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urjtag/jtag/doc/UrJTAG.txt

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Universal JTAG library, server and tools
========================================
Kolja Waschk (Ed.)
$Id$
/////////////////////////////////////////////////////////////////////////////
This document is formatted to be readable for "asciidoc". Before you
make any changes, please read the use guide at the asciidoc home page
www.methods.co.nz/asciidoc and try to adapt to the style used here; e.g.
use the single-line section header style ("== header =="). Please do not use
any whitespace other than SPACE (ASCII 0x20) and break lines > 79 chars.
/////////////////////////////////////////////////////////////////////////////
== Copyright ==
Copyright 2007, 2008 Kolja Waschk and the respective authors.
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License, Version 1.2 or any later version
published by the Free Software Foundation. A copy of the license is included in
the section entitled "GNU Free Documentation License".
//=========================================================================
== General ==
=== JTAG ===
// Contributed by Ralf Engels
JTAG basics can be found all over the internet. This section should go into
some more details about working with JTAG. What hardware do you need, what is
the usage of JTAG, where do I get files. What file formats are available...
==== Introduction ====
JTAG (IEEE 1149.1) is a serial interface for testing devices with
integrated circuits. The problem that the JTAG interface was designed to solve
is checking if connections between ICs are OK. Therefore you can set and check
in- and outputs of ICs. In order to save pins and logic a very simple serial
design was invented.
* One pin serial input
* One pin serial output
* One pin clock
* One pin control
The control pin (together with clock) allows to switch device states. A state
machine inside each chip can be controlled, e.g. to reset the device. This
control machine also allows to have two internal shift registers in each device
(although we only have on in- and one output-pin). The registers are called
instruction register (IR) and data register (DR). The current UrJTAG tool
allows you to set the IR and set and get the DR. It doesn't allow you to
directly control the statemachine (yet).
==== Interfaces ====
The simplest interface that you can build is like the Xilinx parallel cable
(also called DLC5). If your device works with a 5V or 3.3V supply voltage then
this device can even be build just with passive parts. (picture missing here)
UrJTAG also supports a number of other interface adapters.
==== Additions ====
In the meantime the jtag specification was used as a basis for programming
flash files and debugging processors. UrJTAG supports programming a couple of
different flash devices. It also supports programming of non-flash devices via
svf files. UrJTAG does not support debugging yet. Other open source solutions
such as OpenOCD allow you to debug ARM processors with gdb.
==== BSDL and UrJTAG data files ====
The BSDL file format describes the jtag interface for one IC. It is a VHDL
syntax with the needed information (like pin-names, register lengths and
commands) that is usually done by the supplier. e.g. Xilinx BSDL files are
all included in their free web-pack (using file extension ".bsd").
UrJTAG uses a different file format internally. So in order to add a new device
to UrJTAG you need to convert those files and produce a directory structure.
Currently there are at least three tools available to do that; included with
UrJTAG is "bsdl2jtag". Please ask on the mailing list in case of problems with
that. Please also send proven working files back to this project.
Starting with post-0.7 releases, UrJTAG contains a BSDL subsystem that
retrieves the descriptions for chips in the chain from BSDL files on the
fly. Be aware that this feature is currently experimental and may not work
with every BSDL file yet.
==== SVF files ====
The SVF file format contains a number of high level commands to drive the jtag
bus. For example you can shift the IR or DR and even check for the results.
The Xilinxs impact and Altera QuartusII tools allow you to write this file to
program devices.
The player has been developed according to the "Serial Vector Format
Specification", Revision E, 8 March 1999 issued by ASSET InterTech, Inc. The
full specification can be found at
http://www.asset-intertech.com/support/svf.pdf
UrJTAG features an "SVF player" that can read SVF files and perform the
described actions on the bus.
SVF parser and lexer are also copyright 2002, CDS at http://www-csd.ijs.si/.
They have been reused from the "Experimental Boundary Scan" project at
http://ebsp.sourceforge.net/.
==== JAM/STAPL files ====
Another format for describing actions over JTAG interfaces is STAPL, actually
standardized as JEDEC "JESD-71A". Compared to SVF, it looks more like an
actual programming language and features looping, conditional execution, and
more. STAPL is not yet supported by UrJTAG.
//------------------------------------------------------------------------
=== UrJTAG ===
// Written by K.Waschk
==== Introduction ====
UrJTAG Tools is a software package which enables working with JTAG-aware (IEEE
1149.1) hardware devices (parts) and boards through JTAG adapter.
This package has open and modular architecture with ability to write
miscellaneous extensions (like board testers, flash memory programmers, and so
on).
