Re: [avr-chat] 644 again

[Steve Franks]

Nothing on the reset except the jtagice.  I just wired it for a momentary to ground, but it doesn't appear to work on the momentary until you unplug the jtagice, even if you disconnect the reset lead on the jtagice, must be some other pin locking the thing up somehow...

Steve

On 9/1/06, Andy Warner <address@hidden> wrote:

On 9/1/06, Steve Franks <address@hidden> wrote:
> Ok, now I feel like a dufus.  The problem appears to be a function of the
> jtagiceII, the one variable I never changed while pulling out my hair last
> night/this morning.  (At least my pcb's are proven good now) - WIth it
> (jtagice) removed, toggling the reset pin causes normal execution.  So it
> would appear my jtagice interacts radically differently with the Mega644
> than with most of our other designs (which use 162 and 128 mostly).  Note
> [...]

I have a 128-based project (that is mothballed for different, totally
unrelated reasons) that exhibited similar behaviour. It would not
reliably come out of reset after the jtagice was done, I did not try
single stepping through the code from the first instruction, so I have
no idea if that worked.

If I remember correctly (I'm @ a customer site w/o access to the
schematics for that project) it may have had an LCD controller that
also hung off the reset line, in addition to external Power-on-reset
and reset button circuitry... Does your design have any of this extra
stuff hanging off the reset line too ?

Because his board had a reset button, and the project got put into
hibernation soon after the prototype boards came back, I never really
drilled down into this, though I knew I'd need to figure out what was
going on.. If I can find some spare cycles, I'll see if I can't dig it out,
hook up a scope and see what's happening - maybe it'll help triangulate
on your problem..

--
Andy

-- 
Steve Franks, KE7BTE
Staff Engineer
La Palma Devices, LLC
http://www.lapalmadevices.com
(520) 312-0089