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

[a . doesschate]

On Sat, Oct 05, 2002 at 06:49:10PM +0200, Torsten Mohr wrote:
> Hi,
> 
> great!  I also wrote some JTAG software for the parallel port to
> debug my ARM7TDMI.  When i read that the ARM controllers also
> have a JTAG port but Atmel won't release its specification
> i thought about reverse engineering it.


Maybe we can bundle some things ...


> 
> Building some hardware that implements a JTAG TAP controller
> could help.  This hardware would get the JTAG signals TMS, TDI,
> TCK, TRST and would behave like a JTAG controller.


This is my idea too !


> This way, the speed of the JTAG-ICE shouldn't be a problem.
> Has anybody measured the speed the JTAG-ICE works with?
> What is the time period of a Clock pulse?

The clock of TCK is about 5 to 5.6 microseconds and can be a bit longer
and depends on which state the JTAG TAP machine is in. Specifically
while in DR/IR shift state it can be up to 7 microseconds (if I remember).

> 
> This software for the parallel port i wrote runs completely in
> user space, though it depends on the /dev/parport devices of
> Linux.  It can:
> - test the parallel port (reading/writing pins with a user interface)
> - read/write several EEPROMs (24Cxx, 93X6, M95XXX) (batched or interactive)
> - read Gamepads (Playstation)
> - debug an ARM7TDMI (read/write registers/memory, download S-Records
>   and start them)
> 
> I'll release that library under a GPL soon, at the moment i'm still
> fighting with my fresh installed Linux system.


Great I think you can do a lot of people a real BIG favour.

> 
> 
> Best regards,
> Torsten.
> 
> avr-gcc-list at http://avr1.org


Regards,


Armand


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Armand ten Doesschate
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5652 XL Eindhoven
tel : (++31) 40 2571 274
the Netherlands
e-mail : address@hidden
avr-gcc-list at http://avr1.org