Re: [avr-chat] Re: Programmer for everyone!

[Joerg Wunsch]

Clemens Koller <address@hidden> wrote:

> Is reengineering debug interfaces illegal of a product I bought?!

In EU, it's IMHO only legal if you cannot otherwise make use of
certain features of the product.  As avrdude and avarice do support
Atmel's official tools, and as the interface of those tools is
publically subscribed, you'll have a hard time justifying
reengineering it.

(USBisp)

> Then, my idea was to extend i.e. the USBisp with a debugwire
> functionality (if leagal 8-)

Unlike Graham, I don't think that's worth the while.  You'll have to
spend a much larger controller (perhaps even two), and then, you'll
end up with basically an AVR Dragon.  As the AVR Dragon is sold fairly
cheap (compared to the JTAG ICE mkII), even with hobbyist prices, I
doubt you can cut its price.  The Dragon offers full debugWire
debugging for all AVRs that have debugWire.

> on the one hand and with generic
> JTAG support on the other hand (I don't know if it's already
> in the software, shouldn't be a big deal).

Generic JTAG support for programming might be possible as the JTAG
programming is documented.  Only JTAG debugging isn't documented.  I'm
afraid though that you have to at least replace the ATmega8/88 by an
ATmega168 in order to fit the respective code.

But again, the AVR Dragon can already handle all this, and has
established tool support.

The only thing the Dragon doesn't handle is JTAG debugging of CPUs
larger than 32 KiB of ROM.

> (*) Programming of an AVR in a JTAG chain isn't possible, right?!

Supposedly, it is, both with 3rd-party JTAG tools as well as with the
JTAG ICE / AVR Dragon.  Even debugging should be possible, but I'm not
sure about the implications (like everything getting slower).

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)