This article describes how to connect FreeCalypso DUART28 adapter to an FCDEV3B
target board, both the main connection of dual UART and optional boot control
connections.

Main connection: dual UART
==========================

The main connection of two UARTs is made with a 10-wire ribbon cable.  You
should have received the correct cable from Falconia Partners LLC together with
your FCDEV3B+DUART28 board kit - it is a rainbow-colored 10-wire ribbon cable
with two different end terminations: one end is terminated with a blue or grey
IDC connector, the other end is terminated with a black connector into which
individual wires are inserted from the top.  The blue or grey connector goes to
the DUART28, the black connector goes to the FCDEV3B.

The blue or grey connector going to the DUART28 board is keyed such that it can
be inserted in only one orientation, hence that one is expected to be always
correct.  The black connector goes to the middle of the three headers on
FCDEV3B (J301), and in this case you are responsible for ensuring the correct
orientation.  If you are using the official DUART28 to FCDEV3B cable from
Falconia Partners LLC, then the side with brown and red wires needs to be
facing toward JTAG and power input connectors.

Optional boot control provision
===============================

If you wish to connect the optional boot control signals, connect two
individual jumper wires as follows:

* For PWON control, connect DUART28 CTL1 to the top pin of 2-pin header JP1 on
  FCDEV3B, namely the pin that is closer to the adjacent PWON button.  (The
  other pin on JP1 is ground.)

* For RESET control, connect DUART28 CTL2 to JTAG connector J310 pin 2 on
  FCDEV3B, which is the XDS_RESET signal.  Naturally one cannot connect both
  DUART28 CTL2 and JTAG at the same time.

* Ground connection between the two boards will normally be provided by the
  main dual UART cable.

If you are going to connect these boot control signals, you MUST reprogram the
EEPROM on your DUART28 board to the DUART28C configuration and apply the
necessary DUART28C support patch to your Linux kernel ftdi_sio driver -
otherwise your hardware setup will be inoperable, with FCDEV3B getting held
down in reset whenever the second serial port is opened for regular serial
communication.