Lpc2000

Hello,

On Wednesday 07 December 2005 23:00, Bertrik Sikken wrote:
>
> Hi Tom,
>
> Thanks for going through the trouble of trying out your wiggler clone.
>
> I think I'm making some progress with my (olimex) wiggler clone
> and the gdb-arm-jtag sources. It appears I can at least get the
> JTAG id code now. I get 4F1F0F0F for an LPC2148, which looks similar
> to the 7F1F0F0F default code that I see in the ARM7TDMI-S docs from ARM.
> Do you remember which idcode you got?
>
The 0x4f1f0f0f is what I get on my lpc2294, so this should be fine.

>
> I needed to do two things to make gdb-arm-jtag work so far:
> 1) wait a bit after the device is reset before accessing JTAG
That's because of Philips' code protection. The test logic is forced into 
reset state whenever the chip is reset, making it impossible to debug right 
out of reset.

> 2) make sure that parallel port bits DATA4 and DATA7 are set
Data4 should be the system reset. Not sure what Data7 is.

>
> Regarding 2), I see that these pins are going somewhere in
> the olimex wiggler clone, but I can't clearly see where
> (could be the output enables or perhaps some kind of power pins)
>
> All the best,
> Bertrik

You should be aware that debugging an ARM7 is different from an ARM9. The 
debug scan-chain of the arm7 has only 33 bits, 32 bit data/address bus + one 
control bit, while the arm9 has 67 bits, 32 bit data, 32 bit address and 
three control bits. Also, the ARM7 has a different pipeline design than the 
ARM9 (3 stages arm7 vs. 5 stages arm9).

If you're interested in working on this topic mail me off-list, I've been 
working on a debugger with a gdb interface for quite some time now, it just 
needs some finishing touches.

Regards,

Dominic