Re: [avr-gcc-list] Homebrew ICE?

[Joerg Wunsch]

As Erik Christiansen <address@hidden> wrote:

>   If your schematics import into Eagle, I'd be tempted to help with
>   implementing the intended improvements, and have a couple of boards
>   made.

I'm afraid it won't import very nicely into Eagle, i'm using BAE here
(http://www.bartels.de/).  The schematics is currently using three
schematics sheets already, so it would be fairly cramped if you try to
press it into the single sheet allowed by the free-of-charge version
of Eagle.

>   Does it need some additional software between it and gdb?

Sure, just as with the Atmel-supplied JTAG ICE, it needs avarice as
the glue.  Ted Roth once thought about the idea to teach GDB the JTAG
ICE protocol, but i haven't heard anything about this idea lately.

>> I'm not sure about the legal situation though: as long as we have to
>> rely on Atmel's firmware, it's sort of a grey zone.

>   Would that depend on the circumstances under which the Atmel firmware
>   has been obtained? 

The Atmel firmware is obtained as part of AVR Studio.  The only
restriction for it i can remember is that you are only allowed to give
the entire AVR Studio software package away -- but in this case, you
aren't giving it away but using it yourself.  But a lawyer would
perhaps have to read the fine print...

>   I don't suppose a couple of really fast optocouplers would provide
>   the required data rate, while solving both the level and isolation
>   issues? (I should check up on developments on that front.)

I'm afraid they risk to draw too much current from the target.

Larry Barello suggested the use of MAX3378 level shifters which sounds
fairly tempting to me (e. g. they'd cover the entire allowable target
Vcc range).  OTOH, they are certainly a lot more expensive than the
74HC stuff i'm using currently, and people wanting to build their own
might be faced with problems getting these chips.  Maybe i'll design
the PCB to allow an alternate version between 74HC and MAX337x.
-- 
J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/