[sdiy] a provoking question about time

mskala at northcoastsynthesis.com mskala at northcoastsynthesis.com
Fri Jun 24 16:04:25 CEST 2022


On Fri, 24 Jun 2022, Roman Sowa wrote:
> Noone wants to touch the "fuse" settings.
> But then again, if this is the same kind of flash as rest of memory, and not
> any "high endurance" or whatever, with 10 times bigger transistors, then it's
> really dead end.

That was my thought - you don't want to change the fuse settings at run
time, but they are presumably as vulnerable to bit rot as anything else in
program memory, and the uC won't boot without them, so if you think you
need to refresh proram memory in general then you definitely need to
refresh those bits in particular.

> But do we have to erase it at all? It is to be rweritten with the same value
> so no need for erasing config bytes. I haven't planned to erase anything in
> the program memory either, just write the same content to pump up the charge
> in flash cells.

Rewriting locations without erasing them first is another thing the
Microchip documentation specifically says not to do.  Maybe it'll work.
It's plausible that it should work.  It might even be better for refresh
purposes than erasing first.  But I don't *know* that, and doing it would
seem to invalidate any promises about memory lifetime that the
manufacturer might have originally made.

-- 
Matthew Skala
North Coast Synthesis Ltd.


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