JTAG Tools package is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under certain
conditions. There is absolutely no warranty for JTAG Tools. Please read
COPYING file for more info.
WARNING: This software may damage your hardware!
Feedback and contributions are welcome.
==== About this document ====
This documentation is far from being complete. You're encouraged to amend and
supplement it and submit your changes in the Bugs or Enhancements tracker
at the UrJTAG website.
==== UrJTAG Website ====
The most current version of this documentation and UrJTAG sourcecode
is always available from the project homepage at http://www.urjtag.org
==== The name "UrJTAG" ====
I (Kolja) favour short names, so I thought about adding only a few
letters to "JTAG". The prefix "Ur" in German means "ancestral", an "Ur-Vater"
is a forefather. UrJTAG shall become the forefather, the prototype for many
other JTAG tools. By mere chance the "Ur" is also another name for an aurochs,
an animal similar to the GNU...
==== Authors, contributors, ... thanks ====
A list of contributors is maintained in the file THANKS in the source
distribution.
==== UrJTAG and openwince JTAG Tools ====
The JTAG Tools originally were developed by Marcel Telka as part of
the openwince project. Still a large portion of the source code is his work.
However, the last release of the JTAG tools was version 0.5.1 in 2003. After a
few years the development completely stalled. Every few months or so on the
project's mailing list someone asked about continuing, but a critical mass
wasn't reached before late 2007. A fork of the JTAG tools was created under the
wings of the UrJTAG project at Sourceforge.
//------------------------------------------------------------------------
=== System requirements ===
//Copied from original README
==== Supported host operating systems ====
JTAG Tools should run on all Unix like operating systems including MS Windows
with Cygwin installed.
==== Required software for running UrJTAG ====
Required only for MS Windows:
* current Cygwin net installation from http://cygwin.com
* ioperm package (a part of the standard Cygwin net installation)
It may be necessary to run the command "ioperm -i" to install the IOPERM.SYS
driver in the system.
If UrJTAG was compiled to use the readline library, it has to be present on
the system as well. It's probably a standard part of your distribution.
More software is needed if you want to compile UrJTAG (which you probably want
because currently no pre-compiled binaries are avaible...). See "Installation"
below.
==== Supported JTAG adapters/cables ====
See 'help cable' command for up-to-date info.
* Arcom JTAG Cable
* Altera ByteBlaster/ByteBlaster II/ByteBlasterMV Parallel Port Download Cable
* Altera USB-Blaster and compatible http://www.ixo.de/info/usb_jtag
* Xilinx DLC5 JTAG Parallel Cable III
* ETC EA253 JTAG Cable
* ETC EI012 JTAG Cable
* Ka-Ro TRITON (PXA255/250) JTAG Cable
* Keith & Koep JTAG Cable
* Lattice Parallel Port JTAG Cable
* Mpcbdm JTAG Cable
* Macraigor Wiggler JTAG Cable
* Amontec JTAGkey (FT2232-based)
* Olimex ARM-USB-JTAG (FT2232-based)
* Olimex ARM-USB-TINY (FT2232-based)
* OOCDLink-s (FT2232-based) (experimental) http://www.joernonline.de/dw/doku.php?id=projects:oocdlink:2_oocdlinks
* Other FT2232-based USB JTAG cables (experimental)
* Xverve Signalyzer Tool (FT2232-based) (experimental)
* Turtelizer 2 (FT2232-based) (experimental) http://www.ethernut.de/en/hardware/turtelizer/
* USB to JTAG Interface (FT2232-based) (experimental) http://www.hs-augsburg.de/~hhoegl/proj/usbjtag/usbjtag.html
* Xilinx Platform USB Cable (experimental)
==== JTAG-aware parts (chips) ====
The data/ directory of the UrJTAG installation has some more, but at
least the following are supported:
* Altera EP1C20F400
* Altera EPM7128AETC100
* Analog Devices Sharc-21065L
* Atmel ATmega128 (partial support)
* Broadcom BCM1250
* Broadcom BCM3310 (partial support)
* Broadcom BCM5421S
* Broadcom BCM4712 (partial support)
* DEC SA1100
* Hitachi HD64465
* Hitachi SH7727
* Hitachi SH7729
* IBM PowerPC 440GX
* Intel IXP425
* Intel SA1110
* Intel PXA250/PXA255/PXA260/PXA261/PXA262/PXA263
* Lattice LC4032V
* Lattice M4A3-64/32
* Lattice M4A3-256/192
* Motorola MPC8245
* Samsung S3C4510B
* Sharp LH7A400
* Toshiba TX4925/TX4926
* Xilinx XC2C256-TQ144
* Xilinx XCR3032XL-VQ44
* Xilinx XCR3128XL-CS144
* Xilinx XCR3128XL-VQ100
* Xilinx XCR3256XL-FT256
==== Flash chips ====
NOTE: Not all chips are supported in every possible configuration, there may
be untested combinations of chip type, bus width, ...
