Re: [OpenOCD-user] FT2232 device

[Trampas S. <tr...@gm...>]

Thanks !

What is the cfg file for the dangerousprototypes design/layout?

On Tue, Aug 2, 2016 at 4:04 PM, Tomas Vanek <to...@us...>
wrote:

> Pulling SWDIO to low only is wrong, you should use push-pull for output
> and hi-z for input.
> SWDIO is not an open collector, it is a real bidirectional line.
> See http://dangerousprototypes.com/forum/viewtopic.php?t=2001
>
>
> On 02.08.2016 21:45, Trampas Stern wrote:
>
> I did use a tri-state driver to pull the SWDIO low.
>
> I also added a 10k pull up on the TMS/SWDIO as that even with tri-state
> the SWDIO on the hardware I was using was too week.
>
>
>
> On Tue, Aug 2, 2016 at 3:32 PM, Tomas Vanek <to...@us...
> > wrote:
>
>> On 02.08.2016 19:13, Trampas Stern wrote:
>>
>>> The resistor hack is basically a hack, but would be better if a Schottky
>>> diode was used with a pull up resistor. This would simulate the TDI being
>>> an open collector driver and only pulling down the SWDIO.  Also for some
>>> hardware the debugger should have a pull up on the SWDIO.
>>>
>> Certainly not. Pull up on SWDIO is really weak, just to prevent line
>> floating. Asymmetric drive of open collector with the capacity of a cable
>> would have much steeper failing slope than rising - this would limit
>> reachable frequency.
>>
>> If you don't want to use a hack, you should connect a 3-state driver from
>> TDI output to SWDIO and configure a FT2232 pin as a signal to enable it.
>> See kt-link.cfg.
>>
>> Tomas
>>
>>
>
>