hi mark:
the last week i've been writing a lot of "user flash code", anthough i have not actually let the smoke out of a chip by errant clock frequencies, the documentation clearly states that operating above 200khz will "stress the flash". there is a second criteria that includes the bus clock as well, yielding sort of a convoluted calculation requirement. for some reason, i think that i also read that the internal flash voltage is dependent on the oscillator frequency but i can't find the text right now (could have been an errant firing synapse as well). if that chip is drawing close to a half an amp ... let's have a moment of silence now .. it has passed onto chip heaven.
don't ya hate soldering those qpfs?
regards,
ed
Hi
I soldered in a new device and it works again. I will be more careful in future, including building in a software check before zapping (check that frequency has been programmed correctly).
By the way, soldering in the QFP is not such a big task. Here's how it seems to work best:
1. Place the chip as accurately as possible and solder two corners to fix it
2. Solder all pins making big fat short circuits over every two or three pins, just make sure there's a good contact and lots of solder.
3. Use desoldering braid to suck off as much of the solder as possible (I use SPIRIG 3S-WICK).
4. Check the contacts under a mag. glass to ensure that there are no short circuits under the chip some where (if there are repeat 2..3 for the pins).
After cleaning the flux away, the result looks almost as good as reflow soldering - takes 5 minutes and is surprisingly reliable.
Cheers
Mark Butcher
www.mjbc.ch