  An inexpensive, easily programmed microcontroller is demonstrated for the
fast frequency stabilization of an infrared fiber laser. The microcontroller
manages all digitalization and processing, with external circuitry only
providing buffering, amplification and overvoltage protection. Several
convenient features are included to recover from common failure modes of a
laser lock system, and a final Nyquist frequency of 200 kHz is obtained,
corresponding to a usable bandwidth of 40-60 kHz.
