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doc: Improve ftdi driver section 

Fix typo and a sentence that sounds strange since the ft2232 driver
was removed.

Add documentation for the SWD signal usage.

Remove the text mentioning a default VID:PID which doesn't exist.

Change-Id: I27eba571f2f7c46bdb6ae623ab285595018e99d9
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/3935
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
This commit is contained in:
Andreas Fritiofson 2017-01-03 00:18:34 +01:00 committed by Paul Fertser
parent 7436f7c2c0
commit 52a396656a
1 changed files with 11 additions and 7 deletions
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18
doc/openocd.texi
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@ -2408,11 +2408,10 @@ This driver is for adapters using the MPSSE (Multi-Protocol Synchronous Serial
Engine) mode built into many FTDI chips, such as the FT2232, FT4232 and FT232H. Engine) mode built into many FTDI chips, such as the FT2232, FT4232 and FT232H.
The driver is using libusb-1.0 in asynchronous mode to talk to the FTDI device, The driver is using libusb-1.0 in asynchronous mode to talk to the FTDI device,
bypassing intermediate libraries like libftdi of D2XX. bypassing intermediate libraries like libftdi or D2XX.
A major improvement of this driver is that support for new FTDI based adapters Support for new FTDI based adapters can be added competely through
can be added competely through configuration files, without the need to patch configuration files, without the need to patch and rebuild OpenOCD.
and rebuild OpenOCD.
The driver uses a signal abstraction to enable Tcl configuration files to The driver uses a signal abstraction to enable Tcl configuration files to
define outputs for one or several FTDI GPIO. These outputs can then be define outputs for one or several FTDI GPIO. These outputs can then be
@ -2421,6 +2420,12 @@ are reserved for nTRST, nSRST and LED (for blink) so that they, if defined,
will be used for their customary purpose. Inputs can be read using the will be used for their customary purpose. Inputs can be read using the
@command{ftdi_get_signal} command. @command{ftdi_get_signal} command.
To support SWD, a signal named SWD_EN must be defined. It is set to 1 when the
SWD protocol is selected. When set, the adapter should route the SWDIO pin to
the data input. An SWDIO_OE signal, if defined, will be set to 1 or 0 as
required by the protocol, to tell the adapter to drive the data output onto
the SWDIO pin or keep the SWDIO pin Hi-Z, respectively.
Depending on the type of buffer attached to the FTDI GPIO, the outputs have to Depending on the type of buffer attached to the FTDI GPIO, the outputs have to
be controlled differently. In order to support tristateable signals such as be controlled differently. In order to support tristateable signals such as
nSRST, both a data GPIO and an output-enable GPIO can be specified for each nSRST, both a data GPIO and an output-enable GPIO can be specified for each
@ -2439,9 +2444,8 @@ These interfaces have several commands, used to configure the driver
before initializing the JTAG scan chain: before initializing the JTAG scan chain:
@deffn {Config Command} {ftdi_vid_pid} [vid pid]+ @deffn {Config Command} {ftdi_vid_pid} [vid pid]+
The vendor ID and product ID of the adapter. If not specified, the FTDI The vendor ID and product ID of the adapter. Up to eight
default values are used. [@var{vid}, @var{pid}] pairs may be given, e.g.
Currently, up to eight [@var{vid}, @var{pid}] pairs may be given, e.g.
@example @example
ftdi_vid_pid 0x0403 0xcff8 0x15ba 0x0003 ftdi_vid_pid 0x0403 0xcff8 0x15ba 0x0003
@end example @end example