Document FTDI_PINOUT and FTDI_INTERFACE options

Author: lorf

README.md

@@ -84,6 +84,8 @@ while CSR chips require 3.3V or 1.8V I/O level. You may supply appropriate
 VCCIO to FTDI chip or use logic level converter if levels don't match. See
 description of VCCIO pin in FTDI chip datasheet for details.
 
+This is a default pinout:
+
 | Signal | FT232RL pin | FTDI pin name | FTDI GPIO bit | CSR pin  |
 |--------|-------------|---------------|---------------|----------|
 | CS#    | 2           | DTR#          | D4            | SPI_CS#  |
@@ -105,6 +107,8 @@ LED connections are optional. Wire LED cathodes through the current limiting
 resistors (330 Ohm works fine) to the appropriate FTDI
 pins. Wire LED anodes to FTDI 3V3 pin.
 
+Other pinouts can be specified with `FTDI_PINOUT` [Option](#options).
+
 Don't power BlueCore chip from FT232R internal 3.3V regulator! It's current
 draw may exceed FT232R 50mA limit, which may cause communication errors.
 
@@ -228,6 +232,22 @@ variables or using the -TRANS option to most CSR commandline apps.
 * `FTDI_LOG_FILE` - specify log file name. Can be set to `stdout` to log to
   standard output, or to `stderr` to log to standard error stream. Default:
   `stderr`.
+* `FTDI_INTERFACE` (since version 0.5.1) - specify interface on multi-interface
+  chips (FT2232, FT4232). Default: `A`.
+* `FTDI_PINOUT` (since version 0.5.1) - specify a pinout. Available pinouts:
+  * `default` - default pinout as described in
+    [Using FT232RL breakout board as a programmer]
+    (#using-ft232rl-breakout-board-as-a-programmer).
+  * `noleds` - this is the same as `default` but without LEDs.
+  * `hwspi` - pinout for use with MPSSE chips (FT2232, FT4232, FT232H), uses
+    the same pins as hardware SPI. Note that hardware SPI capability is not
+    used, just the same pinout is used for convenience. This pinout can be used
+    with adapters like [TIAO TUMPA]
+    (http://www.tiaowiki.com/w/TIAO_USB_Multi_Protocol_Adapter_User's_Manual).
+    The pinout is as follows: `CS` - `DBUS3`, `CLK` - `DBUS0`, `MOSI` -
+    `DBUS1`, `MISO` - `DBUS2`.
+  * `hwspi+leds` - this is the same as `hwspi` but adds read and write LEDs on
+    `DBUS4` and `DBUS5` pins respectively.
 
 For other options see [misc/transport-options.md](misc/transport-options.md).