[sdiy] a provoking question about time

rburnett at richieburnett.co.uk rburnett at richieburnett.co.uk
Fri Jun 24 12:42:05 CEST 2022


I know that some products I designed using dsPIC30F series (not audio 
related) are in use in tens of thousands around the world and I haven't 
heard about any failures.  But of course they might have gradually been 
replaced over the intervening two decades!  I also noticed that the 
longevity of the Flash is longer for these first generation 5V dsPIC 
parts.  My understanding is that re-writing pages of Flash to store user 
parameters also shortens the longevity.  Some other microcontrollers I'm 
using now quote longevity for <1000 E/W cycles and another smaller 
figure for >1000 E/W cycles!  (That's one good reason not to sell 
development prototypes.)

Perhaps it's possible to protect the firmware with an ECC block (error 
correcting code,)  so that the first sign of corruption can be detected 
*and then corrected* with a fresh re-write!  Sounds like a lot of effort 
to go to though (>.<)

-Richie,



On 2022-06-23 10:34, Roman Sowa wrote:
> Hello,
> what are your concerns about flash retention time in microcontrollers?
> Usually PIC18 and PIC16 claim 40 years in datasheet, but dsPIC only
> 20.
> I've seen corrupted memory in products made about 15 years ago with
> dsPIC, so datasheet value seems real.
> 
> One way to do it is to rewrite all memory from time to time, but how
> to do that? Even if there's real time clock running, the user may
> always change the date, and if it's not alowed, the battery or
> supercapacitor may die, or get ripped away. My idea is to clearly
> state somewhere, in manual, or on the device "please run maintenance
> procedure if it's year ending with 0 or 5" but I'm affraid nobody will
> do that anyway, and it seems foolish.
> 
> People have no problem giving their cars every year for expensive
> maintenance, but nearly nobody ever does that with non-industrial
> electronic equipment. That goes sligltly better with musical
> instruments, but anyway many of them go to service only after it's too
> late and it's simply broken.
> 
> I'm not very fond of general trend which is "buy new stuff every 2 
> years".
> 
> Roman
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