* Intel 28FxxxJ3A (28F320J3A, 28F640J3A, 28F128J3A)
* Intel 28FxxxK3 (28F640K3, 28F128K3, 28F256K3)
* Intel 28FxxxK18 (28F640K18, 28F128K18, 28F256K18)
* AMD Am29LV64xD (Am29LV640D, Am29LV641D, Am29LV642D)
* AMD Am29xx040B (Am29F040B, Am29LV040B)
//------------------------------------------------------------------------
=== Compilation and installation ===
==== Required software for compiling UrJTAG ====
To run autogen.sh, you need autoconf and automake, bison, and a recent flex.
Flex 2.5.4a as it comes with Cygwin will work but some parts of UrJTAG (namely
the SVF player) become more verbose if Flex 2.5.31 or newer is used. Building
the BSDL subsystem files requires Flex 2.5.33 or newer. The configure script
will compare the availble Flex version against these preconditions and enables
or disables the related features.
Furthermore, libtool should be available, and "devel" versions of the following
packages:
* gettext
* readline (not needed, but really eases interactive use)
* ioperm (needed only for Cygwin)
==== Required libraries for USB support ====
For USB adapter support (including support for parallel port adapters attached
to USB-to-parallel converters), one or more additional libraries are required.
Many USB JTAG adapters and USB-to-parallel converters are based on chips
made by FTDI. To support these, either intra.net's "libftdi" or FTDI's
"FTD2XX" library can be used.
On many modern Linux distributions, libftdi is available as a precompiled
package and can be installed using the distribution's package management system
(e.g. "apt-get libftdi-dev" for Debian and Ubuntu). If it isn't available or
you don't run Linux, you can get it from
* http://www.intra2net.com/de/produkte/opensource/ftdi/
Alternatively, you can use the FTD2XX library from the chip manufacturer FTDI.
It is available for Linux and Windows. To use the library for Windows in a
Cygwin environment, first get it from:
* http://www.ftdichip.com/Drivers/D2XX.htm
Unzip the CDM*.zip to some directory and tell UrJTAG about this directory
during the configure step before actual compilation:
./configure --with-libftd2xx=/cygdrive/c/windows/temp/CDM_Drivers
All other USB JTAG adapters can be supported only if libusb is installed.
There is a libusb-win32 variant that can be used in a Cygwin environment:
* http://libusb.sourceforge.net (libusb)
* http://libusb-win32.sourceforge.net (libusb for Windows)
For specific notes regarding the use of these libraries in a Cygwin
environmen, see below.
==== Installing from source tar.gz ====
The installation follows the standard configure, make, make install scheme:
tar xzvf urjtag.tar.gz
cd ../jtag
./configure
make
make install
==== Installing from Subversion repository ====
If you want to try the very newest version of UrJTAG...
svn co http://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk urjtag
cd urjtag/jtag
./autogen.sh
# ./configure done by autogen.sh; run it here with special options if needed
make
make install
==== Linking to FTD2XX.DLL in Cygwin environment ====
Before running configure, get the D2XX drivers from FTDI.
* http://www.ftdichip.com/Drivers/D2XX.htm (FTDI FTD2XX library)
Unzip the archive into a directory of your choice (probably a choice
without spaces in the name is better) and afterwards run configure with the
"--with-ftd2xx" pointing to that directory, e.g.
./configure --with-ftd2xx="/cygdrive/e/temp/cdm"
Configure should now report
FTDI cable support
...
via libftd2xx : yes
==== Using LibUSB-Win32 in Cygwin environment ====
Before running configure, install the LibUSB-Win32 "filter" driver from SF.
* http://libusb-win32.sourceforge.net
Then point configure to the directory where LibUSB-Win32 was installed (it
might give problems if the path contains spaces, as "Program Files" does!):
./configure --with-libusb="/cygdrive/c/Programme/LibUSB-Win32/"
==== Building the BSDL subsystem ====
As mentioned above, building the BSDL lexer requires Flex 2.5.33 or newer. If
the detected Flex version is not recent enough, configure will disable the
BSDL subsystem. The detection result is summarized at the end of configure:
jtag is now configured for
...
Build BSDL subsystem : yes
Flex is only required when you're working on a check-out of the Subversion
repository. In this case Flex has to be called to transform bsdl_flex.l to
bsdl_flex.c. When you're compiling from released sources, the local Flex
version is not relevant since the output file of Flex is part of the
tarball. I.e. even if the local Flex fails the check, the BSDL subsystem is
enabled and will be compiled from the released C files.
