Re: [avr-gcc-list] r-engineering the JTAG-ICE protocol

[Jesper Hansen]

Hi Karl,

I've been thinking of the same thing. Haven't started yet, but are
considering buying a JTAGICE so I can hack it.

The protocols is as you say synchronous, so a simple program 
could be written on a mega16x or 8515 to log all the communication
between the ICE and the CPU being debugged.
Or, if it's too fast, the good old way with a storage scope works
too.

Please keep us informed about your progress.

/Jesper 

----- Original Message ----- 
From: "Karl Ran" <address@hidden>
To: <address@hidden>
Sent: Saturday, October 05, 2002 3:23 PM
Subject: [avr-gcc-list] r-engineering the JTAG-ICE protocol


> Hi there!
> 
> I'd like to know if anyone already started to reverse-engineer the
> AVR-onchip-JTAG-ICE command-set on the newer Mega16++ AVRs.
> If not, anyone knows the complexity of the ICE command-sets on the
> microconrollers in general?
> 
> I realy wonder why Atmel put a big Mega163 in its JTAG-RS232 interface.
> 
> How hard can it be?
> JTAG is synchronouns protocol, AFAIK. So it should be quite easy to
> capture, right?
> 
> I'd guess the (binary) commands could look like these:
> Set bp as/ds
> Clr bp as/ds
> read mem
> write mem
> read reg
> write reg
> set pc
> read ICE-status
> read adr-bus history
> stop
> start
> ..
> 
> Am I totaly on the wrong track here?
> 
> Any tips, infos, etc are welcome!
> 
> Karl
> 
> 
> 
> 
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