Calypso JTAG

Drasko DRASKOVIC drasko.draskovic at
Wed Jun 8 08:55:03 UTC 2011

On Wed, Jun 8, 2011 at 8:48 AM, Harald Welte <laforge at> wrote:
> On Sat, Jun 04, 2011 at 01:50:46AM +0200, Drasko DRASKOVIC wrote:
>> did anyone succeeded on attaching to JTAG port of Calypso ?
>> I was looking at the docs here :
>>, especially this :
>> so I was wondering if someone has used JTAG, specifficaly with OpenOCD
>> or UrJTAG ?
> I think I remember somebody had experimented with OpenOCD, and there was
> some problem related to the initial reset of the CPU. Something
> regarding the PLL setup, perhaps?  But apart from that, it seemed to be
> working.

Hi Harald,

Good news. Normally PLL and RAM (and all other) configuration can be
done by OpenOCD scripts just after reset (during reset-init procedure
of OpenOCD). Since there is bootcode already implemented, it would
should be a matter of rewriting this C/ASM initialization into OpenOCD
Jim TCL start-up scripts (but I guess it is just a few reg writes...)

> (of course only on those phones that expose JTAG, which specifically is
>  _not_ the C123 we have seen,

Hmm... I was little bit confused so I needed clarification. When you
say that C123 do not expose JTAG, what are then TDI, TDO and  TMS pins
here : ?
I thought that they are standard JTAG signals and that we can connect
JTAG probe connector directly there. After that alls should work with
OpenOCD because it have great support for ARM7TDMI.

> but only C115, C117 and C155).

I tried to look for a schematic for C115/C117, but link on Osmocom
site seems to be dead :
I'll search on the net later this evening...

> I don't remember who did that, though.  Let's hope they still read this
> list and respond separately.
> We didn't really make use of it as most people have C123, and also we
> have not really needed it during our development of the existing code.

Well, it is true that for PS development it is not essential. However,
I think that for the platform development - RTOS, BSP/HAL, drivers,
etc... it can be really handy. It is powerful tool, and it would be a
shame not to use it if it is only a matter of soldering 5 pins... I am
primarily looking at this for a OS porting/debugging purposes.


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