//=========================================================================
== Usage ==
=== Quick start ===
// Contributed by Ralf Engels
==== Run the software ====
Connect your JTAG adapter between your PC and target device and turn
on your device.
To run JTAG Tools type "jtag" and press Enter. jtag should start and
display some initial informations. Output should end with line like this:
This is "jtag command prompt". Type "help" and press Enter for initial help
about available commands. To exit JTAG Tools type "quit" and press Enter.
==== Configure the cable ====
Type "help cable" for list of supported JTAG cables.
Type "cable" command with arguments. Example:
jtag> cable EA253 parallel 0x378
Initializing ETC EA253 JTAG Cable on parallel port at 0x378
==== Detect parts on the JTAG chain ====
Type "detect" at the jtag command prompt:
jtag> detect
Your output should look like this:
IR length: 5
Chain length: 1
Device Id: 01011001001001100100000000010011
Manufacturer: Intel
Part: PXA250
Stepping: C0
Filename: /usr/local/share/urjtag/intel/pxa250/pxa250c0
If you get empty output or an error message your JTAG adapter is not connected
properly, or your target board doesn't work, or it is turned off.
The "detect" command is required before all other commands.
==== Print current JTAG chain status ====
jtag> print chain
No. Manufacturer Part Stepping Instruction Register
---------------------------------------------------------
0 Intel PXA250 C0 BYPASS BR
==== Sample device pin status ====
jtag> instruction SAMPLE/PRELOAD
jtag> shift ir
jtag> shift dr
jtag> dr
1000110010000010000110010111111111111111111001101110...
jtag> print chain
No. Manufacturer Part Stepping Instruction Register
------------------------------------------------------------
0 Intel PXA250 C0 SAMPLE/PRELOAD BSR
jtag> get signal BOOT_SEL[0]
BOOT_SEL[0] = 0
jtag>
Note: BSR is "Boundary Scan Register"
==== Burn flash connected to the part ====
jtag> flashmem 0 brux.b
0x00000000
Note: Supported configuration is 2 x 16 bit only
BOOT_SEL: Asynchronous 32-bit ROM
2 x 16 bit CFI devices detected (QRY ok)!
program:
block 0 unlocked
erasing block 0: 0
addr: 0x00002854
verify:
addr: 0x00002854
Done.
jtag>
or:
jtag> flashmem msbin xboot.bin
Note: Supported configuration is 2 x 16 bit only
BOOT_SEL: Asynchronous 32-bit ROM
2 x 16 bit CFI devices detected (QRY ok)!
block 0 unlocked
erasing block 0: 0
program:
record: start = 0x00000000, len = 0x00000004, checksum = 0x000001EB
record: start = 0x00000040, len = 0x00000008, checksum = 0x000001B0
record: start = 0x00001000, len = 0x00002B30, checksum = 0x00122CAB
record: start = 0x00004000, len = 0x00000160, checksum = 0x0000684B
record: start = 0x00005000, len = 0x00000054, checksum = 0x000008EE
record: start = 0x00005054, len = 0x00000030, checksum = 0x00000DA9
record: start = 0x00000000, len = 0x00001000, checksum = 0x00000000
verify:
record: start = 0x00000000, len = 0x00000004, checksum = 0x000001EB
record: start = 0x00000040, len = 0x00000008, checksum = 0x000001B0
record: start = 0x00001000, len = 0x00002B30, checksum = 0x00122CAB
record: start = 0x00004000, len = 0x00000160, checksum = 0x0000684B
record: start = 0x00005000, len = 0x00000054, checksum = 0x000008EE
record: start = 0x00005054, len = 0x00000030, checksum = 0x00000DA9
record: start = 0x00000000, len = 0x00001000, checksum = 0x00000000
Done.
jtag>
//------------------------------------------------------------------------
=== JTAG commands ===
// Various authors...
==== Overview ====
Following is a list of commands currently supported by jtag and some
example usage.
