Re: [Openocd-development] adapter_khz ...

[Laurent G. <lau...@am...>]

Antonio Borneo wrote:
> On Thu, Mar 25, 2010 at 9:31 PM, Laurent Gauch
> <lau...@am...> wrote:
>   
>> T H E   S O L U T I O N -----------------------------------
>>
>> The solution is to add the absolute max frequency for a given device when we
>> create a "jtag newtap" as
>> jtag newtap $_CHIPNAME cpu .-freqmax_khz 10000 -irlen 7 -ircapture 0x1
>> -irmask 0x7f -expected-id $_CPUTAPID -expected-id $_CPUTAPID2
>>     
>
> Laurent,
> just my 2 cents contribution....
> Give a look at tcl/interface/parport.cfg
> This interface has one default parameter for parallel port address.
> The default value can be modified, e.g., in the user configuration
> script, without any need to change the interface script.
>
> Can similar arrangement work for you too?
>
> Best Regards
> Antonio Borneo
>   
Hi Antonio,

Thank you for trying to provide a solution  ;-)

Yes, it could be a workaround. But not a final solution.

The JTAG frequency of the chain is not depending on the capability of 
the JTAG Dongle but is depending on the chain itself :
- the target or the daisy chained targets
- the boards layout
- length and termination of the JTAG cable

The first dependence is coming from the targets. If we implement the 
-freqmax in the 'jtag newtap' we can make sure to run JTAG lower than 
the lowest JTAG frequency of any TAP and at any time.

Regards,
Laurent Gauch
  http://www.amontec.com