Fixing delayMicroseconds() timing for 20 MHz clocks.  (Erdem U. Altinyurt)
Fixing delayMicroseconds() timing for 20 MHz clocks.  (Erdem U. Altinyurt)

http://code.google.com/p/arduino/issues/detail?id=306

rkistner/arcore,rkistner/arcore,rkistner/arcore