An example program that tries to output CW using
the audio codec on the STM32F4DISCOVERY, using the FSM
and switches.

Connections as follows:

Blue    in  QRP_n   PC1
Violet  out LED red PC2
Grey    in  1750    PC4
White   out LED yel PC5
Black   -   GND     GND
Brown   in  RX_n    PC6
Red     in  U_n     PC8
Orange  out LED grn PC9
Green   in  D_n     PC11