AVR-Chat

Oh yeah Should I put a current limiting resistor in series on the 
wire?


--- In AVR-Chat@yahoogroups.com, Brian Dean <bsd@b...> wrote:
> 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/