*bit*:: define new BSR bit
*bus*:: change active bus
*bsdl*:: manage BSDL files
*cable*:: select JTAG cable
*detect*:: detect parts on the JTAG chain
*detectflash*:: detect parameters of flash chips attached to a part
*discovery*:: discovery of unknown parts in the JTAG chain
*dr*:: display active data register for a part
*endian*:: set/print endianess
*eraseflash*:: erase flash memory by number of blocks
*flashmem*:: burn flash memory with data from a file
*frequency*:: setup JTAG frequency
*get*:: get external signal value
*help*:: display this help
*include*:: include command sequence from external repository
*initbus*:: initialize bus driver for active part
*instruction*:: change active instruction for a part or declare new instruction
*part*:: change active part for current JTAG chain
*peek*:: read a single word
*poke*:: write a single word
*print*:: display JTAG chain list/status
*quit*:: exit and terminate this session
*readmem*:: read content of the memory and write it to file
*register*:: define new data register for a part
*script*:: run command sequence from external file
*set*:: set external signal value
*setdevice*::: force device detection
*shift*:: shift data/instruction registers through JTAG chain
*signal*:: define new signal for a part
*svf*:: execute svf commands from file
Some tools derived from the same openwince JTAG Tools code base as UrJTAG
know additional commands, which are not supported in UrJTAG. See the section
about "Unsupported commands", below, about workarounds.
==== Basic commands ====
===== quit =====
This command closes the jtag console.
===== help =====
Without additional parameter it gives an overview of the available commands.
With a parameter you can get more information about any of the commands.
Example:
jtag> help cable
Most cable drivers require some more details about the cable to start properly.
To learn about the details, use the "cable" command with the name of the cable
followed by the word "help". Example:
jtag> cable wiggler help
===== include =====
Run commands from a named script file installed with UrJTAG. The directory prefix
is added automatically (e.g. /usr/share/urjtag/, depending on your installation).
For example, the following startup sequence configures the cable, chain, and loads
definitions and bus driver for a Samsung S3C4510B CPU to peek its memory at 0x0:
jtag> cable wiggler ppdev /dev/parport0
jtag> detect
jtag> include samsung/s3c4510b/s3c4510b
jtag> peek 0x0000
===== script =====
Run commands from a named script file located anywhere. No directory prefix is added.
A number X may be specified after the name of the script file, causing the script to
be run X times.
==== Part definition commands ====
The following commands are also used in the data files to define a device (IC)
on the jtag bus. It is not recommended to use these commands in an interactive
session. Instead you should produce a device definition file out of a .bsd file
using one of the supplied tools.
* bit
* register
* signal
==== Flash commands ====
These commands can be used if the device supports flashing.
* detectflash
* flashmem
* eraseflash
==== Chain management ====
===== cable =====
Sets and initialized the cable driver. This is usually the first
command that you are executing in a session. Example:
jtag> cable EA253 parallel 0x378
Initializing ETC EA253 JTAG Cable on parallel port at 0x378
For a parallel cable using the ppdev driver you would use this:
jtag> cable DLC5 ppdev /dev/parport0
If you get an error, it may be that the parallel port kernel driver
was compiled as a module in your Linux kernel and wasn't loaded automatically.
Then you should try to load the ppdev driver manually (with root rights outside
the jtag shell):
modprobe ppdev
modprobe parport
modprobe parport_pc
===== detect =====
Detects devices on the bus. Example:
jtag> detect
IR length: 5
Chain length: 1
Device Id: 01011001001001100100000000010011
Manufacturer: Intel
Part: PXA250
Stepping: C0
Filename: /usr/local/share/jtag/intel/pxa250/pxa250c0
During "detect", UrJTAG searches through the files in its database (usually in
/usr/share/urjtag) to find a match for the manufacturer, revision and part
number for the IDCODE read from the part. However, not all parts identify
themselves in a way that is useful for "detect". For example, many chips with
an ARM processor core inside present an IDCODE that may be specific to the the
particular core inside the chip (e.g. ARM7TDMI), but doesn't tell about the
actual manufacturer of the chip. In such case, the data for the part has to be
included manually. See also the documentation for the "include" command.
==== Highlevel commands ====
===== svf =====
The SVF player operates on a single part in the scan chain. Therefore, you
have to bring up the jtag software, specify a cable and detect the scan
chain beforehand.
The player will establish a new instruction called "SIR" and a new register
called "SDR". They are used internally by the respective SVF commands and are
reassigned with new values as the player advances through the file. It is not
recommended to use them outside of the SVF player as their content is dynamic.
An example session:
jtag> cable ppdev /dev/parport0 DLC5
Initializing Xilinx DLC5 JTAG Parallel Cable III on ppdev port /dev/parport0
jtag> detect
IR length: 5
Chain length: 1
Device Id: 10010000101000100000000010010011
Manufacturer: Xilinx
Part: XC2S300E-PQ208
Stepping: 9
Filename: /usr/local/share/jtag/xilinx/xc2s300e-pq208/xc2s300e-pq208
jtag> part <desired part of the scan chain>
jtag> svf <SVF file for selected part>
jtag> instruction BYPASS
jtag> shift ir
jtag> part <next part>
jtag> svf <SVF file for selected part>
jtag> instruction BYPASS
jtag> shift ir
It is recommended to set the part's instruction register to BYPASS although
most SVF files do this at the end. By setting the instruction explicitely to
BYPASS the output of the print command will always show meaningful
information.
