Re: [avrdude-dev] Fusebit (RSTDISBL) on ATtiny15

[Brian Dean]

On Thu, Dec 11, 2003 at 11:15:28AM +0100, address@hidden wrote:

> If I want to use PB5 as a "normal" I/O instead of RESET on a
> ATtiny15 I have to program the RSTDISBL-fuse. But after that I can't
> use the ISP (low-voltage) programming mode, right? Currently I'm
> using Brian Dean's programmer. So, isn't it possible to use this
> thing furhter on?

Once you set the fuse bit so that the /RESET becomes an I/O pin, you
can no longer access programming mode via the ISP.  If you have an
STK500, or other programmer that supports parallel programming mode,
you should still be able to program it that way, but the chip usually
needs to be removed from the circuit for parallel programming.

> BTW: with what command can I program the fuse?

In AVRDUDE, the easiest way to set fuse bits is to program them on the
command line using the -U option:

        avrdude -p <part> -U fuse:w:<value>:m

Where <value> is the desired byte value of the specified fuse byte.
There's currently no way to set an individual bit - you need to figure
out what the fuse byte needs to be and set all the bits at once.  You
can preced the <value> field with '0x' to use hex values which is
generally easier to use to do bit arithmetic in your head than
decimal.

For displaying current fuse values, terminal mode is nice:

        avrdude -p <part> -t
        ...
        avrdude> d fuse

You can also set fuse values from here using the 'w' command (write).

Cheers,
-Brian