CKOUT and fuse repair

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Hey guys, quick question.

can you use CKOUT on say a attiny45 or atmega162, to fix a dead attiny2313, to repair its fuses?

and if so, then do i just connect the CKOUT pin witch ever that is, to xtal1, correct?

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Yes. Xtal1 is the pin to feed-in a clock. Assuming you mean with "dead 2313" a 2313 of which the oscillator-fusebits are set wrong :)

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How to set attiny45 to read external clock?

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Suggest you use this:

 

http://www.engbedded.com/fusecalc/

 

If I pick the "Ext clock" option (and 65ms start up time to be on the safe side)  but leave everything else at default then I come up with:

 

 

HOWEVER do you *really* mean "extternal clock". Do not make this setting if you actually mean "external crystal". An external clock and an external crystal are two very different things. If you actually have a crystal but pick "ext clock" then it will not work and you will find it very difficult to reprogram the AVR!

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Im sory im just newbie and i cant speak english well
Im just want the attiny45 read external crystal
Thanks for your answer

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almeidi wrote:
Im just want the attiny45 read external crystal
Well the next question is: what speed of crystal?

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Speed is 12Mhz

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OK so if you go to the Engbedded site I linked to above and put in "Tiny45" then among the clock options the "safe" one to choose for a 12MHz crystal is highlighted here:

 

 

The frequency is definitely above 8MHz so you want one of the 8.0- MHz (8MHz and upwards) options.

 

You are then faced with deciding how long the AVR waits at start up to give the cyrstal time to start full resonance. The "safe" option is the 16,000 clock and 65ms option. As shown the at is the bottom option in the list.

 

Assuming you are leaving all other options at default. This gives:

 

So those are the fuse values you need to program. As soon as you have set those fuse values the AVR will expect to find a crystal (and two capacitors) across the XTAL1/XTAL2 pins from next power on.

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Thanks for your best answer
I will try it

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I have try it but my micro can't start and read again.
How to program?
I try with GUI USBASP

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Did you put the crystal, and an 18pf capacitor on each XTAL line to ground lie the datasheet reads?

 

Jim

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Yes i put it in PINB.3 and PINB.4
and then i try to set fuse with avrdude
I set hFuse DF, lFuse 7F and eFuse FF
What im missing?

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So the crystal is across pins 2 and 3 but do you have a 10..20pF capacitor going from each pin to ground too ?