Dear IaMaPlAyEr,
In message <2ae8403e0912221835s575a3e31m7578652a6d1e7...@mail.gmail.com> you
wrote:
>
> After I read the datasheet of original chip, I found the parameter
> tRCD is wrong!
> In code, tRCD is set to 10ns, but in datasheet, the minimal tRCD is 15ns.
...
> Could somebody give me some advice to determine which value of tRCD is better?
> thanks.
This depends on what you want to do.
Many people overclock their processors to get a little more
performance for the buck. Doing this, they hazard the consequences
like reduced reliability and lifetime.
It's the same here: you can go for reliability and lifetime and
strictly follow the specifications of the manufacturer, or you can try
a hand-optimized set of settings that appears to be working for you
(but may fail on other boards oin the same type, or at other
temperatures or other operating conditions, etc.).
It's also a matter of warranties - when you have 50,000 systems
failing in the field becuase of memory issues you cannot blame the
chip manufacturer if you are running their chips out of spec, and you
might even sued for punitive damages because of gross negligence by
your own customers.
Go figure...
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
Totally illogical, there was no chance.
-- Spock, "The Galileo Seven", stardate 2822.3
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