Re: [avr-chat] Crystals (was ATmega32 @ 16MHz : fuse bits ??)

[Vincent Trouilliez]

> Before you give up, though, your idea of having other people read back
> to you the fuse settings that work for them is a good one.
> 
> Using AVaRICE, my fuses (with 15.36 MHz crystal) read thus:
> 
> Reading Fuse Bytes:
>   Extended Fuse byte -> 0xff
>       High Fuse byte -> 0x1b
>        Low Fuse byte -> 0xff

Ah, this means CKOPT = 0, SUT=11, and CKSEL3:0 = 1111, which wa sthe
first thing I tried, and which doesn't work. Well, at least I know that
these are the correct settings and that the problem must therefore be
somewhere else.

> Now I have to use AVRdude for the first time ever ... OK, I've got the
> device signature, now how do I read the fuses? ... google ... avrdude
> -c
> STK500 -p m16 -U hfuse:r:high.txt -U lfuse:r:low.txt ... invalid
> output file
> format: -1.  Try WinAVR TkInfo.  Ah, here's an explanation of the
> format ...
> use i for intel hex ... fortunately I can read intel hex files and,
> yes, the
> high byte is 1B and the low byte is FF.

Oh, that was very complicated indeed, in my previous mail I suggested
the use of the "terminal" mode which takes 2 seconds and is very
simple :o)

> re hfuse
> re lfuse

Thanks for going through all this trouble though...

> 
> So, that's what works for me.  If you inject the clock you use to
> recover your chip when the oscillator isn't running, can you read back
> your fuses?

Oh yes, using the "rescue" external clock signal (simply my bench
function generator), the AVR runs my program just fine and I can use
avrdude as normal, to read/write the fuse or anything. 

> What are they set to?

High fuse byte: 0xD1
Low fuse byte:  0xFF

Today I realise that D1 meant CKOPT unprogrammed, oops. Set it to 0
(0xC1), hoping for the best, but no, oscillator still won't start...
I would try with a lower and/or different crystal, but could find one
anywhere in my drawers. Will visit a friend or two to see what they have
lying around...


--
Vince