Hi everybody
I have made a system using 89c2051 and it senses a port bit whether it is high three times at intervals of 15 minutes and performs other duties. This checking goes on day in and out.
My question is what is the reasonable life of the chip if this goes on like this without any respite.
I have considered the question of using the idle provision but am unable to use that effectively.
Hope some of you will have an answer for me.
-- Sandy Archer Reply to newsgroups only
I would think several decades at least, probably a lot more. Logically first chips to die would be hot-running semiconductors with tiniest process (65um in modern cpus). A modern cpu would probably be toasted in 20-50 years. I think Jim could say more on that matter.
M
see
I dont know how long the flash will retain it's memory, possibly decades. What will probably fail will be any electrolytics involved with the circuit
martin
You need to consider Ta, and reliability will also probably be affected if you're drawing/sourcing a bunch of current from port pins:
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Like they say.. "No moving parts!"
-mpm
The failure process could be speeded up a bit by using tantalums. SCNR.
But yes, the chip itself will probably live almost forever unless it is flying about in outer space or otherwise exposed to radiation. There is stuff here in the house that contains a uC and has run for more than two decades almost non-stop, only briefly interrupted by moves. If the flash is a concern it could be re-flashed every five years or so.
If it's mission critical Sandy could consider using 3-5 uCs with majority decision and inconsistency alert, similar to how it is done on board of an aircraft. Or at least some kind of code redundancy in flash plus regular CRC.
-- Regards, Joerg http://www.analogconsultants.com/
Many thanks to all of you who were kind to respond to my query and clear my worry.
And the link to the Atmel paper was a great help.
Thanks again
-- Sandy Archer Reply to newsgroups only
Also, I know it wasn't exactly your question, but the 89C2051 has (or is in the process of being?) replaced by the 89S2051. Which in this case is a good thing because it gives you lower voltage options and in- system program capability.
So in that sense, the C2051 is already "dead".
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