Citlivost pouzdra SDRAM na statickou el. ???

Slavomir Skopalik skopalik na elektlabs.cz
Sobota Září 29 12:25:03 CEST 2012


A neni problem s refresh?

Auto refresh

It is possible to refresh a RAM chip by opening and closing (activating and
precharging) each row in each bank. However, to simplify the memory
controller, SDRAM chips support an "auto refresh" command, which performs
these operations to one row in each bank simultaneously. The SDRAM also
maintains an internal counter, which iterates over all possible rows. The
memory controller must simply issue a sufficient number of auto refresh
commands (one per row, 4096 in the example we have been using) every refresh
interval (tREF = 64 ms is a common value). All banks must be idle (closed,
precharged) when this command is issued.

Slavek

Ing. Slavomir Skopalik
Jednatel spolecnosti
Elekt Labs s.r.o.
Sber a vyhodnoceni dat ze stroju a laboratori 
systemem MASA (http://www.elektlabs.cz/m2demo)
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> -----Original Message-----
> From: hw-list-bounces na list.hw.cz 
> [mailto:hw-list-bounces na list.hw.cz] On Behalf Of Jaroslav Buchta
> Sent: Saturday, September 29, 2012 10:17 AM
> To: HW-news
> Subject: Fwd: Citlivost pouzdra SDRAM na statickou el. ???
> 
> 
> Tak pri hrani s ARMem jsem narazil na dalsi zahadu, kdyz 
> polozim prst na 
> pouzdro SDRAM tak se spolehlive poskodi obsah, program se zabehne - 
> myslim na pouzdro, bez dotyku vodivych casti. Pokud se druhou rukou 
> drzim zeme, tak je to podstatne min pravdepodobne a pokud 
> saham na ruzne 
> vodive cesty - data, adresy i SCLK tak to vubec nevadi. Muze 
> to byt tim, 
> ze se prenese naboj do kondenzatoru na cipu nebo je nekde 
> nejaka chyba? 
> Jinak program beze pul dne bez nehody, na frekvenci hodin 
> nejak zda se 
> nezalezi. Deska je 4-vrstva a napajeni SDRAM je bohate blokovano
> 
> 
> 
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