Uwe Hermann | A slightly paranoid Debian developer

Here's a quick introduction to using a cheap FTDI FT2232H based module (left-hand side on the photo) as a JTAG programmer together with the OpenOCD JTAG software for ARM and MIPS devices. The module I am using for thіs purpose is a DLP Design DLP-USB1232H, which is available from various sources (Digikey, Mouser, Saelig, and probably others) for 20-30 bucks plus shipping, depending on where you live.

By properly connecting the correct pins of the DLP-USB1232H to the target JTAG
device (I used an Olimex STM32-H103 eval board for testing) you can easily abuse the DLP-USB1232H as JTAG programmer. As I chose the proper DLP-USB1232H GPIOs for the TRST and (S)RST pins, OpenOCD even worked out of the box, without having to change a single line of code.

The only thing that's required is to provide OpenOCD with an interface config file that uses the usbjtag "layout". I have already submitted that config file upstream, I guess it should be merged soonish.

The usage is then pretty simple:

  $ openocd -f interface/dlp-usb1232h.cfg -f board/olimex_stm32_h103.cfg

And in another xterm:

  $ telnet localhost 4444
  > init
  > reset halt
  > flash write_image erase fancyblink.bin 0x08000000
  > reset

This flashes the given fancyblink.bin image onto the STM32-H103 eval board via the DLP-USB1232H JTAG programmer, where fancyblink.bin is an example program from my libopenstm32 project (that aims to create a full-blown firmware library for ST STM32 microcontrollers, similar to what avr-libc does for AVRs). Contributions for libopenstm32 (license is GPLv3 or later) are highly welcome btw., hint hint...

  $ git clone git://libopenstm32.git.sourceforge.net/gitroot/libopenstm32/libopenstm32

Full schematics, datasheets, and detailed instructions for the JTAG programmer are available from a small page I created in my Random Projects wiki, which is intended for the various smaller projects I'm working on that don't warrant getting their own domain, wiki, etc:

• http://randomprojects.org/wiki/DLP-USB1232H_and_OpenOCD_based_JTAG_adapter

The Random Projects wiki is open-for-all btw, feel free to use it for any freeish, software or hardware projects of your own if you want.

Anyway, the DLP-USB1232H is a really nice device as it can also be used for many other purposes, such as USB-to-Serial or SPI BIOS chip programming, but more on that in another blog post...

I have mentioned the flashrom utility in my blog in the past. This is a small command line tool which allows you to update your BIOS/coreboot/firmware chips without opening the computer and without any special boot procedures.

Yesterday, flashrom 0.9 was finally released. Here's a short passage from the release announcement:

After nine years of development and constant improvement, we have added support for every BIOS flash ROM technology present on x86 mainboards and every flash ROM chip we ever saw in the wild.

Highlights of flashrom include:

• Parallel, LPC, FWH and SPI flash interfaces.
• 157 flash chip families and half a dozen variants of each family.
• Flash chip package agnostic. DIP32, PLCC32, DIP8, SO8/SOIC8, TSOP32, TSOP40 and more have all been verified to work.
• 75 different chipsets, some with multiple flash controllers.
• Special mainboard enabling code for dozens of nonstandard mainboards.
• No physical access needed. root access is sufficient.
• No bootable floppy disk, bootable CD-ROM or other media needed.
• No keyboard or monitor needed. Simply reflash remotely via SSH.
• No instant reboot needed. Reflash your ROM in a running system, verify it, be happy. The new firmware will be present next time you boot.
• Crossflashing and hotflashing is possible as long as the flash chips are electrically and logically compatible (same protocol). Great for recovery.
• Scriptability. Reflash a whole pool of identical machines at the same time from the command line. It is recommended to check flashrom output and error codes.
• Speed. flashrom is much faster than vendor flash tools.
• Supports Linux, FreeBSD, DragonFly BSD, Solaris, Mac OS X. Please refer to the README for build instructions.

Please note that rewriting your flash chip can be dangerous and flashrom developers make no guarantees whatsoever. That said, many users have successfully replaced proprietary tools such as awdflash, amiflash and afudos with flashrom.

Download: flashrom-0.9.0.tar.gz
SVN: svn co svn://coreboot.org/flashrom/trunk flashrom
Debian: apt-get install flashrom

Do yourself a favor and try flashrom next time you want to upgrade your BIOS. No more floppies or bootable CD-ROMs with DOS/Windows binaries or similar crap. Run flashrom conveniently from the Linux command line, or even via SSH or serial console if you want...