Avrdude problems...

[StuartL]

http://robosavvy.com/forum/viewtopic.php?p=17416&highlight=rom

Before dumping in ,I first tried to tune some of my Atmega8 to 16Mhz,I ended up messing with the fuse bits and both the Atmega8 stopped responding.Could you please tell me the exact fuse settings (lfuse and fuse) for the Atmega8

Have you ever wondered where the line is when you say "Do you know what, I should stop messing with things I don't understand?"

I think you crossed this line a few weeks ago.

By reading the ATmega8 PDF we got the fuse bits right first time. I don't doubt that anyone can make mistakes, even a few in a row (just look at some of my posts for evidence), but it's becoming apparent that you're disassembling, tinkering and breaking things you don't fully understand. My patience in helping you out in the forums and via PM is severely limited when you're demonstrating a severe unwillingness to read read read like the rest of us have done to get it right.

The documentation is there. The fuse bits are there. If you don't understand the brown out detector, the difference between a low power oscillator and a full swing oscillator then it's time to read more PDFs, google a bit and maybe even build a test circuit on some veroboard to check your fuse bit settings and firmware before you break more AX12s.

I'm sure myself, and most other people here, would be much more willing (and able!) to help if instead of breaking something you said:

I've found this link on the net which has these fuse bits for an AX12 with a 16MHz oscillator and they look right but they've got these bits for the brown out detector and it doesn't look right for a 5v part. When I tested these bits on my development board this happened and then I found this link which showed that bit number 1 was wrong. I don't understand why, can anyone help?

To recover your AX12s you'll need to either write or recover the bootloader, program the bootloader and application, set the fuse bits to boot from bootloader with a 16MHz external crystal and you probably want the brown out detector enabled. And all of this from the SPI pins.

If you've installed the fuse bits so wrong that the SPI programming pins no longer work you're screwed unless you want to strip the chip off the board and build a parallel programmer. I know this because we had to do it.

[bootstrap]

Have you ever wondered where the line is when you say "Do you know what, I should stop messing with things I don't understand?"

I completely agree with you,it is my mistake.I am sincerely sorry about it