AVR-Chat

While skimming and deleting this thread, I have just been debugging a 
returned
board that does seem to have a fuse/lockup problem.  I cannot reach the 
Tiny26
through the ISP (STK500 cable); but the Tiny continues to operate it's 
pre-downloaded
program.  I assume that the serial enable fuse was accidently turned off 
by someone,
and now there is nothing that can be done to load new code.
The Tiny is an smt, soldered in place, and even if I could get it off 
cleanly, I don't
think there's any way to place it on the STK500.
Should I assume there's no way to move forward?

thanks,
Ken



Graham Davies wrote:

>--- In AVR-Chat@yahoogroups.com, "David Jones" <david.jones@s...> 
>wrote:
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What happens if you have a soldered an AVR part on a board and lock up
>the ISP mode? - bad news.

>>... ISP modes on other micros
>>like the PIC just work. No traps.
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>Maybe the PIC, but not all micros. The ZiLOG Z8 Encore! has a far 
>worse gotcha than the AVR because the oscillator settings are 
>controlled by the first word of program memory, not by separately 
>accessed fuses. So, you can shoot yourself in the foot much more 
>easily, including just looking at program memory in the debugger and 
>trying to change what is stored by typing over values. It works, but 
>thereafter nothing else does.
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>I agree that this is an issue for beginners and more attention should 
>be brought to it.
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>Recall that I discovered that fuse gotchas are solved for AVRs with 
>the JTAG interface because this interface does not require the clock 
>to be running so you can repair any fuse misconfigurations.
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>The thread on the STK500 was really interesting. I was, of course, 
>looking for new product opportunities, but it seems that ISP is a 
>generally a solved problem.
>
>Graham.
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>Yahoo! Groups Links
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