The SVF player will issue messages when situations arise that cannot be
handled. These messages are classified as warnings or errors depending on
whether the player can continue operation (warning) or not (error).
In case the TDO parameter of an SDR command leads to a mismatch the player
issues a warning and continues. If the player should abort in this case then
specify 'stop' at the svf command.
.Limitations and Deficiencies
*****************************
Several limitations exist for the SVF player.
It has been tested so far with files generated by these tools:
- Xilinx ISE WebPack 6.3.02i - 9.1.02i
- Altera Quartus II 4.1sp1 - 7.0
Configuration for these devices has been tested so far:
- Altera EPC1C12Q240
- Altera MAX3032, EPM3032ALC44
- Altera MAX3064, EPM3064ALC44
- Altera MAX7032, EPM7032SLC44
- Altera MAX7064, EPM7064SLC44, EPM7064STC44
- Xilinx Spartan-IIE, XC2S300E-PQ208
- Xilinx Spartan-3, XC3S1000-FG456, XC3S5000-FG900
The implementation of some SVF commands has deficiencies.
- HIR, HDR commands not supported. +
Their functionality should be covered by the part concept of JTAG Tools.
- PIO command not supported.
- PIOMAP command not supported.
- RUNTEST SCK not supported. +
The maximum time constraint is not guaranteed.
- SIR +
No check is done against the TDO parameter.
- TRST +
Parameters Z and ABSENT are not supported.
- TIR, TDR commands not supported. +
Their functionality should be covered by the part concept of JTAG Tools.
Operation can be slowed down significantly when the FREQUENCY command has
been specified. This is not a problem of the SVF player itself but seem to
happen when the frequency of UrJTAG is set to a value larger than 0.
Configuration takes very long although the maximum allowed frequency is 10 MHz.
Consider to comment out the FREQUENCY command at the beginning of the SVF file.
*****************************
===== bsdl =====
The 'bsdl' command is used to set up and test the underlying BSDL subsystem of
UrJTAG.
Whenever 'detect' encounters a new part, a configuration process is
started. This involves matching the retrieved IDCODE against the part
descriptions in /usr/share/urjtag as described above. However, before this
database is searched for a suitable description, the BSDL subsystem is started
and searches for BSDL file that matches this device. If it finds a matching
file, traversal of the /usr/share/urjtag database is skipped. If not, then
this standard process follows.
To tell the BSDL subsytem where to look for BSDL files, the 'bsdl path
pathlist' command has to be issued prior to 'detect'. The contents of
'pathlist' must be a semicolon-separated list of directories where BSDL files
are located. This list is stored by 'bsdl path' and is used lateron when
'detect' calls the BSDL subsystem.
IMPORTANT: The BSDL subsystem applies the first BSDL file that parses without
errors and that contains the correct IDCODE. Scanning the specified
directories happens in extactly the given order. Inside a directory however,
the order depends largely on your filesystem's behavior.
Further details of the 'bsdl' command:
- bsdl path <path1>[;<path2>[;<pathN>]] +
set paths for locating BSDL files
- bsdl debug on|off +
switches debug messages on or off
- bsdl test [file] +
reads file (if specified) or all files found via 'bsdl path' and
prints a short status, an active part is not required
- bsdl dump [file] +
reads file (if specified) or all files found via 'bsdl path' and
prints all configuration commands, an active part is not required
TIP: The 'bsdl dump file' command implements the same functionality as
bsdl2jtag.
==== Unsupported commands ====
===== setdevice =====
This command was only there to support the SHARC 21065L processor,
which has no IDCODE and therefore can't be initialized correctly by
just running "detect". However, the proper initialization can be done
after "detect" by loading the proper declarations and bus driver manually:
jtag> include analog/sharc21065l/sharc21065l
//========================================================================
== Internals ==
This section yet is only a placeholder for the information that will
be added soon...
