Jonas Horberg [jhorberg@sauer-danfoss.com]

https://lists.berlios.de/pipermail/openocd-development/2009-August/009939.html

1. It can only be built with the FTD2XX driver. libftdi supports FT2232H/FT4232H 
since version 0.16 

2. A speed value of 0 is used as a RTCK request indicator. This clashes with the 
valid clock division value 0 that provide the highest fixed clock frequency. 

3. The ft2232_speed_div function return the maximum selectable frequency (30MHz) 
when RTCK is activated. It should return 0. 

4. The ft2232_khz function return ERROR_OK when RTCK is requested even for 
devices lacking RTCK support. It should return ERROR_FAIL so the upper driver layers 
can detect this and try to fallback to a fixed frequency. 

5. FT2232H/FT4232H have a backward compatibility function that divide the clock 
by 5 to get the same frequency range as FT2232D. There is no code that disable 
this functionality. I can not find anything about if this is enabled or disabled by default. 
I think it is safest to actively disable it. 


git-svn-id: svn://svn.berlios.de/openocd/trunk@2591 b42882b7-edfa-0310-969c-e2dbd0fdcd60

1 files changed, 12 insertions, 11 deletions

diff --git a/README b/README
index e3b49a9..d95d689 100644
--- a/README
+++ b/README
@@ -125,7 +125,7 @@ Building OpenOCD
 The INSTALL file contains generic instructions for running 'configure'
 and compiling the OpenOCD source code.  That file is provided by default
 for all GNU automake packages.  If you are not familiar with the GNU
-autotools, then you should read those instructions first.  
+autotools, then you should read those instructions first.
 
 The remainder of this document tries to provide some instructions for
 those looking for a quick-install.
@@ -163,7 +163,7 @@ To build OpenOCD (on both Linux and Cygwin), use the following sequence
 of commands:
 
    ./configure [with some options listed in the next section]
-   make 
+   make
    make install
 
 The 'configure' step generates the Makefiles required to build OpenOCD,
@@ -180,7 +180,7 @@ the 'configure' script.  For example, you can configure OpenOCD to
 cross-compile on a x86 Linux host to run on Windows (MinGW32), you could
 use the following configuration options:
 
-  ./configure --build=i686-pc-linux-gnu --host=i586-mingw32msvc ... 
+  ./configure --build=i686-pc-linux-gnu --host=i586-mingw32msvc ...
 
 Likewise, the following options allow OpenOCD to be cross-compiled for
 an ARM target on the same x86 host:
@@ -215,9 +215,10 @@ options may be available there:
                           FTD2XX
   --enable-ft2232_ftd2xx  Enable building support for FT2232 based devices
                           using the FTD2XX driver from ftdichip.com
-  --enable-ftd2xx-highspeed
+  --enable-ft2232-highspeed
                           Enable building support for FT2232H and
-                          FT4232H-based devices (requires >=libftd2xx-0.4.16)
+                          FT4232H-based devices (requires >=libftd2xx-0.4.16
+                          or >=libftdi-0.16)
 
   --enable-gw16012        Enable building support for the Gateworks GW16012
                           JTAG Programmer
@@ -301,12 +302,12 @@ have to use both the --enable-parport AND the --enable-parport-giveio
 option if you want to use giveio instead of ioperm parallel port access
 method.
 
-FT2232C Based USB Dongles 
+FT2232C Based USB Dongles
 -------------------------
 
 There are 2 methods of using the FTD2232, either (1) using the
 FTDICHIP.COM closed source driver, or (2) the open (and free) driver
-libftdi. 
+libftdi.
 
 Using LIBFTDI
 -------------
@@ -320,7 +321,7 @@ installed.  To use the newer FT2232H chips, supporting RTCK and USB high
 speed (480 Mbps), you need libftdi version 0.16 or newer.  Many Linux
 distributions provide suitable packages for these libraries.
 
-For Windows, libftdi is supported with versions 0.14 and later.  
+For Windows, libftdi is supported with versions 0.14 and later.
 
 With these prerequisites met, configure the libftdi solution like this:
 
@@ -340,7 +341,7 @@ copies for personal use.
 The FTDICHIP drivers come as either a (win32) ZIP file, or a (Linux)
 TAR.GZ file. You must unpack them ``some where'' convient. As of this
 writing FTDICHIP does not supply means to install these files "in an
-appropriate place."  
+appropriate place."
 
 If your distribution does not package these, there are several
 './configure' options to solve this problem:
@@ -361,7 +362,7 @@ Windows or Linux FTD2xx drivers from the following location:
 Remember, this library is binary-only, while OpenOCD is licenced
 according to GNU GPLv2 without any exceptions.  That means that
 _distributing_ copies of OpenOCD built with the FTDI code would violate
-the OpenOCD licensing terms.  
+the OpenOCD licensing terms.
 
 Linux Notes
 ***********
@@ -404,7 +405,7 @@ Tips For Building From The Subversion Repository
 ************************************************
 
 Building OpenOCD from a repository requires a recent version of the GNU
-autotools (autoconf >= 2.59 and automake >= 1.9).  
+autotools (autoconf >= 2.59 and automake >= 1.9).
 
 1) Run './bootstrap' to create the 'configure' script and prepare
    the build process for your host system.