ATMega8 + fuses thrashed? reset pin disabled?

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#1
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Hi all again.
I know fuses getting "thrashed" is an old topic.

Several times before, I've been able to recover "dead" AVRs by clocking them externally (xtal1 pin) when, somehow, fuses got overwritten with unknown values.

Some days ago, I was programming an atmega8 with a SPI programmer (namely, avrdude and sp12), and suddenly, probably because of some bad connections, avrdude issued an error. After that I couldn't enter programming mode.
I tried external clocking several times too, but nothing happened.
I know my programmer works alright because I tried it later with a "good" atmega8.

What I think happend here is that the fuse that contains the bit "RSTDISBL" got a 0 value. This would make it impossible for an SPI programmer right?

If that's the case, then what can I do? I realised now that I have some other AVRs which might be in the same "state" and I thought were dead.

As I read in the datasheet, a parallel (true parallel) programmer is able to reprogram things back. Is there a schematic and pc program out there to do that?

Thanks in advance to everyone!

Carlos

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Either an STK500 or a Dragon would allow parallel programming of a Mega8 but replacing the chip is obviously the cheapest option.

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I see, thanks for the answer!

does anyone know of a parallel programmer with schematics and code on the net??

Thanks again,

Carlos

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The only one I've ever heard of (apart from STK500 and Dragon) is http://www.der-hammer.info/hvpro...

But given it's complexity I can't help wondering if the $49 Dragon isn't simply the easiest/cheapest solution

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I see.. you're right, the dragon looks better!

well thanks for the info.

The other way would be to use another avr(like mega32) to reprogram the fuses. I'll try that too.

Thanks!