=== Files ===
==== Source code Overview ====
doc/::
Documentation
data/::
Part descriptions (Data files)
include/::
C header files
src/::
C source code
src/bsdl::
BSDL subsystem
src/bus::
Bus driver for various CPUs and other parts
src/cmd::
Implementation of the commands for the "jtag" shell
src/flash::
Flash detection and programming algorithms
src/jim::
JIM, the JTAG target simulator
src/lib::
Utility functions
src/part::
Functions for accessing specific parts in a chain
src/svf::
SVF player
src/tap::
Functions for accessing the chain in general
//------------------------------------------------------------------------
=== Drivers ===
* Cable-specific drivers
* Parport drivers
* TAP drivers
* Chain drivers
* Bus drivers
* Flash drivers
* Commands
==== Cable-specific drivers (src/tap/cable) ====
Cable-specific drivers are those which are visible to the user through
the "jtag" command shell. They're listed in response to the "help cable"
command. Each driver has to provide the following functions:
* connect(), init() - Initialization
* done(), cable_free(), disconnect() - Cleaning up
* clock(), get_tdo(), transfer() - immediate JTAG activities
* flush() - internally used to actually perform JTAG activities
* help() - a help text to be displayed by the jtag command shell
===== Initialization =====
After allocating a "cable_t" structure, a pointer to it and further
parameters (as strings) have to be passed first to the selected cable's
connect() function.
Following that, the init() function is called via cable_init(). If cable_init()
returns a zero value, all is fine and the cable is ready for use.
===== Cleaning up =====
There are two functions for actual cleanup:
* done() is responsible for driving the hardware to a safe and consistent state.
* cable_free() then can be used to clean up eventually extra allocated memory etc.
Both are usually called from chain_disconnect().
An additional mechanism allows to clean up if a disconnection was detected by
the low level driver (e.g. USB or parallel port driver). A cable has to provide
a disconnect() function for this purpose:
1. Low level (e.g. parport) driver calls cable driver->disconnect()
2. cable driver->disconnect() calls chain_disconnect()
3. chain_disconnect() calls cable driver->done()
4. chain_disconnect() then calls cable driver->cable_free()
After return from chain_disconnect() to cable driver->disconnect(), the cable_t
structure has been freed and must not be accessed anymore.
===== JTAG Activities =====
Currently the API provides five different functions for performing operations
at the JTAG interface on the low level signal level (using the four signals
TMS, TCK, TDI, and TDO).
* clock(tms,tdi,n) takes values for TMS and TDI output as its parameters, ensures that actual cable signals are set accordingly, and does a 0-1 transition on TCK (n times)
* get_tdo() returns the current value at the TDO input.
* set_trst(x) sets the TRST signal and returns the current value.
* get_trst() returns the current value of the TRST signal.
For many JTAG adapters, there's almost no delay when doing alternating clock()
and get_tdo(). Writing and reading happens immediately and the result is
available immediately as well. This is the case with most parallel port
adapters (but not when attached to USB-to-parallel adapters or USB docking
stations) and memory mapped IO (e.g. general purpose I/O pins of
microcontrollers).
But there are adapters, especially USB and Ethernet based adapters, which
exhibit a rather long delay between the initiation of reading a bit and the
delivery of the value of the bit. It is at least 1 millisecond with USB,
which would limit the transfer rate to 1 kHz. One way to workaround this
is to transmit bits compacted into bytes and chunks of bytes, which is
possible with the transfer() function.
* transfer(in, out)
The transfer() function does a series of TCK pulses, with data for TDI read as
bytes from memory. The bytes are automatically serialized. TMS is set to zero
during transfer()s. Optionally, prior to each bit shifted out to the interface,
TDO input can be read into memory (deserialized into a byte array of the same
size as the input array).
It still doesn't yield much improvement if the operation consists of many read
and write transitions (e.g. repeatedly writing an instruction and some data
register values, then reading from the data register, as it is necessary for
memory access). For that reason, the above functions are also available in
variants that don't cause immediate activity, but rather schedule it for later.
In the API, they're visible as
* cable_defer_clock()
* cable_defer_get_tdo()
* cable_defer_set_trst()
* cable_defer_get_trst()
* cable_defer_transfer()
These functions aren't implemented in the cable driver (but currently in
src/tap/cable.c). The cable driver just has to provide a flush() function to
actually execute the queued activity in some cable-specific optimal way, and
to store the results of get_tdo() and transfer() activity. The caller later
can pick up the results using these functions (implemented in cable.c):
* cable_get_tdo_late()
* cable_get_trst_late()
* cable_transfer_late()
As an example, consider the following sequence of activities:
1. clock()
2. get_tdo()
3. clock()
4. get_tdo()
If the result of the first get_tdo() isn't absolutely required before the
second clock(), the sequence can be optimized into the following sequence (if
1. defer_clock()
2. defer_clock()
3. flush()
4. get_tdo_late()
5. get_tdo_late()
The next sections explain the queueing mechanism and its limits in detail.
