AVR-Chat

On Thu, May 19, 2005 at 11:14:16PM -0400, wbounce wrote:

> This all started when I tried to program the problem board with an
> updated program. It did its usually reading ### 100% and device
> signature messages and started on the writing #### part when wheels
> on my robot started turning. It finished writing and reading again
> and then it failed verification.

I wonder if there could have perhaps been a power supply brown-out
during programming which corrupted the fuse bits?

One of the most common fuse bit problems is setting the fuse bits to
use an external clock as opposed to the external crystal or internal
oscillator.  When set to use an external clock, then the chip won't
run and will refuse to be programmed until an external clock is
provided.

Try supplying around a 1 MHz TTL square wave into the XTAL1 input (pin
24).  You can easily access this pin by the right hand pad of the
external crystal.  You can supply this with most any function
generator (just be sure you limit the voltage to 5V), or even a second
AVR board simply programmed to toggle one of its I/O pins.

With the signal applied, retry entering programming mode.  If you get
into programming mode, then you can reset the fuses back to their
defaults and you should run normally after that.  The default fuses on
your MAVRIC-II board are: efuse=0xff, hfuse=0x89, lfuse=0x3f.

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