AVR-Chat

On Fri, Nov 05, 2004 at 02:43:54PM +1100, David Jones wrote:

> That's beside the point. It can and does happen.  What happens if
> you have a soldered an AVR part on a board and lock up the ISP mode?
> - bad news.

Are you sure it is the SPIEN fuse?  According to the datasheet you
cannot change the SPI enable fuse when actually using the ISP
interface.  I've tried to purposefully disable it using ISP
programming mode to no avail - it remains enabled.  I think one must
use JTAG or high voltage parallel programming to disable the SPIEN
fuse.

However, sometimes folks are guilty if changing the on-chip clock
source options which can leave the chip without a working clock.  For
example, can can set the fuse bits to select an external clock source
when there is none.  Not as deadly as clearing the SPIEN fuse as you
can generally feed in the needed clock and get back up and running.

It does sort've beg the question though - whey even have the option of
disabling the SPI programming interface?

-Brian
-- 
Brian Dean
BDMICRO - ATmega128 Based MAVRIC Controllers
http://www.bdmicro.com/