===== When flushing occurs ======
The cable_flush() function is used to flush the queue towards the cable. It
takes one additional argument, "how_much", which may be one of
* OPTIONALLY: The cable driver may flush if it's reasonable (e.g. if the
queue has been filled so that some buffer limit for the cable interface
is reached). It would be wise to flush early to keep the queue small, if
there is no point in queueing up more items because the transfer to the
cable would have to be split into smaller chunks anyway. This is used by
UrJTAG immediately after adding items to the queue.
* TO_OUTPUT: The cable driver should at least flush as much so that one
output becomes available in the output queue. If there's already something
in the output queue, this should be interpreted similar to OPTIONALLY. This
is used by UrJTAG immediately before it wants to use that output.
* COMPLETELY: The cable driver has to flush the queue completely. This is
used by UrJTAG immediately before actions that circumvent the queueing
such as calls to the legacy clock/get_tdo functions. It could also be
used by application code to ensure that some action is actually done in
time.
===== JTAG activity queueing =====
The source in src/tap/cable.c provides to important functions to access the
two queues "todo" (with activity to be done) and "done" (with results):
* cable_add_queue_item
* cable_get_queue_item
In src/tap/cable/generic.c you'll find two implementations of dequeueing
algorithms, i.e. implementations of the flush() function. These could be used
by any new cable driver unless it provides a more sophisticated algorithm
itself:
* generic_flush_one_by_one() simply calls the "classic" functions one after
another. The performance of the cable driver using this implementation will
be the same whether the immediate or defer variants of the functions are used.
* generic_flush_using_transfer() tries to optimize as many clock() and
get_tdo() by transforming them into calls to transfer() instead. This can
give a slight advantage.
The generic implementations also serve as a template for new cable-specific
implementations.
===== Generic implementations =====
As a reference and in many cases completely sufficient for new cables, take a
look at the code in src/tap/cable/generic.c, which contains generic routines,
suitable for parallel port based cables (and some for other types of cables as
well).
=== Data file format ===
// By Marcel Telka
JTAG declarations files are located in directory "data". The files contains
common part specific JTAG information in parseable form, e.g. list of the JTAG
commands, boundary scan register, list of JTAG registers, etc.
Syntax of the JTAG declaration file is defined in the following subsections.
==== General rules ====
JTAG declaration file is text file which consists of lines. Empty lines are
ignored. Text after first "#" on the line to the end of line is ignored. This
is useful for comments. All other lines are significant.
Each significant line consists of tokens separated by whitespace. Whitespace
could be spaces and/or tabs.
==== Signal Definition ====
Signal definition line consists of word "signal" followed by whitespace and
signal name (without spaces in the name). Rest of the line should contain
whitespace separated list of pins of the part. This list is currently not used
for any purpose in JTAG Tools. It is intended for future use.
//------------------------------------------------------------------------
=== Development ===
==== Future Plans ====
- C API and library package
- Bindings for Python, Perl, ...
- TCP/IP access
- New cable drivers
- ...
==== How to contribute ====
* Using Subversion
* Create and submit a patch
* Use SourceForge trackers
//========================================================================
== F.A.Q. ==
For a list of known problems in current versions, please also check the "Bugs"
tracker at the UrJTAG website!
Q. When I type "cable parallel 0x378 DLC5" (in a Cygwin environment) I get "Unknown port driver: parallel"?::
A. Please install the Cygwin ioperm package, and re-configure/compile.
Q. When I type "cable parallel 0x378 DLC5" (in a Cygwin environment) I get "Error: Cable initialization failed!".::
A. Please install ioperm.sys driver using `ioperm -i` command.
Q. When running autogen.sh, I get "Can't exec "autopoint": No such file or directory"::
A. You need the headers for gettext (e.g. Debian package "gettext-devel").
Q. During compilation, I get "svf_bison.y: No such file or directory"::
A. You need "bison".
Q. During compilation, I get "flex: can't open ... src/svf/svf_flex.l"::
A. You need "flex"
Q. During compilation, I get "src/svf/svf_flex.l", line 27: unrecognized %option: bison-locations"::
A. You need a newer version of flex. It should be 2.5.31 or newer;
Unfortunately, Cygwin comes with only 2.5.4a. You may try to compile and
install a newer version of flex from source to solve this.
//========================================================================
== Licensing ==
=== Overview ===
Three licenses are used for the UrJTAG project. The GPL is used for most
of the code except for the files in the inclow/ subdirectory; the FDL is
used for this documentation. The files in the inclow/ subdirectory are
subject to different licensing as described in the file inclow/COPYING.
=== GNU Free Documentation License (FDL) ===
.........................................
include::fdl.txt[]
.........................................
=== GNU General Public License (GPL) ===
.........................................
include::gpl.txt[]
.........................................
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