[OpenWrt-Devel] Good jtag usb adapter

Paul Fertser fercerpav at gmail.com
Thu Aug 14 12:46:10 EDT 2014


Ernesto <forosylistas at ernet.com.ar> writes:
> I'd like to enter into the jtag world, and looking for a cheap usb
> adapter, like this ones:
> http://www.dx.com/p/avr-jtag-usb-debugging-emulator-downloader-deep-blue-312848#.U-y5hxpVHeQ
> http://www.dx.com/p/j-link-v8-arm-usb-jtag-adapter-emulator-black-149039#.U-y5jBpVHeQ
> http://www.dx.com/p/ulink2-usb-jtag-emulator-arm7-arm9-cortex-ulink-ii-debug-adapter-156978#.U-y5nBpVHeQ

I'm afraid none of that is an appropriate choice, apart from, probably,
that JLink clone. Unless you runtime-test it, it's hard to tell whether
it would work with OpenOCD or not.

If you're looking for the cheapest solution, then probably the official
FT232H breakout board (with ~47 Ohms series resistors on every signal
line) is the optimal known-to-work solution. If you want something a bit
better, with output buffer and such, then probably TUMPA or Olimex or
Flyswatter2. DP BusBlaster will work too, but I'm afraid its CPLD might
be a bit more sensitive to rough handling and thus less reliable.

If you just want to try JTAGing something right now, you can probably
take any board that has 4 spare GPIOs and use "sysfsgpio" driver or if
you have a raspberrypi, then a faster bcm2835 driver (but do not forget
about matching voltages, and possibly you'll need series resistors there
as well, depends on the target).

Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software!
mailto:fercerpav at gmail.com
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