instead of 3/32"?
  digikey CP1-3523N-ND $0.39480 qty 100 (stereo, no switch)
- right angle pot is right but don't need strain relief holes, need knob (shorter handle?)

.- mini USB jack silkscreen on wrong side .- mini USB just a tiny bit too close to pcb plug

- mounting hole clearances too small:
   
- add front nose skid (near where audio jack currently sits?)
- potentiometer footprint 
- add light sensors and/or bumper switches somehow
  light sensors pointed at the wheels?
- add labels to new arduino 1.0 pins (SCL/SDA above AREF)
- add breakoff tabs to thicken USB plug (by reset pin, two deep)
- solder spot under AVR is unnecessary
- male header strip should be female for arduino headers
  1x S7004-ND (6 pin)
  2x S4008-ND (non-stock) or S7006-ND (8 pin)
  1x S7043-ND (10 pin) or S7008-ND (should be cheaper, but isn't)
- ISP header needs pin 1 indication, label.
- Yellow LEDs don't have a flat side!
- add LED polarity silkscreen
- remove solder mask on solder jumper center
- replace 2x7 shorting header w/ 1x7 signal header and array of
  shorting jumpers

NOTE THAT ATmega32u4 should be placed upside down. (rotate it?)

TESTED: xorduino can be programmed w/ nothing mounted but the chip and the ISP header.