On Fri, Jun 10, 2011 at 12:35 AM, Andreas Fritiofson
<andreas.fritiofson at gmail.com
<https://lists.berlios.de/mailman/listinfo/openocd-development>> wrote:
>/ What are you talking about? Not all ftdi dongles are wired like this =>
/>/ there is no universal default setting suitable for all dongles.
/
Uhm, I read bad at 3am :-) You told that not always setting Hi-Z on FT
chip equals Hi-Z on JTAG connector.. right? This is obvious and I told
that there might be strange buffer design where Hi-Z activates its
outputs (not LOW as should). I gave you and example of good design of
buffer design allowing FT chip also to work with SWD and possibly any
other transport. For this kind of good design there _is_ universal
behavior (read more below) :-)
Also note what Laurent told:
On Tue, Jun 7, 2011 at 9:34 AM, Laurent Gauch <laurent.gauch at amontec.com
<https://lists.berlios.de/mailman/listinfo/openocd-development>> wrote:
>/ Without doing something within deinit, we still have strange openocd
/>/ inter-session phenomena (as TRST still driven instead to be TRISTATE ...
/>/ really important for debugging TI OMAP ! )
/
Not sure if OUTPUT-HIGH for FT2232 means Hi-Z but most buffers you
mention in those interfaces are tri-state buffers from what I have
seen on ~5 different devices. Tri-state buffers are active-low, so
setting pins to input (Hi-Z) should give Hi-Z on connector in most
cases... strange designs may require layout-specific quit function but
this is trivial to add :-)
For OpenOCD, the important is not to know if a dongle has active-low or
active-high buffer ...
The important is to deinit correctly.
1. deinit the specific layout if needed
2. put mppse in default configuration
3. put Channel X pins of FTDI in initial state
3. reset the bitbang mode
Then close the handle.
--
CeDeROM, SQ7MHZ, http://www.tomek.cedro.info
Laurent
http://www.amontec.com
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