Small test of fast communication between STM32F4 and ICE40 using the STM32 FSMC.

Pinout for the FSMC (this for plugged into the J3 slot):

  func  STM32  ICE40
  A0    PF0    R4
  A1    PF1    R3
  D0	PD14   N10
  D1	PD15   M11
  D2	PD0    T16
  NE2	PG9    N12
  NOE	PD4    T13
  NWE	PD5    P13

The external clock for the ICE40 is on J3. A test pin PB11 on the
STM32F4 is connected to R16 on the ICE40. A serial Tx out from STM32
can be connected from PB10 on the STM32F4 board to T15 on the ICE40
(will be proxied to the FTDI on the ICE40 breakout board).