AVR-Chat

> What happens if you have a soldered an AVR part on a board and 
lock up
> the ISP mode? - bad news.
> I know people who refuse to use SMD or solder DIP AVR parts into 
any
> board, and I must say I'm one of them. Call me paranoid, but I'm 
not
> going to design in a non-robust ISP system into one of my designs.

That is paranoid, and for a company making real products, monetarily 
wasteful.  I've never 'accidentally' disabled ISP on an AVR, and 
I've used plenty of them.  I mean, how can you inadvertently disable 
ISP other than (1) clicking on the configuration bit setting in a 
programming application that you didn't need to or (2) perhaps 
having signal integrity problems during programming?  In the first 
case, that's clearly user error (and something that should be 
learned long before a product ships) and in the second case it's a 
bad design anyway and you're lucky if programming is the only thing 
you have problems with.

There are plenty of commercial products out there that can 
be 'killed' if 'things go wrong' during an upgrade -- the prime 
example being PCs, where a power outage in the middle of re-flashing 
the BIOS ROM can potentially leave it completely dead.

> >You do have to make sure that the programmer isn't running too 
fast
> for the 
> >target system, especially when working with <1 MHz clocks.
> 
> Yet another silly AVR specific thing.

Is the PIC programming interface completely asynchronous?  If not 
surely there's some maximum clock rate on the data, right? 

> I can't believe the guys who designed the AVR ISP did it in this 
way,
> it's completely non-robust. 

I wouldn't argue that there isn't room for improvement, 
but 'completely non-robust' is a patently false characterization. 

---Joel