AVR ATmega88 fuse bit by mistake wrong value how to reset it

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#1
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Hi there,

Is is so that by mistake if i had write fuse bit for External RC oscillator and in board i only have external crystal then i can not re-write fuse bit for atmega88 until i connect it with external rc oscillator? Because i have already facing the problem that if i write this fuse bits as External RC then i am unable to re-write the fuse bit. I have tried this for another IC also. When i write fuse bit, it is not even connecting to my AVR mkII ISP programmer. In other board I have to use internal RC osc, but I have written fuse bit to external Crystal, after that ic could not connect to mkII. Is there any point that I am missing. Is there any way to save my IC?

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The ATmega8 has an 'Ext RC' option.
The ATmega88 does not have an 'Ext RC' option.

You can get the mega8 working by supplying an external RC.
You can get both the mega88 (and any AVR) working by supplying an External clock to XTAL1. It does not matter what your fuses say, the 'External' clock will win.

David.

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Read this - see if anything helps...

How to recover from a "locked out" AVR

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hmm.. does it means that if i give external clock on XTAL1, i can reconnect may ic to mkII?

[yes of'course]. I have saved my two. Thank you.

Last Edited: Tue. Dec 6, 2011 - 12:22 PM
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Quote:

does it means that if i give external clock on XTAL1, i can reconnect may ic to mkII?

What in the article that Cliff linked to are you doubting?

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Johan,

To be fair my post was at 12:04 and his at 12:05. I think he may not have seen mine when he wrote that. Hopefully the article will explain any doubts he has.

Cliff

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Thanks to :
david.prentice,clawson,JohanEkdahl for taking interest in many like me. Yes my confusion is solved. thanks again i was reading article.