Re: [avr-chat] Dragon: mega slow at dumping Flash, normal ?

[Joerg Wunsch]

"Heike C. Zimmerer" <address@hidden> wrote:

>> I did not expect to see any interaction of the SPI and debugWIRE
>> myself?

> So did I.  That is, until I stumbled across that behaviour ... Never
> found any mention of it in the ATmega168's data sheet (that's where
> I encountered it).

It's mentioned in the description of the PRSPI bit.

In theory, if you can connect debugWIRE to the target while the
power-on reset is still active, it might be possible to take over
control of the target MCU before it is able to reprogram the PRR.  In
that case, it would be possible to overwrite the respective flash page
with something else.

In practice though, I'm afraid the only way out of that situation is
high-voltage programming.

On-chip debugging and power reduction is almost always not a very
useful combination, not even with JTAG: the OCD feature causes the
main oscillator to never stop, so there's no real power-down sleep
possible.

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

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